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/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* This file is available under and governed by the GNU General Public
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* License version 2 only, as published by the Free Software Foundation.
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* However, the following notice accompanied the original version of this
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* file:
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*
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* Written by Doug Lea with assistance from members of JCP JSR-166
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* Expert Group and released to the public domain, as explained at
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* http://creativecommons.org/publicdomain/zero/1.0/
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*/
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package java.util.concurrent;
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import java.util.concurrent.locks.*;
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import java.util.concurrent.atomic.*;
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import java.util.*;
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/**
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* An {@link ExecutorService} that executes each submitted task using
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* one of possibly several pooled threads, normally configured
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* using {@link Executors} factory methods.
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*
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* <p>Thread pools address two different problems: they usually
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* provide improved performance when executing large numbers of
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* asynchronous tasks, due to reduced per-task invocation overhead,
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* and they provide a means of bounding and managing the resources,
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* including threads, consumed when executing a collection of tasks.
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* Each {@code ThreadPoolExecutor} also maintains some basic
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* statistics, such as the number of completed tasks.
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*
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* <p>To be useful across a wide range of contexts, this class
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* provides many adjustable parameters and extensibility
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* hooks. However, programmers are urged to use the more convenient
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* {@link Executors} factory methods {@link
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* Executors#newCachedThreadPool} (unbounded thread pool, with
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* automatic thread reclamation), {@link Executors#newFixedThreadPool}
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* (fixed size thread pool) and {@link
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* Executors#newSingleThreadExecutor} (single background thread), that
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* preconfigure settings for the most common usage
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* scenarios. Otherwise, use the following guide when manually
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* configuring and tuning this class:
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*
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* <dl>
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*
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* <dt>Core and maximum pool sizes</dt>
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*
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* <dd>A {@code ThreadPoolExecutor} will automatically adjust the
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* pool size (see {@link #getPoolSize})
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* according to the bounds set by
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* corePoolSize (see {@link #getCorePoolSize}) and
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* maximumPoolSize (see {@link #getMaximumPoolSize}).
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*
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* When a new task is submitted in method {@link #execute}, and fewer
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* than corePoolSize threads are running, a new thread is created to
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* handle the request, even if other worker threads are idle. If
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* there are more than corePoolSize but less than maximumPoolSize
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* threads running, a new thread will be created only if the queue is
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* full. By setting corePoolSize and maximumPoolSize the same, you
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* create a fixed-size thread pool. By setting maximumPoolSize to an
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* essentially unbounded value such as {@code Integer.MAX_VALUE}, you
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* allow the pool to accommodate an arbitrary number of concurrent
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* tasks. Most typically, core and maximum pool sizes are set only
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* upon construction, but they may also be changed dynamically using
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* {@link #setCorePoolSize} and {@link #setMaximumPoolSize}. </dd>
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*
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* <dt>On-demand construction</dt>
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*
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* <dd> By default, even core threads are initially created and
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* started only when new tasks arrive, but this can be overridden
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* dynamically using method {@link #prestartCoreThread} or {@link
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* #prestartAllCoreThreads}. You probably want to prestart threads if
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* you construct the pool with a non-empty queue. </dd>
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*
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* <dt>Creating new threads</dt>
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*
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* <dd>New threads are created using a {@link ThreadFactory}. If not
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* otherwise specified, a {@link Executors#defaultThreadFactory} is
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* used, that creates threads to all be in the same {@link
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* ThreadGroup} and with the same {@code NORM_PRIORITY} priority and
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* non-daemon status. By supplying a different ThreadFactory, you can
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* alter the thread's name, thread group, priority, daemon status,
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* etc. If a {@code ThreadFactory} fails to create a thread when asked
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* by returning null from {@code newThread}, the executor will
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* continue, but might not be able to execute any tasks. Threads
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* should possess the "modifyThread" {@code RuntimePermission}. If
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* worker threads or other threads using the pool do not possess this
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* permission, service may be degraded: configuration changes may not
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* take effect in a timely manner, and a shutdown pool may remain in a
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* state in which termination is possible but not completed.</dd>
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*
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* <dt>Keep-alive times</dt>
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*
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* <dd>If the pool currently has more than corePoolSize threads,
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* excess threads will be terminated if they have been idle for more
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* than the keepAliveTime (see {@link #getKeepAliveTime}). This
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* provides a means of reducing resource consumption when the pool is
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* not being actively used. If the pool becomes more active later, new
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* threads will be constructed. This parameter can also be changed
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* dynamically using method {@link #setKeepAliveTime}. Using a value
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* of {@code Long.MAX_VALUE} {@link TimeUnit#NANOSECONDS} effectively
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* disables idle threads from ever terminating prior to shut down. By
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* default, the keep-alive policy applies only when there are more
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* than corePoolSizeThreads. But method {@link
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* #allowCoreThreadTimeOut(boolean)} can be used to apply this
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* time-out policy to core threads as well, so long as the
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* keepAliveTime value is non-zero. </dd>
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*
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* <dt>Queuing</dt>
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*
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* <dd>Any {@link BlockingQueue} may be used to transfer and hold
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* submitted tasks. The use of this queue interacts with pool sizing:
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*
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* <ul>
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*
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* <li> If fewer than corePoolSize threads are running, the Executor
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* always prefers adding a new thread
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* rather than queuing.</li>
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*
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* <li> If corePoolSize or more threads are running, the Executor
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* always prefers queuing a request rather than adding a new
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* thread.</li>
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*
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* <li> If a request cannot be queued, a new thread is created unless
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* this would exceed maximumPoolSize, in which case, the task will be
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* rejected.</li>
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*
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* </ul>
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*
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* There are three general strategies for queuing:
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* <ol>
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*
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* <li> <em> Direct handoffs.</em> A good default choice for a work
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* queue is a {@link SynchronousQueue} that hands off tasks to threads
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* without otherwise holding them. Here, an attempt to queue a task
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* will fail if no threads are immediately available to run it, so a
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* new thread will be constructed. This policy avoids lockups when
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* handling sets of requests that might have internal dependencies.
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* Direct handoffs generally require unbounded maximumPoolSizes to
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* avoid rejection of new submitted tasks. This in turn admits the
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* possibility of unbounded thread growth when commands continue to
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* arrive on average faster than they can be processed. </li>
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*
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* <li><em> Unbounded queues.</em> Using an unbounded queue (for
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* example a {@link LinkedBlockingQueue} without a predefined
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* capacity) will cause new tasks to wait in the queue when all
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* corePoolSize threads are busy. Thus, no more than corePoolSize
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* threads will ever be created. (And the value of the maximumPoolSize
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* therefore doesn't have any effect.) This may be appropriate when
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* each task is completely independent of others, so tasks cannot
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* affect each others execution; for example, in a web page server.
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* While this style of queuing can be useful in smoothing out
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* transient bursts of requests, it admits the possibility of
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* unbounded work queue growth when commands continue to arrive on
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* average faster than they can be processed. </li>
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*
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* <li><em>Bounded queues.</em> A bounded queue (for example, an
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* {@link ArrayBlockingQueue}) helps prevent resource exhaustion when
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* used with finite maximumPoolSizes, but can be more difficult to
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* tune and control. Queue sizes and maximum pool sizes may be traded
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* off for each other: Using large queues and small pools minimizes
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* CPU usage, OS resources, and context-switching overhead, but can
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* lead to artificially low throughput. If tasks frequently block (for
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* example if they are I/O bound), a system may be able to schedule
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* time for more threads than you otherwise allow. Use of small queues
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* generally requires larger pool sizes, which keeps CPUs busier but
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* may encounter unacceptable scheduling overhead, which also
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* decreases throughput. </li>
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*
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* </ol>
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*
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* </dd>
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*
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* <dt>Rejected tasks</dt>
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*
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* <dd> New tasks submitted in method {@link #execute} will be
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* <em>rejected</em> when the Executor has been shut down, and also
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* when the Executor uses finite bounds for both maximum threads and
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* work queue capacity, and is saturated. In either case, the {@code
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* execute} method invokes the {@link
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* RejectedExecutionHandler#rejectedExecution} method of its {@link
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* RejectedExecutionHandler}. Four predefined handler policies are
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* provided:
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*
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* <ol>
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*
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* <li> In the default {@link ThreadPoolExecutor.AbortPolicy}, the
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* handler throws a runtime {@link RejectedExecutionException} upon
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* rejection. </li>
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*
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* <li> In {@link ThreadPoolExecutor.CallerRunsPolicy}, the thread
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* that invokes {@code execute} itself runs the task. This provides a
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* simple feedback control mechanism that will slow down the rate that
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* new tasks are submitted. </li>
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*
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* <li> In {@link ThreadPoolExecutor.DiscardPolicy}, a task that
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* cannot be executed is simply dropped. </li>
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*
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* <li>In {@link ThreadPoolExecutor.DiscardOldestPolicy}, if the
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* executor is not shut down, the task at the head of the work queue
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* is dropped, and then execution is retried (which can fail again,
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* causing this to be repeated.) </li>
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*
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* </ol>
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*
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* It is possible to define and use other kinds of {@link
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* RejectedExecutionHandler} classes. Doing so requires some care
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* especially when policies are designed to work only under particular
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* capacity or queuing policies. </dd>
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*
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* <dt>Hook methods</dt>
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*
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* <dd>This class provides {@code protected} overridable {@link
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* #beforeExecute} and {@link #afterExecute} methods that are called
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* before and after execution of each task. These can be used to
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* manipulate the execution environment; for example, reinitializing
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* ThreadLocals, gathering statistics, or adding log
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* entries. Additionally, method {@link #terminated} can be overridden
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* to perform any special processing that needs to be done once the
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* Executor has fully terminated.
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*
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* <p>If hook or callback methods throw exceptions, internal worker
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* threads may in turn fail and abruptly terminate.</dd>
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*
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* <dt>Queue maintenance</dt>
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*
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* <dd> Method {@link #getQueue} allows access to the work queue for
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* purposes of monitoring and debugging. Use of this method for any
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* other purpose is strongly discouraged. Two supplied methods,
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* {@link #remove} and {@link #purge} are available to assist in
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* storage reclamation when large numbers of queued tasks become
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* cancelled.</dd>
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*
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* <dt>Finalization</dt>
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*
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* <dd> A pool that is no longer referenced in a program <em>AND</em>
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* has no remaining threads will be {@code shutdown} automatically. If
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* you would like to ensure that unreferenced pools are reclaimed even
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* if users forget to call {@link #shutdown}, then you must arrange
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* that unused threads eventually die, by setting appropriate
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* keep-alive times, using a lower bound of zero core threads and/or
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* setting {@link #allowCoreThreadTimeOut(boolean)}. </dd>
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*
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* </dl>
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*
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* <p> <b>Extension example</b>. Most extensions of this class
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* override one or more of the protected hook methods. For example,
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* here is a subclass that adds a simple pause/resume feature:
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*
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* <pre> {@code
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* class PausableThreadPoolExecutor extends ThreadPoolExecutor {
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* private boolean isPaused;
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* private ReentrantLock pauseLock = new ReentrantLock();
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* private Condition unpaused = pauseLock.newCondition();
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*
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|
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* public PausableThreadPoolExecutor(...) { super(...); }
|
jaroslav@1890
|
279 |
*
|
jaroslav@1890
|
280 |
* protected void beforeExecute(Thread t, Runnable r) {
|
jaroslav@1890
|
281 |
* super.beforeExecute(t, r);
|
jaroslav@1890
|
282 |
* pauseLock.lock();
|
jaroslav@1890
|
283 |
* try {
|
jaroslav@1890
|
284 |
* while (isPaused) unpaused.await();
|
jaroslav@1890
|
285 |
* } catch (InterruptedException ie) {
|
jaroslav@1890
|
286 |
* t.interrupt();
|
jaroslav@1890
|
287 |
* } finally {
|
jaroslav@1890
|
288 |
* pauseLock.unlock();
|
jaroslav@1890
|
289 |
* }
|
jaroslav@1890
|
290 |
* }
|
jaroslav@1890
|
291 |
*
|
jaroslav@1890
|
292 |
* public void pause() {
|
jaroslav@1890
|
293 |
* pauseLock.lock();
|
jaroslav@1890
|
294 |
* try {
|
jaroslav@1890
|
295 |
* isPaused = true;
|
jaroslav@1890
|
296 |
* } finally {
|
jaroslav@1890
|
297 |
* pauseLock.unlock();
|
jaroslav@1890
|
298 |
* }
|
jaroslav@1890
|
299 |
* }
|
jaroslav@1890
|
300 |
*
|
jaroslav@1890
|
301 |
* public void resume() {
|
jaroslav@1890
|
302 |
* pauseLock.lock();
|
jaroslav@1890
|
303 |
* try {
|
jaroslav@1890
|
304 |
* isPaused = false;
|
jaroslav@1890
|
305 |
* unpaused.signalAll();
|
jaroslav@1890
|
306 |
* } finally {
|
jaroslav@1890
|
307 |
* pauseLock.unlock();
|
jaroslav@1890
|
308 |
* }
|
jaroslav@1890
|
309 |
* }
|
jaroslav@1890
|
310 |
* }}</pre>
|
jaroslav@1890
|
311 |
*
|
jaroslav@1890
|
312 |
* @since 1.5
|
jaroslav@1890
|
313 |
* @author Doug Lea
|
jaroslav@1890
|
314 |
*/
|
jaroslav@1890
|
315 |
public class ThreadPoolExecutor extends AbstractExecutorService {
|
jaroslav@1890
|
316 |
/**
|
jaroslav@1890
|
317 |
* The main pool control state, ctl, is an atomic integer packing
|
jaroslav@1890
|
318 |
* two conceptual fields
|
jaroslav@1890
|
319 |
* workerCount, indicating the effective number of threads
|
jaroslav@1890
|
320 |
* runState, indicating whether running, shutting down etc
|
jaroslav@1890
|
321 |
*
|
jaroslav@1890
|
322 |
* In order to pack them into one int, we limit workerCount to
|
jaroslav@1890
|
323 |
* (2^29)-1 (about 500 million) threads rather than (2^31)-1 (2
|
jaroslav@1890
|
324 |
* billion) otherwise representable. If this is ever an issue in
|
jaroslav@1890
|
325 |
* the future, the variable can be changed to be an AtomicLong,
|
jaroslav@1890
|
326 |
* and the shift/mask constants below adjusted. But until the need
|
jaroslav@1890
|
327 |
* arises, this code is a bit faster and simpler using an int.
|
jaroslav@1890
|
328 |
*
|
jaroslav@1890
|
329 |
* The workerCount is the number of workers that have been
|
jaroslav@1890
|
330 |
* permitted to start and not permitted to stop. The value may be
|
jaroslav@1890
|
331 |
* transiently different from the actual number of live threads,
|
jaroslav@1890
|
332 |
* for example when a ThreadFactory fails to create a thread when
|
jaroslav@1890
|
333 |
* asked, and when exiting threads are still performing
|
jaroslav@1890
|
334 |
* bookkeeping before terminating. The user-visible pool size is
|
jaroslav@1890
|
335 |
* reported as the current size of the workers set.
|
jaroslav@1890
|
336 |
*
|
jaroslav@1890
|
337 |
* The runState provides the main lifecyle control, taking on values:
|
jaroslav@1890
|
338 |
*
|
jaroslav@1890
|
339 |
* RUNNING: Accept new tasks and process queued tasks
|
jaroslav@1890
|
340 |
* SHUTDOWN: Don't accept new tasks, but process queued tasks
|
jaroslav@1890
|
341 |
* STOP: Don't accept new tasks, don't process queued tasks,
|
jaroslav@1890
|
342 |
* and interrupt in-progress tasks
|
jaroslav@1890
|
343 |
* TIDYING: All tasks have terminated, workerCount is zero,
|
jaroslav@1890
|
344 |
* the thread transitioning to state TIDYING
|
jaroslav@1890
|
345 |
* will run the terminated() hook method
|
jaroslav@1890
|
346 |
* TERMINATED: terminated() has completed
|
jaroslav@1890
|
347 |
*
|
jaroslav@1890
|
348 |
* The numerical order among these values matters, to allow
|
jaroslav@1890
|
349 |
* ordered comparisons. The runState monotonically increases over
|
jaroslav@1890
|
350 |
* time, but need not hit each state. The transitions are:
|
jaroslav@1890
|
351 |
*
|
jaroslav@1890
|
352 |
* RUNNING -> SHUTDOWN
|
jaroslav@1890
|
353 |
* On invocation of shutdown(), perhaps implicitly in finalize()
|
jaroslav@1890
|
354 |
* (RUNNING or SHUTDOWN) -> STOP
|
jaroslav@1890
|
355 |
* On invocation of shutdownNow()
|
jaroslav@1890
|
356 |
* SHUTDOWN -> TIDYING
|
jaroslav@1890
|
357 |
* When both queue and pool are empty
|
jaroslav@1890
|
358 |
* STOP -> TIDYING
|
jaroslav@1890
|
359 |
* When pool is empty
|
jaroslav@1890
|
360 |
* TIDYING -> TERMINATED
|
jaroslav@1890
|
361 |
* When the terminated() hook method has completed
|
jaroslav@1890
|
362 |
*
|
jaroslav@1890
|
363 |
* Threads waiting in awaitTermination() will return when the
|
jaroslav@1890
|
364 |
* state reaches TERMINATED.
|
jaroslav@1890
|
365 |
*
|
jaroslav@1890
|
366 |
* Detecting the transition from SHUTDOWN to TIDYING is less
|
jaroslav@1890
|
367 |
* straightforward than you'd like because the queue may become
|
jaroslav@1890
|
368 |
* empty after non-empty and vice versa during SHUTDOWN state, but
|
jaroslav@1890
|
369 |
* we can only terminate if, after seeing that it is empty, we see
|
jaroslav@1890
|
370 |
* that workerCount is 0 (which sometimes entails a recheck -- see
|
jaroslav@1890
|
371 |
* below).
|
jaroslav@1890
|
372 |
*/
|
jaroslav@1890
|
373 |
private final AtomicInteger ctl = new AtomicInteger(ctlOf(RUNNING, 0));
|
jaroslav@1890
|
374 |
private static final int COUNT_BITS = Integer.SIZE - 3;
|
jaroslav@1890
|
375 |
private static final int CAPACITY = (1 << COUNT_BITS) - 1;
|
jaroslav@1890
|
376 |
|
jaroslav@1890
|
377 |
// runState is stored in the high-order bits
|
jaroslav@1890
|
378 |
private static final int RUNNING = -1 << COUNT_BITS;
|
jaroslav@1890
|
379 |
private static final int SHUTDOWN = 0 << COUNT_BITS;
|
jaroslav@1890
|
380 |
private static final int STOP = 1 << COUNT_BITS;
|
jaroslav@1890
|
381 |
private static final int TIDYING = 2 << COUNT_BITS;
|
jaroslav@1890
|
382 |
private static final int TERMINATED = 3 << COUNT_BITS;
|
jaroslav@1890
|
383 |
|
jaroslav@1890
|
384 |
// Packing and unpacking ctl
|
jaroslav@1890
|
385 |
private static int runStateOf(int c) { return c & ~CAPACITY; }
|
jaroslav@1890
|
386 |
private static int workerCountOf(int c) { return c & CAPACITY; }
|
jaroslav@1890
|
387 |
private static int ctlOf(int rs, int wc) { return rs | wc; }
|
jaroslav@1890
|
388 |
|
jaroslav@1890
|
389 |
/*
|
jaroslav@1890
|
390 |
* Bit field accessors that don't require unpacking ctl.
|
jaroslav@1890
|
391 |
* These depend on the bit layout and on workerCount being never negative.
|
jaroslav@1890
|
392 |
*/
|
jaroslav@1890
|
393 |
|
jaroslav@1890
|
394 |
private static boolean runStateLessThan(int c, int s) {
|
jaroslav@1890
|
395 |
return c < s;
|
jaroslav@1890
|
396 |
}
|
jaroslav@1890
|
397 |
|
jaroslav@1890
|
398 |
private static boolean runStateAtLeast(int c, int s) {
|
jaroslav@1890
|
399 |
return c >= s;
|
jaroslav@1890
|
400 |
}
|
jaroslav@1890
|
401 |
|
jaroslav@1890
|
402 |
private static boolean isRunning(int c) {
|
jaroslav@1890
|
403 |
return c < SHUTDOWN;
|
jaroslav@1890
|
404 |
}
|
jaroslav@1890
|
405 |
|
jaroslav@1890
|
406 |
/**
|
jaroslav@1890
|
407 |
* Attempt to CAS-increment the workerCount field of ctl.
|
jaroslav@1890
|
408 |
*/
|
jaroslav@1890
|
409 |
private boolean compareAndIncrementWorkerCount(int expect) {
|
jaroslav@1890
|
410 |
return ctl.compareAndSet(expect, expect + 1);
|
jaroslav@1890
|
411 |
}
|
jaroslav@1890
|
412 |
|
jaroslav@1890
|
413 |
/**
|
jaroslav@1890
|
414 |
* Attempt to CAS-decrement the workerCount field of ctl.
|
jaroslav@1890
|
415 |
*/
|
jaroslav@1890
|
416 |
private boolean compareAndDecrementWorkerCount(int expect) {
|
jaroslav@1890
|
417 |
return ctl.compareAndSet(expect, expect - 1);
|
jaroslav@1890
|
418 |
}
|
jaroslav@1890
|
419 |
|
jaroslav@1890
|
420 |
/**
|
jaroslav@1890
|
421 |
* Decrements the workerCount field of ctl. This is called only on
|
jaroslav@1890
|
422 |
* abrupt termination of a thread (see processWorkerExit). Other
|
jaroslav@1890
|
423 |
* decrements are performed within getTask.
|
jaroslav@1890
|
424 |
*/
|
jaroslav@1890
|
425 |
private void decrementWorkerCount() {
|
jaroslav@1890
|
426 |
do {} while (! compareAndDecrementWorkerCount(ctl.get()));
|
jaroslav@1890
|
427 |
}
|
jaroslav@1890
|
428 |
|
jaroslav@1890
|
429 |
/**
|
jaroslav@1890
|
430 |
* The queue used for holding tasks and handing off to worker
|
jaroslav@1890
|
431 |
* threads. We do not require that workQueue.poll() returning
|
jaroslav@1890
|
432 |
* null necessarily means that workQueue.isEmpty(), so rely
|
jaroslav@1890
|
433 |
* solely on isEmpty to see if the queue is empty (which we must
|
jaroslav@1890
|
434 |
* do for example when deciding whether to transition from
|
jaroslav@1890
|
435 |
* SHUTDOWN to TIDYING). This accommodates special-purpose
|
jaroslav@1890
|
436 |
* queues such as DelayQueues for which poll() is allowed to
|
jaroslav@1890
|
437 |
* return null even if it may later return non-null when delays
|
jaroslav@1890
|
438 |
* expire.
|
jaroslav@1890
|
439 |
*/
|
jaroslav@1890
|
440 |
private final BlockingQueue<Runnable> workQueue;
|
jaroslav@1890
|
441 |
|
jaroslav@1890
|
442 |
/**
|
jaroslav@1890
|
443 |
* Lock held on access to workers set and related bookkeeping.
|
jaroslav@1890
|
444 |
* While we could use a concurrent set of some sort, it turns out
|
jaroslav@1890
|
445 |
* to be generally preferable to use a lock. Among the reasons is
|
jaroslav@1890
|
446 |
* that this serializes interruptIdleWorkers, which avoids
|
jaroslav@1890
|
447 |
* unnecessary interrupt storms, especially during shutdown.
|
jaroslav@1890
|
448 |
* Otherwise exiting threads would concurrently interrupt those
|
jaroslav@1890
|
449 |
* that have not yet interrupted. It also simplifies some of the
|
jaroslav@1890
|
450 |
* associated statistics bookkeeping of largestPoolSize etc. We
|
jaroslav@1890
|
451 |
* also hold mainLock on shutdown and shutdownNow, for the sake of
|
jaroslav@1890
|
452 |
* ensuring workers set is stable while separately checking
|
jaroslav@1890
|
453 |
* permission to interrupt and actually interrupting.
|
jaroslav@1890
|
454 |
*/
|
jaroslav@1890
|
455 |
private final ReentrantLock mainLock = new ReentrantLock();
|
jaroslav@1890
|
456 |
|
jaroslav@1890
|
457 |
/**
|
jaroslav@1890
|
458 |
* Set containing all worker threads in pool. Accessed only when
|
jaroslav@1890
|
459 |
* holding mainLock.
|
jaroslav@1890
|
460 |
*/
|
jaroslav@1890
|
461 |
private final HashSet<Worker> workers = new HashSet<Worker>();
|
jaroslav@1890
|
462 |
|
jaroslav@1890
|
463 |
/**
|
jaroslav@1890
|
464 |
* Wait condition to support awaitTermination
|
jaroslav@1890
|
465 |
*/
|
jaroslav@1890
|
466 |
private final Condition termination = mainLock.newCondition();
|
jaroslav@1890
|
467 |
|
jaroslav@1890
|
468 |
/**
|
jaroslav@1890
|
469 |
* Tracks largest attained pool size. Accessed only under
|
jaroslav@1890
|
470 |
* mainLock.
|
jaroslav@1890
|
471 |
*/
|
jaroslav@1890
|
472 |
private int largestPoolSize;
|
jaroslav@1890
|
473 |
|
jaroslav@1890
|
474 |
/**
|
jaroslav@1890
|
475 |
* Counter for completed tasks. Updated only on termination of
|
jaroslav@1890
|
476 |
* worker threads. Accessed only under mainLock.
|
jaroslav@1890
|
477 |
*/
|
jaroslav@1890
|
478 |
private long completedTaskCount;
|
jaroslav@1890
|
479 |
|
jaroslav@1890
|
480 |
/*
|
jaroslav@1890
|
481 |
* All user control parameters are declared as volatiles so that
|
jaroslav@1890
|
482 |
* ongoing actions are based on freshest values, but without need
|
jaroslav@1890
|
483 |
* for locking, since no internal invariants depend on them
|
jaroslav@1890
|
484 |
* changing synchronously with respect to other actions.
|
jaroslav@1890
|
485 |
*/
|
jaroslav@1890
|
486 |
|
jaroslav@1890
|
487 |
/**
|
jaroslav@1890
|
488 |
* Factory for new threads. All threads are created using this
|
jaroslav@1890
|
489 |
* factory (via method addWorker). All callers must be prepared
|
jaroslav@1890
|
490 |
* for addWorker to fail, which may reflect a system or user's
|
jaroslav@1890
|
491 |
* policy limiting the number of threads. Even though it is not
|
jaroslav@1890
|
492 |
* treated as an error, failure to create threads may result in
|
jaroslav@1890
|
493 |
* new tasks being rejected or existing ones remaining stuck in
|
jaroslav@1890
|
494 |
* the queue. On the other hand, no special precautions exist to
|
jaroslav@1890
|
495 |
* handle OutOfMemoryErrors that might be thrown while trying to
|
jaroslav@1890
|
496 |
* create threads, since there is generally no recourse from
|
jaroslav@1890
|
497 |
* within this class.
|
jaroslav@1890
|
498 |
*/
|
jaroslav@1890
|
499 |
private volatile ThreadFactory threadFactory;
|
jaroslav@1890
|
500 |
|
jaroslav@1890
|
501 |
/**
|
jaroslav@1890
|
502 |
* Handler called when saturated or shutdown in execute.
|
jaroslav@1890
|
503 |
*/
|
jaroslav@1890
|
504 |
private volatile RejectedExecutionHandler handler;
|
jaroslav@1890
|
505 |
|
jaroslav@1890
|
506 |
/**
|
jaroslav@1890
|
507 |
* Timeout in nanoseconds for idle threads waiting for work.
|
jaroslav@1890
|
508 |
* Threads use this timeout when there are more than corePoolSize
|
jaroslav@1890
|
509 |
* present or if allowCoreThreadTimeOut. Otherwise they wait
|
jaroslav@1890
|
510 |
* forever for new work.
|
jaroslav@1890
|
511 |
*/
|
jaroslav@1890
|
512 |
private volatile long keepAliveTime;
|
jaroslav@1890
|
513 |
|
jaroslav@1890
|
514 |
/**
|
jaroslav@1890
|
515 |
* If false (default), core threads stay alive even when idle.
|
jaroslav@1890
|
516 |
* If true, core threads use keepAliveTime to time out waiting
|
jaroslav@1890
|
517 |
* for work.
|
jaroslav@1890
|
518 |
*/
|
jaroslav@1890
|
519 |
private volatile boolean allowCoreThreadTimeOut;
|
jaroslav@1890
|
520 |
|
jaroslav@1890
|
521 |
/**
|
jaroslav@1890
|
522 |
* Core pool size is the minimum number of workers to keep alive
|
jaroslav@1890
|
523 |
* (and not allow to time out etc) unless allowCoreThreadTimeOut
|
jaroslav@1890
|
524 |
* is set, in which case the minimum is zero.
|
jaroslav@1890
|
525 |
*/
|
jaroslav@1890
|
526 |
private volatile int corePoolSize;
|
jaroslav@1890
|
527 |
|
jaroslav@1890
|
528 |
/**
|
jaroslav@1890
|
529 |
* Maximum pool size. Note that the actual maximum is internally
|
jaroslav@1890
|
530 |
* bounded by CAPACITY.
|
jaroslav@1890
|
531 |
*/
|
jaroslav@1890
|
532 |
private volatile int maximumPoolSize;
|
jaroslav@1890
|
533 |
|
jaroslav@1890
|
534 |
/**
|
jaroslav@1890
|
535 |
* The default rejected execution handler
|
jaroslav@1890
|
536 |
*/
|
jaroslav@1890
|
537 |
private static final RejectedExecutionHandler defaultHandler =
|
jaroslav@1890
|
538 |
new AbortPolicy();
|
jaroslav@1890
|
539 |
|
jaroslav@1890
|
540 |
/**
|
jaroslav@1890
|
541 |
* Permission required for callers of shutdown and shutdownNow.
|
jaroslav@1890
|
542 |
* We additionally require (see checkShutdownAccess) that callers
|
jaroslav@1890
|
543 |
* have permission to actually interrupt threads in the worker set
|
jaroslav@1890
|
544 |
* (as governed by Thread.interrupt, which relies on
|
jaroslav@1890
|
545 |
* ThreadGroup.checkAccess, which in turn relies on
|
jaroslav@1890
|
546 |
* SecurityManager.checkAccess). Shutdowns are attempted only if
|
jaroslav@1890
|
547 |
* these checks pass.
|
jaroslav@1890
|
548 |
*
|
jaroslav@1890
|
549 |
* All actual invocations of Thread.interrupt (see
|
jaroslav@1890
|
550 |
* interruptIdleWorkers and interruptWorkers) ignore
|
jaroslav@1890
|
551 |
* SecurityExceptions, meaning that the attempted interrupts
|
jaroslav@1890
|
552 |
* silently fail. In the case of shutdown, they should not fail
|
jaroslav@1890
|
553 |
* unless the SecurityManager has inconsistent policies, sometimes
|
jaroslav@1890
|
554 |
* allowing access to a thread and sometimes not. In such cases,
|
jaroslav@1890
|
555 |
* failure to actually interrupt threads may disable or delay full
|
jaroslav@1890
|
556 |
* termination. Other uses of interruptIdleWorkers are advisory,
|
jaroslav@1890
|
557 |
* and failure to actually interrupt will merely delay response to
|
jaroslav@1890
|
558 |
* configuration changes so is not handled exceptionally.
|
jaroslav@1890
|
559 |
*/
|
jaroslav@1895
|
560 |
// private static final RuntimePermission shutdownPerm =
|
jaroslav@1895
|
561 |
// new RuntimePermission("modifyThread");
|
jaroslav@1890
|
562 |
|
jaroslav@1890
|
563 |
/**
|
jaroslav@1890
|
564 |
* Class Worker mainly maintains interrupt control state for
|
jaroslav@1890
|
565 |
* threads running tasks, along with other minor bookkeeping.
|
jaroslav@1890
|
566 |
* This class opportunistically extends AbstractQueuedSynchronizer
|
jaroslav@1890
|
567 |
* to simplify acquiring and releasing a lock surrounding each
|
jaroslav@1890
|
568 |
* task execution. This protects against interrupts that are
|
jaroslav@1890
|
569 |
* intended to wake up a worker thread waiting for a task from
|
jaroslav@1890
|
570 |
* instead interrupting a task being run. We implement a simple
|
jaroslav@1890
|
571 |
* non-reentrant mutual exclusion lock rather than use ReentrantLock
|
jaroslav@1890
|
572 |
* because we do not want worker tasks to be able to reacquire the
|
jaroslav@1890
|
573 |
* lock when they invoke pool control methods like setCorePoolSize.
|
jaroslav@1890
|
574 |
*/
|
jaroslav@1890
|
575 |
private final class Worker
|
jaroslav@1890
|
576 |
extends AbstractQueuedSynchronizer
|
jaroslav@1890
|
577 |
implements Runnable
|
jaroslav@1890
|
578 |
{
|
jaroslav@1890
|
579 |
/**
|
jaroslav@1890
|
580 |
* This class will never be serialized, but we provide a
|
jaroslav@1890
|
581 |
* serialVersionUID to suppress a javac warning.
|
jaroslav@1890
|
582 |
*/
|
jaroslav@1890
|
583 |
private static final long serialVersionUID = 6138294804551838833L;
|
jaroslav@1890
|
584 |
|
jaroslav@1890
|
585 |
/** Thread this worker is running in. Null if factory fails. */
|
jaroslav@1890
|
586 |
final Thread thread;
|
jaroslav@1890
|
587 |
/** Initial task to run. Possibly null. */
|
jaroslav@1890
|
588 |
Runnable firstTask;
|
jaroslav@1890
|
589 |
/** Per-thread task counter */
|
jaroslav@1890
|
590 |
volatile long completedTasks;
|
jaroslav@1890
|
591 |
|
jaroslav@1890
|
592 |
/**
|
jaroslav@1890
|
593 |
* Creates with given first task and thread from ThreadFactory.
|
jaroslav@1890
|
594 |
* @param firstTask the first task (null if none)
|
jaroslav@1890
|
595 |
*/
|
jaroslav@1890
|
596 |
Worker(Runnable firstTask) {
|
jaroslav@1890
|
597 |
this.firstTask = firstTask;
|
jaroslav@1890
|
598 |
this.thread = getThreadFactory().newThread(this);
|
jaroslav@1890
|
599 |
}
|
jaroslav@1890
|
600 |
|
jaroslav@1890
|
601 |
/** Delegates main run loop to outer runWorker */
|
jaroslav@1890
|
602 |
public void run() {
|
jaroslav@1890
|
603 |
runWorker(this);
|
jaroslav@1890
|
604 |
}
|
jaroslav@1890
|
605 |
|
jaroslav@1890
|
606 |
// Lock methods
|
jaroslav@1890
|
607 |
//
|
jaroslav@1890
|
608 |
// The value 0 represents the unlocked state.
|
jaroslav@1890
|
609 |
// The value 1 represents the locked state.
|
jaroslav@1890
|
610 |
|
jaroslav@1890
|
611 |
protected boolean isHeldExclusively() {
|
jaroslav@1890
|
612 |
return getState() == 1;
|
jaroslav@1890
|
613 |
}
|
jaroslav@1890
|
614 |
|
jaroslav@1890
|
615 |
protected boolean tryAcquire(int unused) {
|
jaroslav@1890
|
616 |
if (compareAndSetState(0, 1)) {
|
jaroslav@1890
|
617 |
setExclusiveOwnerThread(Thread.currentThread());
|
jaroslav@1890
|
618 |
return true;
|
jaroslav@1890
|
619 |
}
|
jaroslav@1890
|
620 |
return false;
|
jaroslav@1890
|
621 |
}
|
jaroslav@1890
|
622 |
|
jaroslav@1890
|
623 |
protected boolean tryRelease(int unused) {
|
jaroslav@1890
|
624 |
setExclusiveOwnerThread(null);
|
jaroslav@1890
|
625 |
setState(0);
|
jaroslav@1890
|
626 |
return true;
|
jaroslav@1890
|
627 |
}
|
jaroslav@1890
|
628 |
|
jaroslav@1890
|
629 |
public void lock() { acquire(1); }
|
jaroslav@1890
|
630 |
public boolean tryLock() { return tryAcquire(1); }
|
jaroslav@1890
|
631 |
public void unlock() { release(1); }
|
jaroslav@1890
|
632 |
public boolean isLocked() { return isHeldExclusively(); }
|
jaroslav@1890
|
633 |
}
|
jaroslav@1890
|
634 |
|
jaroslav@1890
|
635 |
/*
|
jaroslav@1890
|
636 |
* Methods for setting control state
|
jaroslav@1890
|
637 |
*/
|
jaroslav@1890
|
638 |
|
jaroslav@1890
|
639 |
/**
|
jaroslav@1890
|
640 |
* Transitions runState to given target, or leaves it alone if
|
jaroslav@1890
|
641 |
* already at least the given target.
|
jaroslav@1890
|
642 |
*
|
jaroslav@1890
|
643 |
* @param targetState the desired state, either SHUTDOWN or STOP
|
jaroslav@1890
|
644 |
* (but not TIDYING or TERMINATED -- use tryTerminate for that)
|
jaroslav@1890
|
645 |
*/
|
jaroslav@1890
|
646 |
private void advanceRunState(int targetState) {
|
jaroslav@1890
|
647 |
for (;;) {
|
jaroslav@1890
|
648 |
int c = ctl.get();
|
jaroslav@1890
|
649 |
if (runStateAtLeast(c, targetState) ||
|
jaroslav@1890
|
650 |
ctl.compareAndSet(c, ctlOf(targetState, workerCountOf(c))))
|
jaroslav@1890
|
651 |
break;
|
jaroslav@1890
|
652 |
}
|
jaroslav@1890
|
653 |
}
|
jaroslav@1890
|
654 |
|
jaroslav@1890
|
655 |
/**
|
jaroslav@1890
|
656 |
* Transitions to TERMINATED state if either (SHUTDOWN and pool
|
jaroslav@1890
|
657 |
* and queue empty) or (STOP and pool empty). If otherwise
|
jaroslav@1890
|
658 |
* eligible to terminate but workerCount is nonzero, interrupts an
|
jaroslav@1890
|
659 |
* idle worker to ensure that shutdown signals propagate. This
|
jaroslav@1890
|
660 |
* method must be called following any action that might make
|
jaroslav@1890
|
661 |
* termination possible -- reducing worker count or removing tasks
|
jaroslav@1890
|
662 |
* from the queue during shutdown. The method is non-private to
|
jaroslav@1890
|
663 |
* allow access from ScheduledThreadPoolExecutor.
|
jaroslav@1890
|
664 |
*/
|
jaroslav@1890
|
665 |
final void tryTerminate() {
|
jaroslav@1890
|
666 |
for (;;) {
|
jaroslav@1890
|
667 |
int c = ctl.get();
|
jaroslav@1890
|
668 |
if (isRunning(c) ||
|
jaroslav@1890
|
669 |
runStateAtLeast(c, TIDYING) ||
|
jaroslav@1890
|
670 |
(runStateOf(c) == SHUTDOWN && ! workQueue.isEmpty()))
|
jaroslav@1890
|
671 |
return;
|
jaroslav@1890
|
672 |
if (workerCountOf(c) != 0) { // Eligible to terminate
|
jaroslav@1890
|
673 |
interruptIdleWorkers(ONLY_ONE);
|
jaroslav@1890
|
674 |
return;
|
jaroslav@1890
|
675 |
}
|
jaroslav@1890
|
676 |
|
jaroslav@1890
|
677 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
678 |
mainLock.lock();
|
jaroslav@1890
|
679 |
try {
|
jaroslav@1890
|
680 |
if (ctl.compareAndSet(c, ctlOf(TIDYING, 0))) {
|
jaroslav@1890
|
681 |
try {
|
jaroslav@1890
|
682 |
terminated();
|
jaroslav@1890
|
683 |
} finally {
|
jaroslav@1890
|
684 |
ctl.set(ctlOf(TERMINATED, 0));
|
jaroslav@1890
|
685 |
termination.signalAll();
|
jaroslav@1890
|
686 |
}
|
jaroslav@1890
|
687 |
return;
|
jaroslav@1890
|
688 |
}
|
jaroslav@1890
|
689 |
} finally {
|
jaroslav@1890
|
690 |
mainLock.unlock();
|
jaroslav@1890
|
691 |
}
|
jaroslav@1890
|
692 |
// else retry on failed CAS
|
jaroslav@1890
|
693 |
}
|
jaroslav@1890
|
694 |
}
|
jaroslav@1890
|
695 |
|
jaroslav@1890
|
696 |
/*
|
jaroslav@1890
|
697 |
* Methods for controlling interrupts to worker threads.
|
jaroslav@1890
|
698 |
*/
|
jaroslav@1890
|
699 |
|
jaroslav@1890
|
700 |
/**
|
jaroslav@1890
|
701 |
* If there is a security manager, makes sure caller has
|
jaroslav@1890
|
702 |
* permission to shut down threads in general (see shutdownPerm).
|
jaroslav@1890
|
703 |
* If this passes, additionally makes sure the caller is allowed
|
jaroslav@1890
|
704 |
* to interrupt each worker thread. This might not be true even if
|
jaroslav@1890
|
705 |
* first check passed, if the SecurityManager treats some threads
|
jaroslav@1890
|
706 |
* specially.
|
jaroslav@1890
|
707 |
*/
|
jaroslav@1890
|
708 |
private void checkShutdownAccess() {
|
jaroslav@1895
|
709 |
// SecurityManager security = System.getSecurityManager();
|
jaroslav@1895
|
710 |
// if (security != null) {
|
jaroslav@1895
|
711 |
// security.checkPermission(shutdownPerm);
|
jaroslav@1895
|
712 |
// final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1895
|
713 |
// mainLock.lock();
|
jaroslav@1895
|
714 |
// try {
|
jaroslav@1895
|
715 |
// for (Worker w : workers)
|
jaroslav@1895
|
716 |
// security.checkAccess(w.thread);
|
jaroslav@1895
|
717 |
// } finally {
|
jaroslav@1895
|
718 |
// mainLock.unlock();
|
jaroslav@1895
|
719 |
// }
|
jaroslav@1895
|
720 |
// }
|
jaroslav@1890
|
721 |
}
|
jaroslav@1890
|
722 |
|
jaroslav@1890
|
723 |
/**
|
jaroslav@1890
|
724 |
* Interrupts all threads, even if active. Ignores SecurityExceptions
|
jaroslav@1890
|
725 |
* (in which case some threads may remain uninterrupted).
|
jaroslav@1890
|
726 |
*/
|
jaroslav@1890
|
727 |
private void interruptWorkers() {
|
jaroslav@1890
|
728 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
729 |
mainLock.lock();
|
jaroslav@1890
|
730 |
try {
|
jaroslav@1890
|
731 |
for (Worker w : workers) {
|
jaroslav@1890
|
732 |
try {
|
jaroslav@1890
|
733 |
w.thread.interrupt();
|
jaroslav@1890
|
734 |
} catch (SecurityException ignore) {
|
jaroslav@1890
|
735 |
}
|
jaroslav@1890
|
736 |
}
|
jaroslav@1890
|
737 |
} finally {
|
jaroslav@1890
|
738 |
mainLock.unlock();
|
jaroslav@1890
|
739 |
}
|
jaroslav@1890
|
740 |
}
|
jaroslav@1890
|
741 |
|
jaroslav@1890
|
742 |
/**
|
jaroslav@1890
|
743 |
* Interrupts threads that might be waiting for tasks (as
|
jaroslav@1890
|
744 |
* indicated by not being locked) so they can check for
|
jaroslav@1890
|
745 |
* termination or configuration changes. Ignores
|
jaroslav@1890
|
746 |
* SecurityExceptions (in which case some threads may remain
|
jaroslav@1890
|
747 |
* uninterrupted).
|
jaroslav@1890
|
748 |
*
|
jaroslav@1890
|
749 |
* @param onlyOne If true, interrupt at most one worker. This is
|
jaroslav@1890
|
750 |
* called only from tryTerminate when termination is otherwise
|
jaroslav@1890
|
751 |
* enabled but there are still other workers. In this case, at
|
jaroslav@1890
|
752 |
* most one waiting worker is interrupted to propagate shutdown
|
jaroslav@1890
|
753 |
* signals in case all threads are currently waiting.
|
jaroslav@1890
|
754 |
* Interrupting any arbitrary thread ensures that newly arriving
|
jaroslav@1890
|
755 |
* workers since shutdown began will also eventually exit.
|
jaroslav@1890
|
756 |
* To guarantee eventual termination, it suffices to always
|
jaroslav@1890
|
757 |
* interrupt only one idle worker, but shutdown() interrupts all
|
jaroslav@1890
|
758 |
* idle workers so that redundant workers exit promptly, not
|
jaroslav@1890
|
759 |
* waiting for a straggler task to finish.
|
jaroslav@1890
|
760 |
*/
|
jaroslav@1890
|
761 |
private void interruptIdleWorkers(boolean onlyOne) {
|
jaroslav@1890
|
762 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
763 |
mainLock.lock();
|
jaroslav@1890
|
764 |
try {
|
jaroslav@1890
|
765 |
for (Worker w : workers) {
|
jaroslav@1890
|
766 |
Thread t = w.thread;
|
jaroslav@1890
|
767 |
if (!t.isInterrupted() && w.tryLock()) {
|
jaroslav@1890
|
768 |
try {
|
jaroslav@1890
|
769 |
t.interrupt();
|
jaroslav@1890
|
770 |
} catch (SecurityException ignore) {
|
jaroslav@1890
|
771 |
} finally {
|
jaroslav@1890
|
772 |
w.unlock();
|
jaroslav@1890
|
773 |
}
|
jaroslav@1890
|
774 |
}
|
jaroslav@1890
|
775 |
if (onlyOne)
|
jaroslav@1890
|
776 |
break;
|
jaroslav@1890
|
777 |
}
|
jaroslav@1890
|
778 |
} finally {
|
jaroslav@1890
|
779 |
mainLock.unlock();
|
jaroslav@1890
|
780 |
}
|
jaroslav@1890
|
781 |
}
|
jaroslav@1890
|
782 |
|
jaroslav@1890
|
783 |
/**
|
jaroslav@1890
|
784 |
* Common form of interruptIdleWorkers, to avoid having to
|
jaroslav@1890
|
785 |
* remember what the boolean argument means.
|
jaroslav@1890
|
786 |
*/
|
jaroslav@1890
|
787 |
private void interruptIdleWorkers() {
|
jaroslav@1890
|
788 |
interruptIdleWorkers(false);
|
jaroslav@1890
|
789 |
}
|
jaroslav@1890
|
790 |
|
jaroslav@1890
|
791 |
private static final boolean ONLY_ONE = true;
|
jaroslav@1890
|
792 |
|
jaroslav@1890
|
793 |
/**
|
jaroslav@1890
|
794 |
* Ensures that unless the pool is stopping, the current thread
|
jaroslav@1890
|
795 |
* does not have its interrupt set. This requires a double-check
|
jaroslav@1890
|
796 |
* of state in case the interrupt was cleared concurrently with a
|
jaroslav@1890
|
797 |
* shutdownNow -- if so, the interrupt is re-enabled.
|
jaroslav@1890
|
798 |
*/
|
jaroslav@1890
|
799 |
private void clearInterruptsForTaskRun() {
|
jaroslav@1890
|
800 |
if (runStateLessThan(ctl.get(), STOP) &&
|
jaroslav@1890
|
801 |
Thread.interrupted() &&
|
jaroslav@1890
|
802 |
runStateAtLeast(ctl.get(), STOP))
|
jaroslav@1890
|
803 |
Thread.currentThread().interrupt();
|
jaroslav@1890
|
804 |
}
|
jaroslav@1890
|
805 |
|
jaroslav@1890
|
806 |
/*
|
jaroslav@1890
|
807 |
* Misc utilities, most of which are also exported to
|
jaroslav@1890
|
808 |
* ScheduledThreadPoolExecutor
|
jaroslav@1890
|
809 |
*/
|
jaroslav@1890
|
810 |
|
jaroslav@1890
|
811 |
/**
|
jaroslav@1890
|
812 |
* Invokes the rejected execution handler for the given command.
|
jaroslav@1890
|
813 |
* Package-protected for use by ScheduledThreadPoolExecutor.
|
jaroslav@1890
|
814 |
*/
|
jaroslav@1890
|
815 |
final void reject(Runnable command) {
|
jaroslav@1890
|
816 |
handler.rejectedExecution(command, this);
|
jaroslav@1890
|
817 |
}
|
jaroslav@1890
|
818 |
|
jaroslav@1890
|
819 |
/**
|
jaroslav@1890
|
820 |
* Performs any further cleanup following run state transition on
|
jaroslav@1890
|
821 |
* invocation of shutdown. A no-op here, but used by
|
jaroslav@1890
|
822 |
* ScheduledThreadPoolExecutor to cancel delayed tasks.
|
jaroslav@1890
|
823 |
*/
|
jaroslav@1890
|
824 |
void onShutdown() {
|
jaroslav@1890
|
825 |
}
|
jaroslav@1890
|
826 |
|
jaroslav@1890
|
827 |
/**
|
jaroslav@1890
|
828 |
* State check needed by ScheduledThreadPoolExecutor to
|
jaroslav@1890
|
829 |
* enable running tasks during shutdown.
|
jaroslav@1890
|
830 |
*
|
jaroslav@1890
|
831 |
* @param shutdownOK true if should return true if SHUTDOWN
|
jaroslav@1890
|
832 |
*/
|
jaroslav@1890
|
833 |
final boolean isRunningOrShutdown(boolean shutdownOK) {
|
jaroslav@1890
|
834 |
int rs = runStateOf(ctl.get());
|
jaroslav@1890
|
835 |
return rs == RUNNING || (rs == SHUTDOWN && shutdownOK);
|
jaroslav@1890
|
836 |
}
|
jaroslav@1890
|
837 |
|
jaroslav@1890
|
838 |
/**
|
jaroslav@1890
|
839 |
* Drains the task queue into a new list, normally using
|
jaroslav@1890
|
840 |
* drainTo. But if the queue is a DelayQueue or any other kind of
|
jaroslav@1890
|
841 |
* queue for which poll or drainTo may fail to remove some
|
jaroslav@1890
|
842 |
* elements, it deletes them one by one.
|
jaroslav@1890
|
843 |
*/
|
jaroslav@1890
|
844 |
private List<Runnable> drainQueue() {
|
jaroslav@1890
|
845 |
BlockingQueue<Runnable> q = workQueue;
|
jaroslav@1890
|
846 |
List<Runnable> taskList = new ArrayList<Runnable>();
|
jaroslav@1890
|
847 |
q.drainTo(taskList);
|
jaroslav@1890
|
848 |
if (!q.isEmpty()) {
|
jaroslav@1890
|
849 |
for (Runnable r : q.toArray(new Runnable[0])) {
|
jaroslav@1890
|
850 |
if (q.remove(r))
|
jaroslav@1890
|
851 |
taskList.add(r);
|
jaroslav@1890
|
852 |
}
|
jaroslav@1890
|
853 |
}
|
jaroslav@1890
|
854 |
return taskList;
|
jaroslav@1890
|
855 |
}
|
jaroslav@1890
|
856 |
|
jaroslav@1890
|
857 |
/*
|
jaroslav@1890
|
858 |
* Methods for creating, running and cleaning up after workers
|
jaroslav@1890
|
859 |
*/
|
jaroslav@1890
|
860 |
|
jaroslav@1890
|
861 |
/**
|
jaroslav@1890
|
862 |
* Checks if a new worker can be added with respect to current
|
jaroslav@1890
|
863 |
* pool state and the given bound (either core or maximum). If so,
|
jaroslav@1890
|
864 |
* the worker count is adjusted accordingly, and, if possible, a
|
jaroslav@1890
|
865 |
* new worker is created and started running firstTask as its
|
jaroslav@1890
|
866 |
* first task. This method returns false if the pool is stopped or
|
jaroslav@1890
|
867 |
* eligible to shut down. It also returns false if the thread
|
jaroslav@1890
|
868 |
* factory fails to create a thread when asked, which requires a
|
jaroslav@1890
|
869 |
* backout of workerCount, and a recheck for termination, in case
|
jaroslav@1890
|
870 |
* the existence of this worker was holding up termination.
|
jaroslav@1890
|
871 |
*
|
jaroslav@1890
|
872 |
* @param firstTask the task the new thread should run first (or
|
jaroslav@1890
|
873 |
* null if none). Workers are created with an initial first task
|
jaroslav@1890
|
874 |
* (in method execute()) to bypass queuing when there are fewer
|
jaroslav@1890
|
875 |
* than corePoolSize threads (in which case we always start one),
|
jaroslav@1890
|
876 |
* or when the queue is full (in which case we must bypass queue).
|
jaroslav@1890
|
877 |
* Initially idle threads are usually created via
|
jaroslav@1890
|
878 |
* prestartCoreThread or to replace other dying workers.
|
jaroslav@1890
|
879 |
*
|
jaroslav@1890
|
880 |
* @param core if true use corePoolSize as bound, else
|
jaroslav@1890
|
881 |
* maximumPoolSize. (A boolean indicator is used here rather than a
|
jaroslav@1890
|
882 |
* value to ensure reads of fresh values after checking other pool
|
jaroslav@1890
|
883 |
* state).
|
jaroslav@1890
|
884 |
* @return true if successful
|
jaroslav@1890
|
885 |
*/
|
jaroslav@1890
|
886 |
private boolean addWorker(Runnable firstTask, boolean core) {
|
jaroslav@1890
|
887 |
retry:
|
jaroslav@1890
|
888 |
for (;;) {
|
jaroslav@1890
|
889 |
int c = ctl.get();
|
jaroslav@1890
|
890 |
int rs = runStateOf(c);
|
jaroslav@1890
|
891 |
|
jaroslav@1890
|
892 |
// Check if queue empty only if necessary.
|
jaroslav@1890
|
893 |
if (rs >= SHUTDOWN &&
|
jaroslav@1890
|
894 |
! (rs == SHUTDOWN &&
|
jaroslav@1890
|
895 |
firstTask == null &&
|
jaroslav@1890
|
896 |
! workQueue.isEmpty()))
|
jaroslav@1890
|
897 |
return false;
|
jaroslav@1890
|
898 |
|
jaroslav@1890
|
899 |
for (;;) {
|
jaroslav@1890
|
900 |
int wc = workerCountOf(c);
|
jaroslav@1890
|
901 |
if (wc >= CAPACITY ||
|
jaroslav@1890
|
902 |
wc >= (core ? corePoolSize : maximumPoolSize))
|
jaroslav@1890
|
903 |
return false;
|
jaroslav@1890
|
904 |
if (compareAndIncrementWorkerCount(c))
|
jaroslav@1890
|
905 |
break retry;
|
jaroslav@1890
|
906 |
c = ctl.get(); // Re-read ctl
|
jaroslav@1890
|
907 |
if (runStateOf(c) != rs)
|
jaroslav@1890
|
908 |
continue retry;
|
jaroslav@1890
|
909 |
// else CAS failed due to workerCount change; retry inner loop
|
jaroslav@1890
|
910 |
}
|
jaroslav@1890
|
911 |
}
|
jaroslav@1890
|
912 |
|
jaroslav@1890
|
913 |
Worker w = new Worker(firstTask);
|
jaroslav@1890
|
914 |
Thread t = w.thread;
|
jaroslav@1890
|
915 |
|
jaroslav@1890
|
916 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
917 |
mainLock.lock();
|
jaroslav@1890
|
918 |
try {
|
jaroslav@1890
|
919 |
// Recheck while holding lock.
|
jaroslav@1890
|
920 |
// Back out on ThreadFactory failure or if
|
jaroslav@1890
|
921 |
// shut down before lock acquired.
|
jaroslav@1890
|
922 |
int c = ctl.get();
|
jaroslav@1890
|
923 |
int rs = runStateOf(c);
|
jaroslav@1890
|
924 |
|
jaroslav@1890
|
925 |
if (t == null ||
|
jaroslav@1890
|
926 |
(rs >= SHUTDOWN &&
|
jaroslav@1890
|
927 |
! (rs == SHUTDOWN &&
|
jaroslav@1890
|
928 |
firstTask == null))) {
|
jaroslav@1890
|
929 |
decrementWorkerCount();
|
jaroslav@1890
|
930 |
tryTerminate();
|
jaroslav@1890
|
931 |
return false;
|
jaroslav@1890
|
932 |
}
|
jaroslav@1890
|
933 |
|
jaroslav@1890
|
934 |
workers.add(w);
|
jaroslav@1890
|
935 |
|
jaroslav@1890
|
936 |
int s = workers.size();
|
jaroslav@1890
|
937 |
if (s > largestPoolSize)
|
jaroslav@1890
|
938 |
largestPoolSize = s;
|
jaroslav@1890
|
939 |
} finally {
|
jaroslav@1890
|
940 |
mainLock.unlock();
|
jaroslav@1890
|
941 |
}
|
jaroslav@1890
|
942 |
|
jaroslav@1890
|
943 |
t.start();
|
jaroslav@1890
|
944 |
// It is possible (but unlikely) for a thread to have been
|
jaroslav@1890
|
945 |
// added to workers, but not yet started, during transition to
|
jaroslav@1890
|
946 |
// STOP, which could result in a rare missed interrupt,
|
jaroslav@1890
|
947 |
// because Thread.interrupt is not guaranteed to have any effect
|
jaroslav@1890
|
948 |
// on a non-yet-started Thread (see Thread#interrupt).
|
jaroslav@1890
|
949 |
if (runStateOf(ctl.get()) == STOP && ! t.isInterrupted())
|
jaroslav@1890
|
950 |
t.interrupt();
|
jaroslav@1890
|
951 |
|
jaroslav@1890
|
952 |
return true;
|
jaroslav@1890
|
953 |
}
|
jaroslav@1890
|
954 |
|
jaroslav@1890
|
955 |
/**
|
jaroslav@1890
|
956 |
* Performs cleanup and bookkeeping for a dying worker. Called
|
jaroslav@1890
|
957 |
* only from worker threads. Unless completedAbruptly is set,
|
jaroslav@1890
|
958 |
* assumes that workerCount has already been adjusted to account
|
jaroslav@1890
|
959 |
* for exit. This method removes thread from worker set, and
|
jaroslav@1890
|
960 |
* possibly terminates the pool or replaces the worker if either
|
jaroslav@1890
|
961 |
* it exited due to user task exception or if fewer than
|
jaroslav@1890
|
962 |
* corePoolSize workers are running or queue is non-empty but
|
jaroslav@1890
|
963 |
* there are no workers.
|
jaroslav@1890
|
964 |
*
|
jaroslav@1890
|
965 |
* @param w the worker
|
jaroslav@1890
|
966 |
* @param completedAbruptly if the worker died due to user exception
|
jaroslav@1890
|
967 |
*/
|
jaroslav@1890
|
968 |
private void processWorkerExit(Worker w, boolean completedAbruptly) {
|
jaroslav@1890
|
969 |
if (completedAbruptly) // If abrupt, then workerCount wasn't adjusted
|
jaroslav@1890
|
970 |
decrementWorkerCount();
|
jaroslav@1890
|
971 |
|
jaroslav@1890
|
972 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
973 |
mainLock.lock();
|
jaroslav@1890
|
974 |
try {
|
jaroslav@1890
|
975 |
completedTaskCount += w.completedTasks;
|
jaroslav@1890
|
976 |
workers.remove(w);
|
jaroslav@1890
|
977 |
} finally {
|
jaroslav@1890
|
978 |
mainLock.unlock();
|
jaroslav@1890
|
979 |
}
|
jaroslav@1890
|
980 |
|
jaroslav@1890
|
981 |
tryTerminate();
|
jaroslav@1890
|
982 |
|
jaroslav@1890
|
983 |
int c = ctl.get();
|
jaroslav@1890
|
984 |
if (runStateLessThan(c, STOP)) {
|
jaroslav@1890
|
985 |
if (!completedAbruptly) {
|
jaroslav@1890
|
986 |
int min = allowCoreThreadTimeOut ? 0 : corePoolSize;
|
jaroslav@1890
|
987 |
if (min == 0 && ! workQueue.isEmpty())
|
jaroslav@1890
|
988 |
min = 1;
|
jaroslav@1890
|
989 |
if (workerCountOf(c) >= min)
|
jaroslav@1890
|
990 |
return; // replacement not needed
|
jaroslav@1890
|
991 |
}
|
jaroslav@1890
|
992 |
addWorker(null, false);
|
jaroslav@1890
|
993 |
}
|
jaroslav@1890
|
994 |
}
|
jaroslav@1890
|
995 |
|
jaroslav@1890
|
996 |
/**
|
jaroslav@1890
|
997 |
* Performs blocking or timed wait for a task, depending on
|
jaroslav@1890
|
998 |
* current configuration settings, or returns null if this worker
|
jaroslav@1890
|
999 |
* must exit because of any of:
|
jaroslav@1890
|
1000 |
* 1. There are more than maximumPoolSize workers (due to
|
jaroslav@1890
|
1001 |
* a call to setMaximumPoolSize).
|
jaroslav@1890
|
1002 |
* 2. The pool is stopped.
|
jaroslav@1890
|
1003 |
* 3. The pool is shutdown and the queue is empty.
|
jaroslav@1890
|
1004 |
* 4. This worker timed out waiting for a task, and timed-out
|
jaroslav@1890
|
1005 |
* workers are subject to termination (that is,
|
jaroslav@1890
|
1006 |
* {@code allowCoreThreadTimeOut || workerCount > corePoolSize})
|
jaroslav@1890
|
1007 |
* both before and after the timed wait.
|
jaroslav@1890
|
1008 |
*
|
jaroslav@1890
|
1009 |
* @return task, or null if the worker must exit, in which case
|
jaroslav@1890
|
1010 |
* workerCount is decremented
|
jaroslav@1890
|
1011 |
*/
|
jaroslav@1890
|
1012 |
private Runnable getTask() {
|
jaroslav@1890
|
1013 |
boolean timedOut = false; // Did the last poll() time out?
|
jaroslav@1890
|
1014 |
|
jaroslav@1890
|
1015 |
retry:
|
jaroslav@1890
|
1016 |
for (;;) {
|
jaroslav@1890
|
1017 |
int c = ctl.get();
|
jaroslav@1890
|
1018 |
int rs = runStateOf(c);
|
jaroslav@1890
|
1019 |
|
jaroslav@1890
|
1020 |
// Check if queue empty only if necessary.
|
jaroslav@1890
|
1021 |
if (rs >= SHUTDOWN && (rs >= STOP || workQueue.isEmpty())) {
|
jaroslav@1890
|
1022 |
decrementWorkerCount();
|
jaroslav@1890
|
1023 |
return null;
|
jaroslav@1890
|
1024 |
}
|
jaroslav@1890
|
1025 |
|
jaroslav@1890
|
1026 |
boolean timed; // Are workers subject to culling?
|
jaroslav@1890
|
1027 |
|
jaroslav@1890
|
1028 |
for (;;) {
|
jaroslav@1890
|
1029 |
int wc = workerCountOf(c);
|
jaroslav@1890
|
1030 |
timed = allowCoreThreadTimeOut || wc > corePoolSize;
|
jaroslav@1890
|
1031 |
|
jaroslav@1890
|
1032 |
if (wc <= maximumPoolSize && ! (timedOut && timed))
|
jaroslav@1890
|
1033 |
break;
|
jaroslav@1890
|
1034 |
if (compareAndDecrementWorkerCount(c))
|
jaroslav@1890
|
1035 |
return null;
|
jaroslav@1890
|
1036 |
c = ctl.get(); // Re-read ctl
|
jaroslav@1890
|
1037 |
if (runStateOf(c) != rs)
|
jaroslav@1890
|
1038 |
continue retry;
|
jaroslav@1890
|
1039 |
// else CAS failed due to workerCount change; retry inner loop
|
jaroslav@1890
|
1040 |
}
|
jaroslav@1890
|
1041 |
|
jaroslav@1890
|
1042 |
try {
|
jaroslav@1890
|
1043 |
Runnable r = timed ?
|
jaroslav@1890
|
1044 |
workQueue.poll(keepAliveTime, TimeUnit.NANOSECONDS) :
|
jaroslav@1890
|
1045 |
workQueue.take();
|
jaroslav@1890
|
1046 |
if (r != null)
|
jaroslav@1890
|
1047 |
return r;
|
jaroslav@1890
|
1048 |
timedOut = true;
|
jaroslav@1890
|
1049 |
} catch (InterruptedException retry) {
|
jaroslav@1890
|
1050 |
timedOut = false;
|
jaroslav@1890
|
1051 |
}
|
jaroslav@1890
|
1052 |
}
|
jaroslav@1890
|
1053 |
}
|
jaroslav@1890
|
1054 |
|
jaroslav@1890
|
1055 |
/**
|
jaroslav@1890
|
1056 |
* Main worker run loop. Repeatedly gets tasks from queue and
|
jaroslav@1890
|
1057 |
* executes them, while coping with a number of issues:
|
jaroslav@1890
|
1058 |
*
|
jaroslav@1890
|
1059 |
* 1. We may start out with an initial task, in which case we
|
jaroslav@1890
|
1060 |
* don't need to get the first one. Otherwise, as long as pool is
|
jaroslav@1890
|
1061 |
* running, we get tasks from getTask. If it returns null then the
|
jaroslav@1890
|
1062 |
* worker exits due to changed pool state or configuration
|
jaroslav@1890
|
1063 |
* parameters. Other exits result from exception throws in
|
jaroslav@1890
|
1064 |
* external code, in which case completedAbruptly holds, which
|
jaroslav@1890
|
1065 |
* usually leads processWorkerExit to replace this thread.
|
jaroslav@1890
|
1066 |
*
|
jaroslav@1890
|
1067 |
* 2. Before running any task, the lock is acquired to prevent
|
jaroslav@1890
|
1068 |
* other pool interrupts while the task is executing, and
|
jaroslav@1890
|
1069 |
* clearInterruptsForTaskRun called to ensure that unless pool is
|
jaroslav@1890
|
1070 |
* stopping, this thread does not have its interrupt set.
|
jaroslav@1890
|
1071 |
*
|
jaroslav@1890
|
1072 |
* 3. Each task run is preceded by a call to beforeExecute, which
|
jaroslav@1890
|
1073 |
* might throw an exception, in which case we cause thread to die
|
jaroslav@1890
|
1074 |
* (breaking loop with completedAbruptly true) without processing
|
jaroslav@1890
|
1075 |
* the task.
|
jaroslav@1890
|
1076 |
*
|
jaroslav@1890
|
1077 |
* 4. Assuming beforeExecute completes normally, we run the task,
|
jaroslav@1890
|
1078 |
* gathering any of its thrown exceptions to send to
|
jaroslav@1890
|
1079 |
* afterExecute. We separately handle RuntimeException, Error
|
jaroslav@1890
|
1080 |
* (both of which the specs guarantee that we trap) and arbitrary
|
jaroslav@1890
|
1081 |
* Throwables. Because we cannot rethrow Throwables within
|
jaroslav@1890
|
1082 |
* Runnable.run, we wrap them within Errors on the way out (to the
|
jaroslav@1890
|
1083 |
* thread's UncaughtExceptionHandler). Any thrown exception also
|
jaroslav@1890
|
1084 |
* conservatively causes thread to die.
|
jaroslav@1890
|
1085 |
*
|
jaroslav@1890
|
1086 |
* 5. After task.run completes, we call afterExecute, which may
|
jaroslav@1890
|
1087 |
* also throw an exception, which will also cause thread to
|
jaroslav@1890
|
1088 |
* die. According to JLS Sec 14.20, this exception is the one that
|
jaroslav@1890
|
1089 |
* will be in effect even if task.run throws.
|
jaroslav@1890
|
1090 |
*
|
jaroslav@1890
|
1091 |
* The net effect of the exception mechanics is that afterExecute
|
jaroslav@1890
|
1092 |
* and the thread's UncaughtExceptionHandler have as accurate
|
jaroslav@1890
|
1093 |
* information as we can provide about any problems encountered by
|
jaroslav@1890
|
1094 |
* user code.
|
jaroslav@1890
|
1095 |
*
|
jaroslav@1890
|
1096 |
* @param w the worker
|
jaroslav@1890
|
1097 |
*/
|
jaroslav@1890
|
1098 |
final void runWorker(Worker w) {
|
jaroslav@1890
|
1099 |
Runnable task = w.firstTask;
|
jaroslav@1890
|
1100 |
w.firstTask = null;
|
jaroslav@1890
|
1101 |
boolean completedAbruptly = true;
|
jaroslav@1890
|
1102 |
try {
|
jaroslav@1890
|
1103 |
while (task != null || (task = getTask()) != null) {
|
jaroslav@1890
|
1104 |
w.lock();
|
jaroslav@1890
|
1105 |
clearInterruptsForTaskRun();
|
jaroslav@1890
|
1106 |
try {
|
jaroslav@1890
|
1107 |
beforeExecute(w.thread, task);
|
jaroslav@1890
|
1108 |
Throwable thrown = null;
|
jaroslav@1890
|
1109 |
try {
|
jaroslav@1890
|
1110 |
task.run();
|
jaroslav@1890
|
1111 |
} catch (RuntimeException x) {
|
jaroslav@1890
|
1112 |
thrown = x; throw x;
|
jaroslav@1890
|
1113 |
} catch (Error x) {
|
jaroslav@1890
|
1114 |
thrown = x; throw x;
|
jaroslav@1890
|
1115 |
} catch (Throwable x) {
|
jaroslav@1890
|
1116 |
thrown = x; throw new Error(x);
|
jaroslav@1890
|
1117 |
} finally {
|
jaroslav@1890
|
1118 |
afterExecute(task, thrown);
|
jaroslav@1890
|
1119 |
}
|
jaroslav@1890
|
1120 |
} finally {
|
jaroslav@1890
|
1121 |
task = null;
|
jaroslav@1890
|
1122 |
w.completedTasks++;
|
jaroslav@1890
|
1123 |
w.unlock();
|
jaroslav@1890
|
1124 |
}
|
jaroslav@1890
|
1125 |
}
|
jaroslav@1890
|
1126 |
completedAbruptly = false;
|
jaroslav@1890
|
1127 |
} finally {
|
jaroslav@1890
|
1128 |
processWorkerExit(w, completedAbruptly);
|
jaroslav@1890
|
1129 |
}
|
jaroslav@1890
|
1130 |
}
|
jaroslav@1890
|
1131 |
|
jaroslav@1890
|
1132 |
// Public constructors and methods
|
jaroslav@1890
|
1133 |
|
jaroslav@1890
|
1134 |
/**
|
jaroslav@1890
|
1135 |
* Creates a new {@code ThreadPoolExecutor} with the given initial
|
jaroslav@1890
|
1136 |
* parameters and default thread factory and rejected execution handler.
|
jaroslav@1890
|
1137 |
* It may be more convenient to use one of the {@link Executors} factory
|
jaroslav@1890
|
1138 |
* methods instead of this general purpose constructor.
|
jaroslav@1890
|
1139 |
*
|
jaroslav@1890
|
1140 |
* @param corePoolSize the number of threads to keep in the pool, even
|
jaroslav@1890
|
1141 |
* if they are idle, unless {@code allowCoreThreadTimeOut} is set
|
jaroslav@1890
|
1142 |
* @param maximumPoolSize the maximum number of threads to allow in the
|
jaroslav@1890
|
1143 |
* pool
|
jaroslav@1890
|
1144 |
* @param keepAliveTime when the number of threads is greater than
|
jaroslav@1890
|
1145 |
* the core, this is the maximum time that excess idle threads
|
jaroslav@1890
|
1146 |
* will wait for new tasks before terminating.
|
jaroslav@1890
|
1147 |
* @param unit the time unit for the {@code keepAliveTime} argument
|
jaroslav@1890
|
1148 |
* @param workQueue the queue to use for holding tasks before they are
|
jaroslav@1890
|
1149 |
* executed. This queue will hold only the {@code Runnable}
|
jaroslav@1890
|
1150 |
* tasks submitted by the {@code execute} method.
|
jaroslav@1890
|
1151 |
* @throws IllegalArgumentException if one of the following holds:<br>
|
jaroslav@1890
|
1152 |
* {@code corePoolSize < 0}<br>
|
jaroslav@1890
|
1153 |
* {@code keepAliveTime < 0}<br>
|
jaroslav@1890
|
1154 |
* {@code maximumPoolSize <= 0}<br>
|
jaroslav@1890
|
1155 |
* {@code maximumPoolSize < corePoolSize}
|
jaroslav@1890
|
1156 |
* @throws NullPointerException if {@code workQueue} is null
|
jaroslav@1890
|
1157 |
*/
|
jaroslav@1890
|
1158 |
public ThreadPoolExecutor(int corePoolSize,
|
jaroslav@1890
|
1159 |
int maximumPoolSize,
|
jaroslav@1890
|
1160 |
long keepAliveTime,
|
jaroslav@1890
|
1161 |
TimeUnit unit,
|
jaroslav@1890
|
1162 |
BlockingQueue<Runnable> workQueue) {
|
jaroslav@1890
|
1163 |
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
|
jaroslav@1890
|
1164 |
Executors.defaultThreadFactory(), defaultHandler);
|
jaroslav@1890
|
1165 |
}
|
jaroslav@1890
|
1166 |
|
jaroslav@1890
|
1167 |
/**
|
jaroslav@1890
|
1168 |
* Creates a new {@code ThreadPoolExecutor} with the given initial
|
jaroslav@1890
|
1169 |
* parameters and default rejected execution handler.
|
jaroslav@1890
|
1170 |
*
|
jaroslav@1890
|
1171 |
* @param corePoolSize the number of threads to keep in the pool, even
|
jaroslav@1890
|
1172 |
* if they are idle, unless {@code allowCoreThreadTimeOut} is set
|
jaroslav@1890
|
1173 |
* @param maximumPoolSize the maximum number of threads to allow in the
|
jaroslav@1890
|
1174 |
* pool
|
jaroslav@1890
|
1175 |
* @param keepAliveTime when the number of threads is greater than
|
jaroslav@1890
|
1176 |
* the core, this is the maximum time that excess idle threads
|
jaroslav@1890
|
1177 |
* will wait for new tasks before terminating.
|
jaroslav@1890
|
1178 |
* @param unit the time unit for the {@code keepAliveTime} argument
|
jaroslav@1890
|
1179 |
* @param workQueue the queue to use for holding tasks before they are
|
jaroslav@1890
|
1180 |
* executed. This queue will hold only the {@code Runnable}
|
jaroslav@1890
|
1181 |
* tasks submitted by the {@code execute} method.
|
jaroslav@1890
|
1182 |
* @param threadFactory the factory to use when the executor
|
jaroslav@1890
|
1183 |
* creates a new thread
|
jaroslav@1890
|
1184 |
* @throws IllegalArgumentException if one of the following holds:<br>
|
jaroslav@1890
|
1185 |
* {@code corePoolSize < 0}<br>
|
jaroslav@1890
|
1186 |
* {@code keepAliveTime < 0}<br>
|
jaroslav@1890
|
1187 |
* {@code maximumPoolSize <= 0}<br>
|
jaroslav@1890
|
1188 |
* {@code maximumPoolSize < corePoolSize}
|
jaroslav@1890
|
1189 |
* @throws NullPointerException if {@code workQueue}
|
jaroslav@1890
|
1190 |
* or {@code threadFactory} is null
|
jaroslav@1890
|
1191 |
*/
|
jaroslav@1890
|
1192 |
public ThreadPoolExecutor(int corePoolSize,
|
jaroslav@1890
|
1193 |
int maximumPoolSize,
|
jaroslav@1890
|
1194 |
long keepAliveTime,
|
jaroslav@1890
|
1195 |
TimeUnit unit,
|
jaroslav@1890
|
1196 |
BlockingQueue<Runnable> workQueue,
|
jaroslav@1890
|
1197 |
ThreadFactory threadFactory) {
|
jaroslav@1890
|
1198 |
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
|
jaroslav@1890
|
1199 |
threadFactory, defaultHandler);
|
jaroslav@1890
|
1200 |
}
|
jaroslav@1890
|
1201 |
|
jaroslav@1890
|
1202 |
/**
|
jaroslav@1890
|
1203 |
* Creates a new {@code ThreadPoolExecutor} with the given initial
|
jaroslav@1890
|
1204 |
* parameters and default thread factory.
|
jaroslav@1890
|
1205 |
*
|
jaroslav@1890
|
1206 |
* @param corePoolSize the number of threads to keep in the pool, even
|
jaroslav@1890
|
1207 |
* if they are idle, unless {@code allowCoreThreadTimeOut} is set
|
jaroslav@1890
|
1208 |
* @param maximumPoolSize the maximum number of threads to allow in the
|
jaroslav@1890
|
1209 |
* pool
|
jaroslav@1890
|
1210 |
* @param keepAliveTime when the number of threads is greater than
|
jaroslav@1890
|
1211 |
* the core, this is the maximum time that excess idle threads
|
jaroslav@1890
|
1212 |
* will wait for new tasks before terminating.
|
jaroslav@1890
|
1213 |
* @param unit the time unit for the {@code keepAliveTime} argument
|
jaroslav@1890
|
1214 |
* @param workQueue the queue to use for holding tasks before they are
|
jaroslav@1890
|
1215 |
* executed. This queue will hold only the {@code Runnable}
|
jaroslav@1890
|
1216 |
* tasks submitted by the {@code execute} method.
|
jaroslav@1890
|
1217 |
* @param handler the handler to use when execution is blocked
|
jaroslav@1890
|
1218 |
* because the thread bounds and queue capacities are reached
|
jaroslav@1890
|
1219 |
* @throws IllegalArgumentException if one of the following holds:<br>
|
jaroslav@1890
|
1220 |
* {@code corePoolSize < 0}<br>
|
jaroslav@1890
|
1221 |
* {@code keepAliveTime < 0}<br>
|
jaroslav@1890
|
1222 |
* {@code maximumPoolSize <= 0}<br>
|
jaroslav@1890
|
1223 |
* {@code maximumPoolSize < corePoolSize}
|
jaroslav@1890
|
1224 |
* @throws NullPointerException if {@code workQueue}
|
jaroslav@1890
|
1225 |
* or {@code handler} is null
|
jaroslav@1890
|
1226 |
*/
|
jaroslav@1890
|
1227 |
public ThreadPoolExecutor(int corePoolSize,
|
jaroslav@1890
|
1228 |
int maximumPoolSize,
|
jaroslav@1890
|
1229 |
long keepAliveTime,
|
jaroslav@1890
|
1230 |
TimeUnit unit,
|
jaroslav@1890
|
1231 |
BlockingQueue<Runnable> workQueue,
|
jaroslav@1890
|
1232 |
RejectedExecutionHandler handler) {
|
jaroslav@1890
|
1233 |
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
|
jaroslav@1890
|
1234 |
Executors.defaultThreadFactory(), handler);
|
jaroslav@1890
|
1235 |
}
|
jaroslav@1890
|
1236 |
|
jaroslav@1890
|
1237 |
/**
|
jaroslav@1890
|
1238 |
* Creates a new {@code ThreadPoolExecutor} with the given initial
|
jaroslav@1890
|
1239 |
* parameters.
|
jaroslav@1890
|
1240 |
*
|
jaroslav@1890
|
1241 |
* @param corePoolSize the number of threads to keep in the pool, even
|
jaroslav@1890
|
1242 |
* if they are idle, unless {@code allowCoreThreadTimeOut} is set
|
jaroslav@1890
|
1243 |
* @param maximumPoolSize the maximum number of threads to allow in the
|
jaroslav@1890
|
1244 |
* pool
|
jaroslav@1890
|
1245 |
* @param keepAliveTime when the number of threads is greater than
|
jaroslav@1890
|
1246 |
* the core, this is the maximum time that excess idle threads
|
jaroslav@1890
|
1247 |
* will wait for new tasks before terminating.
|
jaroslav@1890
|
1248 |
* @param unit the time unit for the {@code keepAliveTime} argument
|
jaroslav@1890
|
1249 |
* @param workQueue the queue to use for holding tasks before they are
|
jaroslav@1890
|
1250 |
* executed. This queue will hold only the {@code Runnable}
|
jaroslav@1890
|
1251 |
* tasks submitted by the {@code execute} method.
|
jaroslav@1890
|
1252 |
* @param threadFactory the factory to use when the executor
|
jaroslav@1890
|
1253 |
* creates a new thread
|
jaroslav@1890
|
1254 |
* @param handler the handler to use when execution is blocked
|
jaroslav@1890
|
1255 |
* because the thread bounds and queue capacities are reached
|
jaroslav@1890
|
1256 |
* @throws IllegalArgumentException if one of the following holds:<br>
|
jaroslav@1890
|
1257 |
* {@code corePoolSize < 0}<br>
|
jaroslav@1890
|
1258 |
* {@code keepAliveTime < 0}<br>
|
jaroslav@1890
|
1259 |
* {@code maximumPoolSize <= 0}<br>
|
jaroslav@1890
|
1260 |
* {@code maximumPoolSize < corePoolSize}
|
jaroslav@1890
|
1261 |
* @throws NullPointerException if {@code workQueue}
|
jaroslav@1890
|
1262 |
* or {@code threadFactory} or {@code handler} is null
|
jaroslav@1890
|
1263 |
*/
|
jaroslav@1890
|
1264 |
public ThreadPoolExecutor(int corePoolSize,
|
jaroslav@1890
|
1265 |
int maximumPoolSize,
|
jaroslav@1890
|
1266 |
long keepAliveTime,
|
jaroslav@1890
|
1267 |
TimeUnit unit,
|
jaroslav@1890
|
1268 |
BlockingQueue<Runnable> workQueue,
|
jaroslav@1890
|
1269 |
ThreadFactory threadFactory,
|
jaroslav@1890
|
1270 |
RejectedExecutionHandler handler) {
|
jaroslav@1890
|
1271 |
if (corePoolSize < 0 ||
|
jaroslav@1890
|
1272 |
maximumPoolSize <= 0 ||
|
jaroslav@1890
|
1273 |
maximumPoolSize < corePoolSize ||
|
jaroslav@1890
|
1274 |
keepAliveTime < 0)
|
jaroslav@1890
|
1275 |
throw new IllegalArgumentException();
|
jaroslav@1890
|
1276 |
if (workQueue == null || threadFactory == null || handler == null)
|
jaroslav@1890
|
1277 |
throw new NullPointerException();
|
jaroslav@1890
|
1278 |
this.corePoolSize = corePoolSize;
|
jaroslav@1890
|
1279 |
this.maximumPoolSize = maximumPoolSize;
|
jaroslav@1890
|
1280 |
this.workQueue = workQueue;
|
jaroslav@1890
|
1281 |
this.keepAliveTime = unit.toNanos(keepAliveTime);
|
jaroslav@1890
|
1282 |
this.threadFactory = threadFactory;
|
jaroslav@1890
|
1283 |
this.handler = handler;
|
jaroslav@1890
|
1284 |
}
|
jaroslav@1890
|
1285 |
|
jaroslav@1890
|
1286 |
/**
|
jaroslav@1890
|
1287 |
* Executes the given task sometime in the future. The task
|
jaroslav@1890
|
1288 |
* may execute in a new thread or in an existing pooled thread.
|
jaroslav@1890
|
1289 |
*
|
jaroslav@1890
|
1290 |
* If the task cannot be submitted for execution, either because this
|
jaroslav@1890
|
1291 |
* executor has been shutdown or because its capacity has been reached,
|
jaroslav@1890
|
1292 |
* the task is handled by the current {@code RejectedExecutionHandler}.
|
jaroslav@1890
|
1293 |
*
|
jaroslav@1890
|
1294 |
* @param command the task to execute
|
jaroslav@1890
|
1295 |
* @throws RejectedExecutionException at discretion of
|
jaroslav@1890
|
1296 |
* {@code RejectedExecutionHandler}, if the task
|
jaroslav@1890
|
1297 |
* cannot be accepted for execution
|
jaroslav@1890
|
1298 |
* @throws NullPointerException if {@code command} is null
|
jaroslav@1890
|
1299 |
*/
|
jaroslav@1890
|
1300 |
public void execute(Runnable command) {
|
jaroslav@1890
|
1301 |
if (command == null)
|
jaroslav@1890
|
1302 |
throw new NullPointerException();
|
jaroslav@1890
|
1303 |
/*
|
jaroslav@1890
|
1304 |
* Proceed in 3 steps:
|
jaroslav@1890
|
1305 |
*
|
jaroslav@1890
|
1306 |
* 1. If fewer than corePoolSize threads are running, try to
|
jaroslav@1890
|
1307 |
* start a new thread with the given command as its first
|
jaroslav@1890
|
1308 |
* task. The call to addWorker atomically checks runState and
|
jaroslav@1890
|
1309 |
* workerCount, and so prevents false alarms that would add
|
jaroslav@1890
|
1310 |
* threads when it shouldn't, by returning false.
|
jaroslav@1890
|
1311 |
*
|
jaroslav@1890
|
1312 |
* 2. If a task can be successfully queued, then we still need
|
jaroslav@1890
|
1313 |
* to double-check whether we should have added a thread
|
jaroslav@1890
|
1314 |
* (because existing ones died since last checking) or that
|
jaroslav@1890
|
1315 |
* the pool shut down since entry into this method. So we
|
jaroslav@1890
|
1316 |
* recheck state and if necessary roll back the enqueuing if
|
jaroslav@1890
|
1317 |
* stopped, or start a new thread if there are none.
|
jaroslav@1890
|
1318 |
*
|
jaroslav@1890
|
1319 |
* 3. If we cannot queue task, then we try to add a new
|
jaroslav@1890
|
1320 |
* thread. If it fails, we know we are shut down or saturated
|
jaroslav@1890
|
1321 |
* and so reject the task.
|
jaroslav@1890
|
1322 |
*/
|
jaroslav@1890
|
1323 |
int c = ctl.get();
|
jaroslav@1890
|
1324 |
if (workerCountOf(c) < corePoolSize) {
|
jaroslav@1890
|
1325 |
if (addWorker(command, true))
|
jaroslav@1890
|
1326 |
return;
|
jaroslav@1890
|
1327 |
c = ctl.get();
|
jaroslav@1890
|
1328 |
}
|
jaroslav@1890
|
1329 |
if (isRunning(c) && workQueue.offer(command)) {
|
jaroslav@1890
|
1330 |
int recheck = ctl.get();
|
jaroslav@1890
|
1331 |
if (! isRunning(recheck) && remove(command))
|
jaroslav@1890
|
1332 |
reject(command);
|
jaroslav@1890
|
1333 |
else if (workerCountOf(recheck) == 0)
|
jaroslav@1890
|
1334 |
addWorker(null, false);
|
jaroslav@1890
|
1335 |
}
|
jaroslav@1890
|
1336 |
else if (!addWorker(command, false))
|
jaroslav@1890
|
1337 |
reject(command);
|
jaroslav@1890
|
1338 |
}
|
jaroslav@1890
|
1339 |
|
jaroslav@1890
|
1340 |
/**
|
jaroslav@1890
|
1341 |
* Initiates an orderly shutdown in which previously submitted
|
jaroslav@1890
|
1342 |
* tasks are executed, but no new tasks will be accepted.
|
jaroslav@1890
|
1343 |
* Invocation has no additional effect if already shut down.
|
jaroslav@1890
|
1344 |
*
|
jaroslav@1890
|
1345 |
* <p>This method does not wait for previously submitted tasks to
|
jaroslav@1890
|
1346 |
* complete execution. Use {@link #awaitTermination awaitTermination}
|
jaroslav@1890
|
1347 |
* to do that.
|
jaroslav@1890
|
1348 |
*
|
jaroslav@1890
|
1349 |
* @throws SecurityException {@inheritDoc}
|
jaroslav@1890
|
1350 |
*/
|
jaroslav@1890
|
1351 |
public void shutdown() {
|
jaroslav@1890
|
1352 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
1353 |
mainLock.lock();
|
jaroslav@1890
|
1354 |
try {
|
jaroslav@1890
|
1355 |
checkShutdownAccess();
|
jaroslav@1890
|
1356 |
advanceRunState(SHUTDOWN);
|
jaroslav@1890
|
1357 |
interruptIdleWorkers();
|
jaroslav@1890
|
1358 |
onShutdown(); // hook for ScheduledThreadPoolExecutor
|
jaroslav@1890
|
1359 |
} finally {
|
jaroslav@1890
|
1360 |
mainLock.unlock();
|
jaroslav@1890
|
1361 |
}
|
jaroslav@1890
|
1362 |
tryTerminate();
|
jaroslav@1890
|
1363 |
}
|
jaroslav@1890
|
1364 |
|
jaroslav@1890
|
1365 |
/**
|
jaroslav@1890
|
1366 |
* Attempts to stop all actively executing tasks, halts the
|
jaroslav@1890
|
1367 |
* processing of waiting tasks, and returns a list of the tasks
|
jaroslav@1890
|
1368 |
* that were awaiting execution. These tasks are drained (removed)
|
jaroslav@1890
|
1369 |
* from the task queue upon return from this method.
|
jaroslav@1890
|
1370 |
*
|
jaroslav@1890
|
1371 |
* <p>This method does not wait for actively executing tasks to
|
jaroslav@1890
|
1372 |
* terminate. Use {@link #awaitTermination awaitTermination} to
|
jaroslav@1890
|
1373 |
* do that.
|
jaroslav@1890
|
1374 |
*
|
jaroslav@1890
|
1375 |
* <p>There are no guarantees beyond best-effort attempts to stop
|
jaroslav@1890
|
1376 |
* processing actively executing tasks. This implementation
|
jaroslav@1890
|
1377 |
* cancels tasks via {@link Thread#interrupt}, so any task that
|
jaroslav@1890
|
1378 |
* fails to respond to interrupts may never terminate.
|
jaroslav@1890
|
1379 |
*
|
jaroslav@1890
|
1380 |
* @throws SecurityException {@inheritDoc}
|
jaroslav@1890
|
1381 |
*/
|
jaroslav@1890
|
1382 |
public List<Runnable> shutdownNow() {
|
jaroslav@1890
|
1383 |
List<Runnable> tasks;
|
jaroslav@1890
|
1384 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
1385 |
mainLock.lock();
|
jaroslav@1890
|
1386 |
try {
|
jaroslav@1890
|
1387 |
checkShutdownAccess();
|
jaroslav@1890
|
1388 |
advanceRunState(STOP);
|
jaroslav@1890
|
1389 |
interruptWorkers();
|
jaroslav@1890
|
1390 |
tasks = drainQueue();
|
jaroslav@1890
|
1391 |
} finally {
|
jaroslav@1890
|
1392 |
mainLock.unlock();
|
jaroslav@1890
|
1393 |
}
|
jaroslav@1890
|
1394 |
tryTerminate();
|
jaroslav@1890
|
1395 |
return tasks;
|
jaroslav@1890
|
1396 |
}
|
jaroslav@1890
|
1397 |
|
jaroslav@1890
|
1398 |
public boolean isShutdown() {
|
jaroslav@1890
|
1399 |
return ! isRunning(ctl.get());
|
jaroslav@1890
|
1400 |
}
|
jaroslav@1890
|
1401 |
|
jaroslav@1890
|
1402 |
/**
|
jaroslav@1890
|
1403 |
* Returns true if this executor is in the process of terminating
|
jaroslav@1890
|
1404 |
* after {@link #shutdown} or {@link #shutdownNow} but has not
|
jaroslav@1890
|
1405 |
* completely terminated. This method may be useful for
|
jaroslav@1890
|
1406 |
* debugging. A return of {@code true} reported a sufficient
|
jaroslav@1890
|
1407 |
* period after shutdown may indicate that submitted tasks have
|
jaroslav@1890
|
1408 |
* ignored or suppressed interruption, causing this executor not
|
jaroslav@1890
|
1409 |
* to properly terminate.
|
jaroslav@1890
|
1410 |
*
|
jaroslav@1890
|
1411 |
* @return true if terminating but not yet terminated
|
jaroslav@1890
|
1412 |
*/
|
jaroslav@1890
|
1413 |
public boolean isTerminating() {
|
jaroslav@1890
|
1414 |
int c = ctl.get();
|
jaroslav@1890
|
1415 |
return ! isRunning(c) && runStateLessThan(c, TERMINATED);
|
jaroslav@1890
|
1416 |
}
|
jaroslav@1890
|
1417 |
|
jaroslav@1890
|
1418 |
public boolean isTerminated() {
|
jaroslav@1890
|
1419 |
return runStateAtLeast(ctl.get(), TERMINATED);
|
jaroslav@1890
|
1420 |
}
|
jaroslav@1890
|
1421 |
|
jaroslav@1890
|
1422 |
public boolean awaitTermination(long timeout, TimeUnit unit)
|
jaroslav@1890
|
1423 |
throws InterruptedException {
|
jaroslav@1890
|
1424 |
long nanos = unit.toNanos(timeout);
|
jaroslav@1890
|
1425 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
1426 |
mainLock.lock();
|
jaroslav@1890
|
1427 |
try {
|
jaroslav@1890
|
1428 |
for (;;) {
|
jaroslav@1890
|
1429 |
if (runStateAtLeast(ctl.get(), TERMINATED))
|
jaroslav@1890
|
1430 |
return true;
|
jaroslav@1890
|
1431 |
if (nanos <= 0)
|
jaroslav@1890
|
1432 |
return false;
|
jaroslav@1890
|
1433 |
nanos = termination.awaitNanos(nanos);
|
jaroslav@1890
|
1434 |
}
|
jaroslav@1890
|
1435 |
} finally {
|
jaroslav@1890
|
1436 |
mainLock.unlock();
|
jaroslav@1890
|
1437 |
}
|
jaroslav@1890
|
1438 |
}
|
jaroslav@1890
|
1439 |
|
jaroslav@1890
|
1440 |
/**
|
jaroslav@1890
|
1441 |
* Invokes {@code shutdown} when this executor is no longer
|
jaroslav@1890
|
1442 |
* referenced and it has no threads.
|
jaroslav@1890
|
1443 |
*/
|
jaroslav@1890
|
1444 |
protected void finalize() {
|
jaroslav@1890
|
1445 |
shutdown();
|
jaroslav@1890
|
1446 |
}
|
jaroslav@1890
|
1447 |
|
jaroslav@1890
|
1448 |
/**
|
jaroslav@1890
|
1449 |
* Sets the thread factory used to create new threads.
|
jaroslav@1890
|
1450 |
*
|
jaroslav@1890
|
1451 |
* @param threadFactory the new thread factory
|
jaroslav@1890
|
1452 |
* @throws NullPointerException if threadFactory is null
|
jaroslav@1890
|
1453 |
* @see #getThreadFactory
|
jaroslav@1890
|
1454 |
*/
|
jaroslav@1890
|
1455 |
public void setThreadFactory(ThreadFactory threadFactory) {
|
jaroslav@1890
|
1456 |
if (threadFactory == null)
|
jaroslav@1890
|
1457 |
throw new NullPointerException();
|
jaroslav@1890
|
1458 |
this.threadFactory = threadFactory;
|
jaroslav@1890
|
1459 |
}
|
jaroslav@1890
|
1460 |
|
jaroslav@1890
|
1461 |
/**
|
jaroslav@1890
|
1462 |
* Returns the thread factory used to create new threads.
|
jaroslav@1890
|
1463 |
*
|
jaroslav@1890
|
1464 |
* @return the current thread factory
|
jaroslav@1890
|
1465 |
* @see #setThreadFactory
|
jaroslav@1890
|
1466 |
*/
|
jaroslav@1890
|
1467 |
public ThreadFactory getThreadFactory() {
|
jaroslav@1890
|
1468 |
return threadFactory;
|
jaroslav@1890
|
1469 |
}
|
jaroslav@1890
|
1470 |
|
jaroslav@1890
|
1471 |
/**
|
jaroslav@1890
|
1472 |
* Sets a new handler for unexecutable tasks.
|
jaroslav@1890
|
1473 |
*
|
jaroslav@1890
|
1474 |
* @param handler the new handler
|
jaroslav@1890
|
1475 |
* @throws NullPointerException if handler is null
|
jaroslav@1890
|
1476 |
* @see #getRejectedExecutionHandler
|
jaroslav@1890
|
1477 |
*/
|
jaroslav@1890
|
1478 |
public void setRejectedExecutionHandler(RejectedExecutionHandler handler) {
|
jaroslav@1890
|
1479 |
if (handler == null)
|
jaroslav@1890
|
1480 |
throw new NullPointerException();
|
jaroslav@1890
|
1481 |
this.handler = handler;
|
jaroslav@1890
|
1482 |
}
|
jaroslav@1890
|
1483 |
|
jaroslav@1890
|
1484 |
/**
|
jaroslav@1890
|
1485 |
* Returns the current handler for unexecutable tasks.
|
jaroslav@1890
|
1486 |
*
|
jaroslav@1890
|
1487 |
* @return the current handler
|
jaroslav@1890
|
1488 |
* @see #setRejectedExecutionHandler
|
jaroslav@1890
|
1489 |
*/
|
jaroslav@1890
|
1490 |
public RejectedExecutionHandler getRejectedExecutionHandler() {
|
jaroslav@1890
|
1491 |
return handler;
|
jaroslav@1890
|
1492 |
}
|
jaroslav@1890
|
1493 |
|
jaroslav@1890
|
1494 |
/**
|
jaroslav@1890
|
1495 |
* Sets the core number of threads. This overrides any value set
|
jaroslav@1890
|
1496 |
* in the constructor. If the new value is smaller than the
|
jaroslav@1890
|
1497 |
* current value, excess existing threads will be terminated when
|
jaroslav@1890
|
1498 |
* they next become idle. If larger, new threads will, if needed,
|
jaroslav@1890
|
1499 |
* be started to execute any queued tasks.
|
jaroslav@1890
|
1500 |
*
|
jaroslav@1890
|
1501 |
* @param corePoolSize the new core size
|
jaroslav@1890
|
1502 |
* @throws IllegalArgumentException if {@code corePoolSize < 0}
|
jaroslav@1890
|
1503 |
* @see #getCorePoolSize
|
jaroslav@1890
|
1504 |
*/
|
jaroslav@1890
|
1505 |
public void setCorePoolSize(int corePoolSize) {
|
jaroslav@1890
|
1506 |
if (corePoolSize < 0)
|
jaroslav@1890
|
1507 |
throw new IllegalArgumentException();
|
jaroslav@1890
|
1508 |
int delta = corePoolSize - this.corePoolSize;
|
jaroslav@1890
|
1509 |
this.corePoolSize = corePoolSize;
|
jaroslav@1890
|
1510 |
if (workerCountOf(ctl.get()) > corePoolSize)
|
jaroslav@1890
|
1511 |
interruptIdleWorkers();
|
jaroslav@1890
|
1512 |
else if (delta > 0) {
|
jaroslav@1890
|
1513 |
// We don't really know how many new threads are "needed".
|
jaroslav@1890
|
1514 |
// As a heuristic, prestart enough new workers (up to new
|
jaroslav@1890
|
1515 |
// core size) to handle the current number of tasks in
|
jaroslav@1890
|
1516 |
// queue, but stop if queue becomes empty while doing so.
|
jaroslav@1890
|
1517 |
int k = Math.min(delta, workQueue.size());
|
jaroslav@1890
|
1518 |
while (k-- > 0 && addWorker(null, true)) {
|
jaroslav@1890
|
1519 |
if (workQueue.isEmpty())
|
jaroslav@1890
|
1520 |
break;
|
jaroslav@1890
|
1521 |
}
|
jaroslav@1890
|
1522 |
}
|
jaroslav@1890
|
1523 |
}
|
jaroslav@1890
|
1524 |
|
jaroslav@1890
|
1525 |
/**
|
jaroslav@1890
|
1526 |
* Returns the core number of threads.
|
jaroslav@1890
|
1527 |
*
|
jaroslav@1890
|
1528 |
* @return the core number of threads
|
jaroslav@1890
|
1529 |
* @see #setCorePoolSize
|
jaroslav@1890
|
1530 |
*/
|
jaroslav@1890
|
1531 |
public int getCorePoolSize() {
|
jaroslav@1890
|
1532 |
return corePoolSize;
|
jaroslav@1890
|
1533 |
}
|
jaroslav@1890
|
1534 |
|
jaroslav@1890
|
1535 |
/**
|
jaroslav@1890
|
1536 |
* Starts a core thread, causing it to idly wait for work. This
|
jaroslav@1890
|
1537 |
* overrides the default policy of starting core threads only when
|
jaroslav@1890
|
1538 |
* new tasks are executed. This method will return {@code false}
|
jaroslav@1890
|
1539 |
* if all core threads have already been started.
|
jaroslav@1890
|
1540 |
*
|
jaroslav@1890
|
1541 |
* @return {@code true} if a thread was started
|
jaroslav@1890
|
1542 |
*/
|
jaroslav@1890
|
1543 |
public boolean prestartCoreThread() {
|
jaroslav@1890
|
1544 |
return workerCountOf(ctl.get()) < corePoolSize &&
|
jaroslav@1890
|
1545 |
addWorker(null, true);
|
jaroslav@1890
|
1546 |
}
|
jaroslav@1890
|
1547 |
|
jaroslav@1890
|
1548 |
/**
|
jaroslav@1890
|
1549 |
* Starts all core threads, causing them to idly wait for work. This
|
jaroslav@1890
|
1550 |
* overrides the default policy of starting core threads only when
|
jaroslav@1890
|
1551 |
* new tasks are executed.
|
jaroslav@1890
|
1552 |
*
|
jaroslav@1890
|
1553 |
* @return the number of threads started
|
jaroslav@1890
|
1554 |
*/
|
jaroslav@1890
|
1555 |
public int prestartAllCoreThreads() {
|
jaroslav@1890
|
1556 |
int n = 0;
|
jaroslav@1890
|
1557 |
while (addWorker(null, true))
|
jaroslav@1890
|
1558 |
++n;
|
jaroslav@1890
|
1559 |
return n;
|
jaroslav@1890
|
1560 |
}
|
jaroslav@1890
|
1561 |
|
jaroslav@1890
|
1562 |
/**
|
jaroslav@1890
|
1563 |
* Returns true if this pool allows core threads to time out and
|
jaroslav@1890
|
1564 |
* terminate if no tasks arrive within the keepAlive time, being
|
jaroslav@1890
|
1565 |
* replaced if needed when new tasks arrive. When true, the same
|
jaroslav@1890
|
1566 |
* keep-alive policy applying to non-core threads applies also to
|
jaroslav@1890
|
1567 |
* core threads. When false (the default), core threads are never
|
jaroslav@1890
|
1568 |
* terminated due to lack of incoming tasks.
|
jaroslav@1890
|
1569 |
*
|
jaroslav@1890
|
1570 |
* @return {@code true} if core threads are allowed to time out,
|
jaroslav@1890
|
1571 |
* else {@code false}
|
jaroslav@1890
|
1572 |
*
|
jaroslav@1890
|
1573 |
* @since 1.6
|
jaroslav@1890
|
1574 |
*/
|
jaroslav@1890
|
1575 |
public boolean allowsCoreThreadTimeOut() {
|
jaroslav@1890
|
1576 |
return allowCoreThreadTimeOut;
|
jaroslav@1890
|
1577 |
}
|
jaroslav@1890
|
1578 |
|
jaroslav@1890
|
1579 |
/**
|
jaroslav@1890
|
1580 |
* Sets the policy governing whether core threads may time out and
|
jaroslav@1890
|
1581 |
* terminate if no tasks arrive within the keep-alive time, being
|
jaroslav@1890
|
1582 |
* replaced if needed when new tasks arrive. When false, core
|
jaroslav@1890
|
1583 |
* threads are never terminated due to lack of incoming
|
jaroslav@1890
|
1584 |
* tasks. When true, the same keep-alive policy applying to
|
jaroslav@1890
|
1585 |
* non-core threads applies also to core threads. To avoid
|
jaroslav@1890
|
1586 |
* continual thread replacement, the keep-alive time must be
|
jaroslav@1890
|
1587 |
* greater than zero when setting {@code true}. This method
|
jaroslav@1890
|
1588 |
* should in general be called before the pool is actively used.
|
jaroslav@1890
|
1589 |
*
|
jaroslav@1890
|
1590 |
* @param value {@code true} if should time out, else {@code false}
|
jaroslav@1890
|
1591 |
* @throws IllegalArgumentException if value is {@code true}
|
jaroslav@1890
|
1592 |
* and the current keep-alive time is not greater than zero
|
jaroslav@1890
|
1593 |
*
|
jaroslav@1890
|
1594 |
* @since 1.6
|
jaroslav@1890
|
1595 |
*/
|
jaroslav@1890
|
1596 |
public void allowCoreThreadTimeOut(boolean value) {
|
jaroslav@1890
|
1597 |
if (value && keepAliveTime <= 0)
|
jaroslav@1890
|
1598 |
throw new IllegalArgumentException("Core threads must have nonzero keep alive times");
|
jaroslav@1890
|
1599 |
if (value != allowCoreThreadTimeOut) {
|
jaroslav@1890
|
1600 |
allowCoreThreadTimeOut = value;
|
jaroslav@1890
|
1601 |
if (value)
|
jaroslav@1890
|
1602 |
interruptIdleWorkers();
|
jaroslav@1890
|
1603 |
}
|
jaroslav@1890
|
1604 |
}
|
jaroslav@1890
|
1605 |
|
jaroslav@1890
|
1606 |
/**
|
jaroslav@1890
|
1607 |
* Sets the maximum allowed number of threads. This overrides any
|
jaroslav@1890
|
1608 |
* value set in the constructor. If the new value is smaller than
|
jaroslav@1890
|
1609 |
* the current value, excess existing threads will be
|
jaroslav@1890
|
1610 |
* terminated when they next become idle.
|
jaroslav@1890
|
1611 |
*
|
jaroslav@1890
|
1612 |
* @param maximumPoolSize the new maximum
|
jaroslav@1890
|
1613 |
* @throws IllegalArgumentException if the new maximum is
|
jaroslav@1890
|
1614 |
* less than or equal to zero, or
|
jaroslav@1890
|
1615 |
* less than the {@linkplain #getCorePoolSize core pool size}
|
jaroslav@1890
|
1616 |
* @see #getMaximumPoolSize
|
jaroslav@1890
|
1617 |
*/
|
jaroslav@1890
|
1618 |
public void setMaximumPoolSize(int maximumPoolSize) {
|
jaroslav@1890
|
1619 |
if (maximumPoolSize <= 0 || maximumPoolSize < corePoolSize)
|
jaroslav@1890
|
1620 |
throw new IllegalArgumentException();
|
jaroslav@1890
|
1621 |
this.maximumPoolSize = maximumPoolSize;
|
jaroslav@1890
|
1622 |
if (workerCountOf(ctl.get()) > maximumPoolSize)
|
jaroslav@1890
|
1623 |
interruptIdleWorkers();
|
jaroslav@1890
|
1624 |
}
|
jaroslav@1890
|
1625 |
|
jaroslav@1890
|
1626 |
/**
|
jaroslav@1890
|
1627 |
* Returns the maximum allowed number of threads.
|
jaroslav@1890
|
1628 |
*
|
jaroslav@1890
|
1629 |
* @return the maximum allowed number of threads
|
jaroslav@1890
|
1630 |
* @see #setMaximumPoolSize
|
jaroslav@1890
|
1631 |
*/
|
jaroslav@1890
|
1632 |
public int getMaximumPoolSize() {
|
jaroslav@1890
|
1633 |
return maximumPoolSize;
|
jaroslav@1890
|
1634 |
}
|
jaroslav@1890
|
1635 |
|
jaroslav@1890
|
1636 |
/**
|
jaroslav@1890
|
1637 |
* Sets the time limit for which threads may remain idle before
|
jaroslav@1890
|
1638 |
* being terminated. If there are more than the core number of
|
jaroslav@1890
|
1639 |
* threads currently in the pool, after waiting this amount of
|
jaroslav@1890
|
1640 |
* time without processing a task, excess threads will be
|
jaroslav@1890
|
1641 |
* terminated. This overrides any value set in the constructor.
|
jaroslav@1890
|
1642 |
*
|
jaroslav@1890
|
1643 |
* @param time the time to wait. A time value of zero will cause
|
jaroslav@1890
|
1644 |
* excess threads to terminate immediately after executing tasks.
|
jaroslav@1890
|
1645 |
* @param unit the time unit of the {@code time} argument
|
jaroslav@1890
|
1646 |
* @throws IllegalArgumentException if {@code time} less than zero or
|
jaroslav@1890
|
1647 |
* if {@code time} is zero and {@code allowsCoreThreadTimeOut}
|
jaroslav@1890
|
1648 |
* @see #getKeepAliveTime
|
jaroslav@1890
|
1649 |
*/
|
jaroslav@1890
|
1650 |
public void setKeepAliveTime(long time, TimeUnit unit) {
|
jaroslav@1890
|
1651 |
if (time < 0)
|
jaroslav@1890
|
1652 |
throw new IllegalArgumentException();
|
jaroslav@1890
|
1653 |
if (time == 0 && allowsCoreThreadTimeOut())
|
jaroslav@1890
|
1654 |
throw new IllegalArgumentException("Core threads must have nonzero keep alive times");
|
jaroslav@1890
|
1655 |
long keepAliveTime = unit.toNanos(time);
|
jaroslav@1890
|
1656 |
long delta = keepAliveTime - this.keepAliveTime;
|
jaroslav@1890
|
1657 |
this.keepAliveTime = keepAliveTime;
|
jaroslav@1890
|
1658 |
if (delta < 0)
|
jaroslav@1890
|
1659 |
interruptIdleWorkers();
|
jaroslav@1890
|
1660 |
}
|
jaroslav@1890
|
1661 |
|
jaroslav@1890
|
1662 |
/**
|
jaroslav@1890
|
1663 |
* Returns the thread keep-alive time, which is the amount of time
|
jaroslav@1890
|
1664 |
* that threads in excess of the core pool size may remain
|
jaroslav@1890
|
1665 |
* idle before being terminated.
|
jaroslav@1890
|
1666 |
*
|
jaroslav@1890
|
1667 |
* @param unit the desired time unit of the result
|
jaroslav@1890
|
1668 |
* @return the time limit
|
jaroslav@1890
|
1669 |
* @see #setKeepAliveTime
|
jaroslav@1890
|
1670 |
*/
|
jaroslav@1890
|
1671 |
public long getKeepAliveTime(TimeUnit unit) {
|
jaroslav@1890
|
1672 |
return unit.convert(keepAliveTime, TimeUnit.NANOSECONDS);
|
jaroslav@1890
|
1673 |
}
|
jaroslav@1890
|
1674 |
|
jaroslav@1890
|
1675 |
/* User-level queue utilities */
|
jaroslav@1890
|
1676 |
|
jaroslav@1890
|
1677 |
/**
|
jaroslav@1890
|
1678 |
* Returns the task queue used by this executor. Access to the
|
jaroslav@1890
|
1679 |
* task queue is intended primarily for debugging and monitoring.
|
jaroslav@1890
|
1680 |
* This queue may be in active use. Retrieving the task queue
|
jaroslav@1890
|
1681 |
* does not prevent queued tasks from executing.
|
jaroslav@1890
|
1682 |
*
|
jaroslav@1890
|
1683 |
* @return the task queue
|
jaroslav@1890
|
1684 |
*/
|
jaroslav@1890
|
1685 |
public BlockingQueue<Runnable> getQueue() {
|
jaroslav@1890
|
1686 |
return workQueue;
|
jaroslav@1890
|
1687 |
}
|
jaroslav@1890
|
1688 |
|
jaroslav@1890
|
1689 |
/**
|
jaroslav@1890
|
1690 |
* Removes this task from the executor's internal queue if it is
|
jaroslav@1890
|
1691 |
* present, thus causing it not to be run if it has not already
|
jaroslav@1890
|
1692 |
* started.
|
jaroslav@1890
|
1693 |
*
|
jaroslav@1890
|
1694 |
* <p> This method may be useful as one part of a cancellation
|
jaroslav@1890
|
1695 |
* scheme. It may fail to remove tasks that have been converted
|
jaroslav@1890
|
1696 |
* into other forms before being placed on the internal queue. For
|
jaroslav@1890
|
1697 |
* example, a task entered using {@code submit} might be
|
jaroslav@1890
|
1698 |
* converted into a form that maintains {@code Future} status.
|
jaroslav@1890
|
1699 |
* However, in such cases, method {@link #purge} may be used to
|
jaroslav@1890
|
1700 |
* remove those Futures that have been cancelled.
|
jaroslav@1890
|
1701 |
*
|
jaroslav@1890
|
1702 |
* @param task the task to remove
|
jaroslav@1890
|
1703 |
* @return true if the task was removed
|
jaroslav@1890
|
1704 |
*/
|
jaroslav@1890
|
1705 |
public boolean remove(Runnable task) {
|
jaroslav@1890
|
1706 |
boolean removed = workQueue.remove(task);
|
jaroslav@1890
|
1707 |
tryTerminate(); // In case SHUTDOWN and now empty
|
jaroslav@1890
|
1708 |
return removed;
|
jaroslav@1890
|
1709 |
}
|
jaroslav@1890
|
1710 |
|
jaroslav@1890
|
1711 |
/**
|
jaroslav@1890
|
1712 |
* Tries to remove from the work queue all {@link Future}
|
jaroslav@1890
|
1713 |
* tasks that have been cancelled. This method can be useful as a
|
jaroslav@1890
|
1714 |
* storage reclamation operation, that has no other impact on
|
jaroslav@1890
|
1715 |
* functionality. Cancelled tasks are never executed, but may
|
jaroslav@1890
|
1716 |
* accumulate in work queues until worker threads can actively
|
jaroslav@1890
|
1717 |
* remove them. Invoking this method instead tries to remove them now.
|
jaroslav@1890
|
1718 |
* However, this method may fail to remove tasks in
|
jaroslav@1890
|
1719 |
* the presence of interference by other threads.
|
jaroslav@1890
|
1720 |
*/
|
jaroslav@1890
|
1721 |
public void purge() {
|
jaroslav@1890
|
1722 |
final BlockingQueue<Runnable> q = workQueue;
|
jaroslav@1890
|
1723 |
try {
|
jaroslav@1890
|
1724 |
Iterator<Runnable> it = q.iterator();
|
jaroslav@1890
|
1725 |
while (it.hasNext()) {
|
jaroslav@1890
|
1726 |
Runnable r = it.next();
|
jaroslav@1890
|
1727 |
if (r instanceof Future<?> && ((Future<?>)r).isCancelled())
|
jaroslav@1890
|
1728 |
it.remove();
|
jaroslav@1890
|
1729 |
}
|
jaroslav@1890
|
1730 |
} catch (ConcurrentModificationException fallThrough) {
|
jaroslav@1890
|
1731 |
// Take slow path if we encounter interference during traversal.
|
jaroslav@1890
|
1732 |
// Make copy for traversal and call remove for cancelled entries.
|
jaroslav@1890
|
1733 |
// The slow path is more likely to be O(N*N).
|
jaroslav@1890
|
1734 |
for (Object r : q.toArray())
|
jaroslav@1890
|
1735 |
if (r instanceof Future<?> && ((Future<?>)r).isCancelled())
|
jaroslav@1890
|
1736 |
q.remove(r);
|
jaroslav@1890
|
1737 |
}
|
jaroslav@1890
|
1738 |
|
jaroslav@1890
|
1739 |
tryTerminate(); // In case SHUTDOWN and now empty
|
jaroslav@1890
|
1740 |
}
|
jaroslav@1890
|
1741 |
|
jaroslav@1890
|
1742 |
/* Statistics */
|
jaroslav@1890
|
1743 |
|
jaroslav@1890
|
1744 |
/**
|
jaroslav@1890
|
1745 |
* Returns the current number of threads in the pool.
|
jaroslav@1890
|
1746 |
*
|
jaroslav@1890
|
1747 |
* @return the number of threads
|
jaroslav@1890
|
1748 |
*/
|
jaroslav@1890
|
1749 |
public int getPoolSize() {
|
jaroslav@1890
|
1750 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
1751 |
mainLock.lock();
|
jaroslav@1890
|
1752 |
try {
|
jaroslav@1890
|
1753 |
// Remove rare and surprising possibility of
|
jaroslav@1890
|
1754 |
// isTerminated() && getPoolSize() > 0
|
jaroslav@1890
|
1755 |
return runStateAtLeast(ctl.get(), TIDYING) ? 0
|
jaroslav@1890
|
1756 |
: workers.size();
|
jaroslav@1890
|
1757 |
} finally {
|
jaroslav@1890
|
1758 |
mainLock.unlock();
|
jaroslav@1890
|
1759 |
}
|
jaroslav@1890
|
1760 |
}
|
jaroslav@1890
|
1761 |
|
jaroslav@1890
|
1762 |
/**
|
jaroslav@1890
|
1763 |
* Returns the approximate number of threads that are actively
|
jaroslav@1890
|
1764 |
* executing tasks.
|
jaroslav@1890
|
1765 |
*
|
jaroslav@1890
|
1766 |
* @return the number of threads
|
jaroslav@1890
|
1767 |
*/
|
jaroslav@1890
|
1768 |
public int getActiveCount() {
|
jaroslav@1890
|
1769 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
1770 |
mainLock.lock();
|
jaroslav@1890
|
1771 |
try {
|
jaroslav@1890
|
1772 |
int n = 0;
|
jaroslav@1890
|
1773 |
for (Worker w : workers)
|
jaroslav@1890
|
1774 |
if (w.isLocked())
|
jaroslav@1890
|
1775 |
++n;
|
jaroslav@1890
|
1776 |
return n;
|
jaroslav@1890
|
1777 |
} finally {
|
jaroslav@1890
|
1778 |
mainLock.unlock();
|
jaroslav@1890
|
1779 |
}
|
jaroslav@1890
|
1780 |
}
|
jaroslav@1890
|
1781 |
|
jaroslav@1890
|
1782 |
/**
|
jaroslav@1890
|
1783 |
* Returns the largest number of threads that have ever
|
jaroslav@1890
|
1784 |
* simultaneously been in the pool.
|
jaroslav@1890
|
1785 |
*
|
jaroslav@1890
|
1786 |
* @return the number of threads
|
jaroslav@1890
|
1787 |
*/
|
jaroslav@1890
|
1788 |
public int getLargestPoolSize() {
|
jaroslav@1890
|
1789 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
1790 |
mainLock.lock();
|
jaroslav@1890
|
1791 |
try {
|
jaroslav@1890
|
1792 |
return largestPoolSize;
|
jaroslav@1890
|
1793 |
} finally {
|
jaroslav@1890
|
1794 |
mainLock.unlock();
|
jaroslav@1890
|
1795 |
}
|
jaroslav@1890
|
1796 |
}
|
jaroslav@1890
|
1797 |
|
jaroslav@1890
|
1798 |
/**
|
jaroslav@1890
|
1799 |
* Returns the approximate total number of tasks that have ever been
|
jaroslav@1890
|
1800 |
* scheduled for execution. Because the states of tasks and
|
jaroslav@1890
|
1801 |
* threads may change dynamically during computation, the returned
|
jaroslav@1890
|
1802 |
* value is only an approximation.
|
jaroslav@1890
|
1803 |
*
|
jaroslav@1890
|
1804 |
* @return the number of tasks
|
jaroslav@1890
|
1805 |
*/
|
jaroslav@1890
|
1806 |
public long getTaskCount() {
|
jaroslav@1890
|
1807 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
1808 |
mainLock.lock();
|
jaroslav@1890
|
1809 |
try {
|
jaroslav@1890
|
1810 |
long n = completedTaskCount;
|
jaroslav@1890
|
1811 |
for (Worker w : workers) {
|
jaroslav@1890
|
1812 |
n += w.completedTasks;
|
jaroslav@1890
|
1813 |
if (w.isLocked())
|
jaroslav@1890
|
1814 |
++n;
|
jaroslav@1890
|
1815 |
}
|
jaroslav@1890
|
1816 |
return n + workQueue.size();
|
jaroslav@1890
|
1817 |
} finally {
|
jaroslav@1890
|
1818 |
mainLock.unlock();
|
jaroslav@1890
|
1819 |
}
|
jaroslav@1890
|
1820 |
}
|
jaroslav@1890
|
1821 |
|
jaroslav@1890
|
1822 |
/**
|
jaroslav@1890
|
1823 |
* Returns the approximate total number of tasks that have
|
jaroslav@1890
|
1824 |
* completed execution. Because the states of tasks and threads
|
jaroslav@1890
|
1825 |
* may change dynamically during computation, the returned value
|
jaroslav@1890
|
1826 |
* is only an approximation, but one that does not ever decrease
|
jaroslav@1890
|
1827 |
* across successive calls.
|
jaroslav@1890
|
1828 |
*
|
jaroslav@1890
|
1829 |
* @return the number of tasks
|
jaroslav@1890
|
1830 |
*/
|
jaroslav@1890
|
1831 |
public long getCompletedTaskCount() {
|
jaroslav@1890
|
1832 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
1833 |
mainLock.lock();
|
jaroslav@1890
|
1834 |
try {
|
jaroslav@1890
|
1835 |
long n = completedTaskCount;
|
jaroslav@1890
|
1836 |
for (Worker w : workers)
|
jaroslav@1890
|
1837 |
n += w.completedTasks;
|
jaroslav@1890
|
1838 |
return n;
|
jaroslav@1890
|
1839 |
} finally {
|
jaroslav@1890
|
1840 |
mainLock.unlock();
|
jaroslav@1890
|
1841 |
}
|
jaroslav@1890
|
1842 |
}
|
jaroslav@1890
|
1843 |
|
jaroslav@1890
|
1844 |
/**
|
jaroslav@1890
|
1845 |
* Returns a string identifying this pool, as well as its state,
|
jaroslav@1890
|
1846 |
* including indications of run state and estimated worker and
|
jaroslav@1890
|
1847 |
* task counts.
|
jaroslav@1890
|
1848 |
*
|
jaroslav@1890
|
1849 |
* @return a string identifying this pool, as well as its state
|
jaroslav@1890
|
1850 |
*/
|
jaroslav@1890
|
1851 |
public String toString() {
|
jaroslav@1890
|
1852 |
long ncompleted;
|
jaroslav@1890
|
1853 |
int nworkers, nactive;
|
jaroslav@1890
|
1854 |
final ReentrantLock mainLock = this.mainLock;
|
jaroslav@1890
|
1855 |
mainLock.lock();
|
jaroslav@1890
|
1856 |
try {
|
jaroslav@1890
|
1857 |
ncompleted = completedTaskCount;
|
jaroslav@1890
|
1858 |
nactive = 0;
|
jaroslav@1890
|
1859 |
nworkers = workers.size();
|
jaroslav@1890
|
1860 |
for (Worker w : workers) {
|
jaroslav@1890
|
1861 |
ncompleted += w.completedTasks;
|
jaroslav@1890
|
1862 |
if (w.isLocked())
|
jaroslav@1890
|
1863 |
++nactive;
|
jaroslav@1890
|
1864 |
}
|
jaroslav@1890
|
1865 |
} finally {
|
jaroslav@1890
|
1866 |
mainLock.unlock();
|
jaroslav@1890
|
1867 |
}
|
jaroslav@1890
|
1868 |
int c = ctl.get();
|
jaroslav@1890
|
1869 |
String rs = (runStateLessThan(c, SHUTDOWN) ? "Running" :
|
jaroslav@1890
|
1870 |
(runStateAtLeast(c, TERMINATED) ? "Terminated" :
|
jaroslav@1890
|
1871 |
"Shutting down"));
|
jaroslav@1890
|
1872 |
return super.toString() +
|
jaroslav@1890
|
1873 |
"[" + rs +
|
jaroslav@1890
|
1874 |
", pool size = " + nworkers +
|
jaroslav@1890
|
1875 |
", active threads = " + nactive +
|
jaroslav@1890
|
1876 |
", queued tasks = " + workQueue.size() +
|
jaroslav@1890
|
1877 |
", completed tasks = " + ncompleted +
|
jaroslav@1890
|
1878 |
"]";
|
jaroslav@1890
|
1879 |
}
|
jaroslav@1890
|
1880 |
|
jaroslav@1890
|
1881 |
/* Extension hooks */
|
jaroslav@1890
|
1882 |
|
jaroslav@1890
|
1883 |
/**
|
jaroslav@1890
|
1884 |
* Method invoked prior to executing the given Runnable in the
|
jaroslav@1890
|
1885 |
* given thread. This method is invoked by thread {@code t} that
|
jaroslav@1890
|
1886 |
* will execute task {@code r}, and may be used to re-initialize
|
jaroslav@1890
|
1887 |
* ThreadLocals, or to perform logging.
|
jaroslav@1890
|
1888 |
*
|
jaroslav@1890
|
1889 |
* <p>This implementation does nothing, but may be customized in
|
jaroslav@1890
|
1890 |
* subclasses. Note: To properly nest multiple overridings, subclasses
|
jaroslav@1890
|
1891 |
* should generally invoke {@code super.beforeExecute} at the end of
|
jaroslav@1890
|
1892 |
* this method.
|
jaroslav@1890
|
1893 |
*
|
jaroslav@1890
|
1894 |
* @param t the thread that will run task {@code r}
|
jaroslav@1890
|
1895 |
* @param r the task that will be executed
|
jaroslav@1890
|
1896 |
*/
|
jaroslav@1890
|
1897 |
protected void beforeExecute(Thread t, Runnable r) { }
|
jaroslav@1890
|
1898 |
|
jaroslav@1890
|
1899 |
/**
|
jaroslav@1890
|
1900 |
* Method invoked upon completion of execution of the given Runnable.
|
jaroslav@1890
|
1901 |
* This method is invoked by the thread that executed the task. If
|
jaroslav@1890
|
1902 |
* non-null, the Throwable is the uncaught {@code RuntimeException}
|
jaroslav@1890
|
1903 |
* or {@code Error} that caused execution to terminate abruptly.
|
jaroslav@1890
|
1904 |
*
|
jaroslav@1890
|
1905 |
* <p>This implementation does nothing, but may be customized in
|
jaroslav@1890
|
1906 |
* subclasses. Note: To properly nest multiple overridings, subclasses
|
jaroslav@1890
|
1907 |
* should generally invoke {@code super.afterExecute} at the
|
jaroslav@1890
|
1908 |
* beginning of this method.
|
jaroslav@1890
|
1909 |
*
|
jaroslav@1890
|
1910 |
* <p><b>Note:</b> When actions are enclosed in tasks (such as
|
jaroslav@1890
|
1911 |
* {@link FutureTask}) either explicitly or via methods such as
|
jaroslav@1890
|
1912 |
* {@code submit}, these task objects catch and maintain
|
jaroslav@1890
|
1913 |
* computational exceptions, and so they do not cause abrupt
|
jaroslav@1890
|
1914 |
* termination, and the internal exceptions are <em>not</em>
|
jaroslav@1890
|
1915 |
* passed to this method. If you would like to trap both kinds of
|
jaroslav@1890
|
1916 |
* failures in this method, you can further probe for such cases,
|
jaroslav@1890
|
1917 |
* as in this sample subclass that prints either the direct cause
|
jaroslav@1890
|
1918 |
* or the underlying exception if a task has been aborted:
|
jaroslav@1890
|
1919 |
*
|
jaroslav@1890
|
1920 |
* <pre> {@code
|
jaroslav@1890
|
1921 |
* class ExtendedExecutor extends ThreadPoolExecutor {
|
jaroslav@1890
|
1922 |
* // ...
|
jaroslav@1890
|
1923 |
* protected void afterExecute(Runnable r, Throwable t) {
|
jaroslav@1890
|
1924 |
* super.afterExecute(r, t);
|
jaroslav@1890
|
1925 |
* if (t == null && r instanceof Future<?>) {
|
jaroslav@1890
|
1926 |
* try {
|
jaroslav@1890
|
1927 |
* Object result = ((Future<?>) r).get();
|
jaroslav@1890
|
1928 |
* } catch (CancellationException ce) {
|
jaroslav@1890
|
1929 |
* t = ce;
|
jaroslav@1890
|
1930 |
* } catch (ExecutionException ee) {
|
jaroslav@1890
|
1931 |
* t = ee.getCause();
|
jaroslav@1890
|
1932 |
* } catch (InterruptedException ie) {
|
jaroslav@1890
|
1933 |
* Thread.currentThread().interrupt(); // ignore/reset
|
jaroslav@1890
|
1934 |
* }
|
jaroslav@1890
|
1935 |
* }
|
jaroslav@1890
|
1936 |
* if (t != null)
|
jaroslav@1890
|
1937 |
* System.out.println(t);
|
jaroslav@1890
|
1938 |
* }
|
jaroslav@1890
|
1939 |
* }}</pre>
|
jaroslav@1890
|
1940 |
*
|
jaroslav@1890
|
1941 |
* @param r the runnable that has completed
|
jaroslav@1890
|
1942 |
* @param t the exception that caused termination, or null if
|
jaroslav@1890
|
1943 |
* execution completed normally
|
jaroslav@1890
|
1944 |
*/
|
jaroslav@1890
|
1945 |
protected void afterExecute(Runnable r, Throwable t) { }
|
jaroslav@1890
|
1946 |
|
jaroslav@1890
|
1947 |
/**
|
jaroslav@1890
|
1948 |
* Method invoked when the Executor has terminated. Default
|
jaroslav@1890
|
1949 |
* implementation does nothing. Note: To properly nest multiple
|
jaroslav@1890
|
1950 |
* overridings, subclasses should generally invoke
|
jaroslav@1890
|
1951 |
* {@code super.terminated} within this method.
|
jaroslav@1890
|
1952 |
*/
|
jaroslav@1890
|
1953 |
protected void terminated() { }
|
jaroslav@1890
|
1954 |
|
jaroslav@1890
|
1955 |
/* Predefined RejectedExecutionHandlers */
|
jaroslav@1890
|
1956 |
|
jaroslav@1890
|
1957 |
/**
|
jaroslav@1890
|
1958 |
* A handler for rejected tasks that runs the rejected task
|
jaroslav@1890
|
1959 |
* directly in the calling thread of the {@code execute} method,
|
jaroslav@1890
|
1960 |
* unless the executor has been shut down, in which case the task
|
jaroslav@1890
|
1961 |
* is discarded.
|
jaroslav@1890
|
1962 |
*/
|
jaroslav@1890
|
1963 |
public static class CallerRunsPolicy implements RejectedExecutionHandler {
|
jaroslav@1890
|
1964 |
/**
|
jaroslav@1890
|
1965 |
* Creates a {@code CallerRunsPolicy}.
|
jaroslav@1890
|
1966 |
*/
|
jaroslav@1890
|
1967 |
public CallerRunsPolicy() { }
|
jaroslav@1890
|
1968 |
|
jaroslav@1890
|
1969 |
/**
|
jaroslav@1890
|
1970 |
* Executes task r in the caller's thread, unless the executor
|
jaroslav@1890
|
1971 |
* has been shut down, in which case the task is discarded.
|
jaroslav@1890
|
1972 |
*
|
jaroslav@1890
|
1973 |
* @param r the runnable task requested to be executed
|
jaroslav@1890
|
1974 |
* @param e the executor attempting to execute this task
|
jaroslav@1890
|
1975 |
*/
|
jaroslav@1890
|
1976 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
|
jaroslav@1890
|
1977 |
if (!e.isShutdown()) {
|
jaroslav@1890
|
1978 |
r.run();
|
jaroslav@1890
|
1979 |
}
|
jaroslav@1890
|
1980 |
}
|
jaroslav@1890
|
1981 |
}
|
jaroslav@1890
|
1982 |
|
jaroslav@1890
|
1983 |
/**
|
jaroslav@1890
|
1984 |
* A handler for rejected tasks that throws a
|
jaroslav@1890
|
1985 |
* {@code RejectedExecutionException}.
|
jaroslav@1890
|
1986 |
*/
|
jaroslav@1890
|
1987 |
public static class AbortPolicy implements RejectedExecutionHandler {
|
jaroslav@1890
|
1988 |
/**
|
jaroslav@1890
|
1989 |
* Creates an {@code AbortPolicy}.
|
jaroslav@1890
|
1990 |
*/
|
jaroslav@1890
|
1991 |
public AbortPolicy() { }
|
jaroslav@1890
|
1992 |
|
jaroslav@1890
|
1993 |
/**
|
jaroslav@1890
|
1994 |
* Always throws RejectedExecutionException.
|
jaroslav@1890
|
1995 |
*
|
jaroslav@1890
|
1996 |
* @param r the runnable task requested to be executed
|
jaroslav@1890
|
1997 |
* @param e the executor attempting to execute this task
|
jaroslav@1890
|
1998 |
* @throws RejectedExecutionException always.
|
jaroslav@1890
|
1999 |
*/
|
jaroslav@1890
|
2000 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
|
jaroslav@1890
|
2001 |
throw new RejectedExecutionException("Task " + r.toString() +
|
jaroslav@1890
|
2002 |
" rejected from " +
|
jaroslav@1890
|
2003 |
e.toString());
|
jaroslav@1890
|
2004 |
}
|
jaroslav@1890
|
2005 |
}
|
jaroslav@1890
|
2006 |
|
jaroslav@1890
|
2007 |
/**
|
jaroslav@1890
|
2008 |
* A handler for rejected tasks that silently discards the
|
jaroslav@1890
|
2009 |
* rejected task.
|
jaroslav@1890
|
2010 |
*/
|
jaroslav@1890
|
2011 |
public static class DiscardPolicy implements RejectedExecutionHandler {
|
jaroslav@1890
|
2012 |
/**
|
jaroslav@1890
|
2013 |
* Creates a {@code DiscardPolicy}.
|
jaroslav@1890
|
2014 |
*/
|
jaroslav@1890
|
2015 |
public DiscardPolicy() { }
|
jaroslav@1890
|
2016 |
|
jaroslav@1890
|
2017 |
/**
|
jaroslav@1890
|
2018 |
* Does nothing, which has the effect of discarding task r.
|
jaroslav@1890
|
2019 |
*
|
jaroslav@1890
|
2020 |
* @param r the runnable task requested to be executed
|
jaroslav@1890
|
2021 |
* @param e the executor attempting to execute this task
|
jaroslav@1890
|
2022 |
*/
|
jaroslav@1890
|
2023 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
|
jaroslav@1890
|
2024 |
}
|
jaroslav@1890
|
2025 |
}
|
jaroslav@1890
|
2026 |
|
jaroslav@1890
|
2027 |
/**
|
jaroslav@1890
|
2028 |
* A handler for rejected tasks that discards the oldest unhandled
|
jaroslav@1890
|
2029 |
* request and then retries {@code execute}, unless the executor
|
jaroslav@1890
|
2030 |
* is shut down, in which case the task is discarded.
|
jaroslav@1890
|
2031 |
*/
|
jaroslav@1890
|
2032 |
public static class DiscardOldestPolicy implements RejectedExecutionHandler {
|
jaroslav@1890
|
2033 |
/**
|
jaroslav@1890
|
2034 |
* Creates a {@code DiscardOldestPolicy} for the given executor.
|
jaroslav@1890
|
2035 |
*/
|
jaroslav@1890
|
2036 |
public DiscardOldestPolicy() { }
|
jaroslav@1890
|
2037 |
|
jaroslav@1890
|
2038 |
/**
|
jaroslav@1890
|
2039 |
* Obtains and ignores the next task that the executor
|
jaroslav@1890
|
2040 |
* would otherwise execute, if one is immediately available,
|
jaroslav@1890
|
2041 |
* and then retries execution of task r, unless the executor
|
jaroslav@1890
|
2042 |
* is shut down, in which case task r is instead discarded.
|
jaroslav@1890
|
2043 |
*
|
jaroslav@1890
|
2044 |
* @param r the runnable task requested to be executed
|
jaroslav@1890
|
2045 |
* @param e the executor attempting to execute this task
|
jaroslav@1890
|
2046 |
*/
|
jaroslav@1890
|
2047 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
|
jaroslav@1890
|
2048 |
if (!e.isShutdown()) {
|
jaroslav@1890
|
2049 |
e.getQueue().poll();
|
jaroslav@1890
|
2050 |
e.execute(r);
|
jaroslav@1890
|
2051 |
}
|
jaroslav@1890
|
2052 |
}
|
jaroslav@1890
|
2053 |
}
|
jaroslav@1890
|
2054 |
}
|