1 |
tim |
1.1 |
/* |
2 |
dl |
1.2 |
* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
dl |
1.47 |
* Expert Group and released to the public domain, as explained at |
4 |
|
|
* http://creativecommons.org/licenses/publicdomain |
5 |
tim |
1.1 |
*/ |
6 |
|
|
|
7 |
|
|
package java.util.concurrent; |
8 |
dl |
1.9 |
import java.util.concurrent.locks.*; |
9 |
dl |
1.2 |
import java.util.*; |
10 |
tim |
1.1 |
|
11 |
|
|
/** |
12 |
dl |
1.17 |
* An {@link ExecutorService} that executes each submitted task using |
13 |
dl |
1.28 |
* one of possibly several pooled threads, normally configured |
14 |
|
|
* using {@link Executors} factory methods. |
15 |
tim |
1.1 |
* |
16 |
dl |
1.17 |
* <p>Thread pools address two different problems: they usually |
17 |
|
|
* provide improved performance when executing large numbers of |
18 |
|
|
* asynchronous tasks, due to reduced per-task invocation overhead, |
19 |
|
|
* and they provide a means of bounding and managing the resources, |
20 |
|
|
* including threads, consumed when executing a collection of tasks. |
21 |
dl |
1.20 |
* Each <tt>ThreadPoolExecutor</tt> also maintains some basic |
22 |
dl |
1.22 |
* statistics, such as the number of completed tasks. |
23 |
dl |
1.17 |
* |
24 |
tim |
1.1 |
* <p>To be useful across a wide range of contexts, this class |
25 |
dl |
1.24 |
* provides many adjustable parameters and extensibility |
26 |
|
|
* hooks. However, programmers are urged to use the more convenient |
27 |
dl |
1.20 |
* {@link Executors} factory methods {@link |
28 |
|
|
* Executors#newCachedThreadPool} (unbounded thread pool, with |
29 |
|
|
* automatic thread reclamation), {@link Executors#newFixedThreadPool} |
30 |
|
|
* (fixed size thread pool) and {@link |
31 |
|
|
* Executors#newSingleThreadExecutor} (single background thread), that |
32 |
dl |
1.22 |
* preconfigure settings for the most common usage |
33 |
|
|
* scenarios. Otherwise, use the following guide when manually |
34 |
dl |
1.24 |
* configuring and tuning this class: |
35 |
dl |
1.17 |
* |
36 |
tim |
1.1 |
* <dl> |
37 |
dl |
1.2 |
* |
38 |
dl |
1.21 |
* <dt>Core and maximum pool sizes</dt> |
39 |
dl |
1.2 |
* |
40 |
dl |
1.19 |
* <dd>A <tt>ThreadPoolExecutor</tt> will automatically adjust the |
41 |
jsr166 |
1.66 |
* pool size |
42 |
dl |
1.21 |
* (see {@link ThreadPoolExecutor#getPoolSize}) |
43 |
jsr166 |
1.66 |
* according to the bounds set by corePoolSize |
44 |
dl |
1.21 |
* (see {@link ThreadPoolExecutor#getCorePoolSize}) |
45 |
|
|
* and |
46 |
|
|
* maximumPoolSize |
47 |
|
|
* (see {@link ThreadPoolExecutor#getMaximumPoolSize}). |
48 |
|
|
* When a new task is submitted in method {@link |
49 |
|
|
* ThreadPoolExecutor#execute}, and fewer than corePoolSize threads |
50 |
|
|
* are running, a new thread is created to handle the request, even if |
51 |
|
|
* other worker threads are idle. If there are more than |
52 |
|
|
* corePoolSize but less than maximumPoolSize threads running, a new |
53 |
|
|
* thread will be created only if the queue is full. By setting |
54 |
|
|
* corePoolSize and maximumPoolSize the same, you create a fixed-size |
55 |
|
|
* thread pool. By setting maximumPoolSize to an essentially unbounded |
56 |
|
|
* value such as <tt>Integer.MAX_VALUE</tt>, you allow the pool to |
57 |
dl |
1.27 |
* accommodate an arbitrary number of concurrent tasks. Most typically, |
58 |
dl |
1.21 |
* core and maximum pool sizes are set only upon construction, but they |
59 |
|
|
* may also be changed dynamically using {@link |
60 |
|
|
* ThreadPoolExecutor#setCorePoolSize} and {@link |
61 |
|
|
* ThreadPoolExecutor#setMaximumPoolSize}. <dd> |
62 |
dl |
1.2 |
* |
63 |
dl |
1.21 |
* <dt> On-demand construction |
64 |
dl |
1.2 |
* |
65 |
dl |
1.21 |
* <dd> By default, even core threads are initially created and |
66 |
dl |
1.69 |
* started only when new tasks arrive, but this can be overridden |
67 |
dl |
1.21 |
* dynamically using method {@link |
68 |
|
|
* ThreadPoolExecutor#prestartCoreThread} or |
69 |
dl |
1.64 |
* {@link ThreadPoolExecutor#prestartAllCoreThreads}. |
70 |
|
|
* You probably want to prestart threads if you construct the |
71 |
|
|
* pool with a non-empty queue. </dd> |
72 |
dl |
1.2 |
* |
73 |
tim |
1.1 |
* <dt>Creating new threads</dt> |
74 |
dl |
1.2 |
* |
75 |
dl |
1.33 |
* <dd>New threads are created using a {@link |
76 |
|
|
* java.util.concurrent.ThreadFactory}. If not otherwise specified, a |
77 |
dl |
1.34 |
* {@link Executors#defaultThreadFactory} is used, that creates threads to all |
78 |
dl |
1.33 |
* be in the same {@link ThreadGroup} and with the same |
79 |
|
|
* <tt>NORM_PRIORITY</tt> priority and non-daemon status. By supplying |
80 |
|
|
* a different ThreadFactory, you can alter the thread's name, thread |
81 |
dl |
1.57 |
* group, priority, daemon status, etc. If a <tt>ThreadFactory</tt> fails to create |
82 |
jsr166 |
1.66 |
* a thread when asked by returning null from <tt>newThread</tt>, |
83 |
dl |
1.57 |
* the executor will continue, but might |
84 |
dl |
1.56 |
* not be able to execute any tasks. </dd> |
85 |
dl |
1.2 |
* |
86 |
dl |
1.21 |
* <dt>Keep-alive times</dt> |
87 |
|
|
* |
88 |
|
|
* <dd>If the pool currently has more than corePoolSize threads, |
89 |
|
|
* excess threads will be terminated if they have been idle for more |
90 |
|
|
* than the keepAliveTime (see {@link |
91 |
|
|
* ThreadPoolExecutor#getKeepAliveTime}). This provides a means of |
92 |
|
|
* reducing resource consumption when the pool is not being actively |
93 |
|
|
* used. If the pool becomes more active later, new threads will be |
94 |
dl |
1.62 |
* constructed. This parameter can also be changed dynamically using |
95 |
|
|
* method {@link ThreadPoolExecutor#setKeepAliveTime}. Using a value |
96 |
|
|
* of <tt>Long.MAX_VALUE</tt> {@link TimeUnit#NANOSECONDS} effectively |
97 |
|
|
* disables idle threads from ever terminating prior to shut down. By |
98 |
|
|
* default, the keep-alive policy applies only when there are more |
99 |
|
|
* than corePoolSizeThreads. But method {@link |
100 |
|
|
* ThreadPoolExecutor#allowCoreThreadTimeOut} can be used to apply |
101 |
dl |
1.64 |
* this time-out policy to core threads as well, so long as |
102 |
|
|
* the keepAliveTime value is non-zero. </dd> |
103 |
dl |
1.21 |
* |
104 |
dl |
1.48 |
* <dt>Queuing</dt> |
105 |
dl |
1.21 |
* |
106 |
|
|
* <dd>Any {@link BlockingQueue} may be used to transfer and hold |
107 |
|
|
* submitted tasks. The use of this queue interacts with pool sizing: |
108 |
dl |
1.2 |
* |
109 |
dl |
1.21 |
* <ul> |
110 |
|
|
* |
111 |
dl |
1.23 |
* <li> If fewer than corePoolSize threads are running, the Executor |
112 |
|
|
* always prefers adding a new thread |
113 |
dl |
1.48 |
* rather than queuing.</li> |
114 |
dl |
1.21 |
* |
115 |
dl |
1.23 |
* <li> If corePoolSize or more threads are running, the Executor |
116 |
|
|
* always prefers queuing a request rather than adding a new |
117 |
|
|
* thread.</li> |
118 |
jsr166 |
1.66 |
* |
119 |
dl |
1.21 |
* <li> If a request cannot be queued, a new thread is created unless |
120 |
|
|
* this would exceed maximumPoolSize, in which case, the task will be |
121 |
|
|
* rejected.</li> |
122 |
|
|
* |
123 |
|
|
* </ul> |
124 |
|
|
* |
125 |
|
|
* There are three general strategies for queuing: |
126 |
|
|
* <ol> |
127 |
|
|
* |
128 |
|
|
* <li> <em> Direct handoffs.</em> A good default choice for a work |
129 |
|
|
* queue is a {@link SynchronousQueue} that hands off tasks to threads |
130 |
|
|
* without otherwise holding them. Here, an attempt to queue a task |
131 |
|
|
* will fail if no threads are immediately available to run it, so a |
132 |
|
|
* new thread will be constructed. This policy avoids lockups when |
133 |
|
|
* handling sets of requests that might have internal dependencies. |
134 |
|
|
* Direct handoffs generally require unbounded maximumPoolSizes to |
135 |
dl |
1.24 |
* avoid rejection of new submitted tasks. This in turn admits the |
136 |
dl |
1.21 |
* possibility of unbounded thread growth when commands continue to |
137 |
|
|
* arrive on average faster than they can be processed. </li> |
138 |
|
|
* |
139 |
|
|
* <li><em> Unbounded queues.</em> Using an unbounded queue (for |
140 |
|
|
* example a {@link LinkedBlockingQueue} without a predefined |
141 |
dl |
1.69 |
* capacity) will cause new tasks to wait in the queue when all |
142 |
dl |
1.22 |
* corePoolSize threads are busy. Thus, no more than corePoolSize |
143 |
|
|
* threads will ever be created. (And the value of the maximumPoolSize |
144 |
|
|
* therefore doesn't have any effect.) This may be appropriate when |
145 |
|
|
* each task is completely independent of others, so tasks cannot |
146 |
|
|
* affect each others execution; for example, in a web page server. |
147 |
|
|
* While this style of queuing can be useful in smoothing out |
148 |
|
|
* transient bursts of requests, it admits the possibility of |
149 |
|
|
* unbounded work queue growth when commands continue to arrive on |
150 |
|
|
* average faster than they can be processed. </li> |
151 |
dl |
1.21 |
* |
152 |
|
|
* <li><em>Bounded queues.</em> A bounded queue (for example, an |
153 |
|
|
* {@link ArrayBlockingQueue}) helps prevent resource exhaustion when |
154 |
|
|
* used with finite maximumPoolSizes, but can be more difficult to |
155 |
|
|
* tune and control. Queue sizes and maximum pool sizes may be traded |
156 |
|
|
* off for each other: Using large queues and small pools minimizes |
157 |
|
|
* CPU usage, OS resources, and context-switching overhead, but can |
158 |
dl |
1.27 |
* lead to artificially low throughput. If tasks frequently block (for |
159 |
dl |
1.21 |
* example if they are I/O bound), a system may be able to schedule |
160 |
|
|
* time for more threads than you otherwise allow. Use of small queues |
161 |
dl |
1.24 |
* generally requires larger pool sizes, which keeps CPUs busier but |
162 |
|
|
* may encounter unacceptable scheduling overhead, which also |
163 |
|
|
* decreases throughput. </li> |
164 |
dl |
1.21 |
* |
165 |
|
|
* </ol> |
166 |
|
|
* |
167 |
|
|
* </dd> |
168 |
|
|
* |
169 |
|
|
* <dt>Rejected tasks</dt> |
170 |
|
|
* |
171 |
|
|
* <dd> New tasks submitted in method {@link |
172 |
|
|
* ThreadPoolExecutor#execute} will be <em>rejected</em> when the |
173 |
|
|
* Executor has been shut down, and also when the Executor uses finite |
174 |
|
|
* bounds for both maximum threads and work queue capacity, and is |
175 |
dl |
1.22 |
* saturated. In either case, the <tt>execute</tt> method invokes the |
176 |
|
|
* {@link RejectedExecutionHandler#rejectedExecution} method of its |
177 |
|
|
* {@link RejectedExecutionHandler}. Four predefined handler policies |
178 |
|
|
* are provided: |
179 |
dl |
1.21 |
* |
180 |
|
|
* <ol> |
181 |
|
|
* |
182 |
|
|
* <li> In the |
183 |
|
|
* default {@link ThreadPoolExecutor.AbortPolicy}, the handler throws a |
184 |
|
|
* runtime {@link RejectedExecutionException} upon rejection. </li> |
185 |
jsr166 |
1.66 |
* |
186 |
dl |
1.21 |
* <li> In {@link |
187 |
|
|
* ThreadPoolExecutor.CallerRunsPolicy}, the thread that invokes |
188 |
|
|
* <tt>execute</tt> itself runs the task. This provides a simple |
189 |
|
|
* feedback control mechanism that will slow down the rate that new |
190 |
|
|
* tasks are submitted. </li> |
191 |
|
|
* |
192 |
|
|
* <li> In {@link ThreadPoolExecutor.DiscardPolicy}, |
193 |
|
|
* a task that cannot be executed is simply dropped. </li> |
194 |
|
|
* |
195 |
|
|
* <li>In {@link |
196 |
|
|
* ThreadPoolExecutor.DiscardOldestPolicy}, if the executor is not |
197 |
|
|
* shut down, the task at the head of the work queue is dropped, and |
198 |
|
|
* then execution is retried (which can fail again, causing this to be |
199 |
|
|
* repeated.) </li> |
200 |
|
|
* |
201 |
|
|
* </ol> |
202 |
|
|
* |
203 |
|
|
* It is possible to define and use other kinds of {@link |
204 |
|
|
* RejectedExecutionHandler} classes. Doing so requires some care |
205 |
|
|
* especially when policies are designed to work only under particular |
206 |
dl |
1.48 |
* capacity or queuing policies. </dd> |
207 |
dl |
1.21 |
* |
208 |
|
|
* <dt>Hook methods</dt> |
209 |
|
|
* |
210 |
dl |
1.23 |
* <dd>This class provides <tt>protected</tt> overridable {@link |
211 |
dl |
1.21 |
* ThreadPoolExecutor#beforeExecute} and {@link |
212 |
|
|
* ThreadPoolExecutor#afterExecute} methods that are called before and |
213 |
dl |
1.19 |
* after execution of each task. These can be used to manipulate the |
214 |
dl |
1.59 |
* execution environment; for example, reinitializing ThreadLocals, |
215 |
dl |
1.21 |
* gathering statistics, or adding log entries. Additionally, method |
216 |
|
|
* {@link ThreadPoolExecutor#terminated} can be overridden to perform |
217 |
|
|
* any special processing that needs to be done once the Executor has |
218 |
jsr166 |
1.66 |
* fully terminated. |
219 |
dl |
1.57 |
* |
220 |
jsr166 |
1.66 |
* <p>If hook or callback methods throw |
221 |
dl |
1.57 |
* exceptions, internal worker threads may in turn fail and |
222 |
jsr166 |
1.66 |
* abruptly terminate.</dd> |
223 |
dl |
1.2 |
* |
224 |
dl |
1.21 |
* <dt>Queue maintenance</dt> |
225 |
dl |
1.2 |
* |
226 |
dl |
1.24 |
* <dd> Method {@link ThreadPoolExecutor#getQueue} allows access to |
227 |
|
|
* the work queue for purposes of monitoring and debugging. Use of |
228 |
|
|
* this method for any other purpose is strongly discouraged. Two |
229 |
|
|
* supplied methods, {@link ThreadPoolExecutor#remove} and {@link |
230 |
|
|
* ThreadPoolExecutor#purge} are available to assist in storage |
231 |
|
|
* reclamation when large numbers of queued tasks become |
232 |
jsr166 |
1.80 |
* cancelled.</dd> |
233 |
dl |
1.79 |
* |
234 |
|
|
* <dt>Finalization</dt> |
235 |
|
|
* |
236 |
|
|
* <dd> A pool that is no longer referenced in a program <em>AND</em> |
237 |
|
|
* has no remaining threads will be <tt>shutdown</tt> |
238 |
|
|
* automatically. If you would like to ensure that unreferenced pools |
239 |
|
|
* are reclaimed even if users forget to call {@link |
240 |
|
|
* ThreadPoolExecutor#shutdown}, then you must arrange that unused |
241 |
|
|
* threads eventually die, by setting appropriate keep-alive times, |
242 |
|
|
* using a lower bound of zero core threads and/or setting {@link |
243 |
|
|
* ThreadPoolExecutor#allowCoreThreadTimeOut}. </dd> </dl> |
244 |
tim |
1.1 |
* |
245 |
dl |
1.43 |
* <p> <b>Extension example</b>. Most extensions of this class |
246 |
|
|
* override one or more of the protected hook methods. For example, |
247 |
|
|
* here is a subclass that adds a simple pause/resume feature: |
248 |
|
|
* |
249 |
|
|
* <pre> |
250 |
|
|
* class PausableThreadPoolExecutor extends ThreadPoolExecutor { |
251 |
|
|
* private boolean isPaused; |
252 |
|
|
* private ReentrantLock pauseLock = new ReentrantLock(); |
253 |
|
|
* private Condition unpaused = pauseLock.newCondition(); |
254 |
|
|
* |
255 |
|
|
* public PausableThreadPoolExecutor(...) { super(...); } |
256 |
jsr166 |
1.66 |
* |
257 |
dl |
1.43 |
* protected void beforeExecute(Thread t, Runnable r) { |
258 |
|
|
* super.beforeExecute(t, r); |
259 |
|
|
* pauseLock.lock(); |
260 |
|
|
* try { |
261 |
|
|
* while (isPaused) unpaused.await(); |
262 |
jsr166 |
1.66 |
* } catch (InterruptedException ie) { |
263 |
dl |
1.53 |
* t.interrupt(); |
264 |
dl |
1.43 |
* } finally { |
265 |
dl |
1.53 |
* pauseLock.unlock(); |
266 |
dl |
1.43 |
* } |
267 |
|
|
* } |
268 |
jsr166 |
1.66 |
* |
269 |
dl |
1.43 |
* public void pause() { |
270 |
|
|
* pauseLock.lock(); |
271 |
|
|
* try { |
272 |
|
|
* isPaused = true; |
273 |
|
|
* } finally { |
274 |
dl |
1.53 |
* pauseLock.unlock(); |
275 |
dl |
1.43 |
* } |
276 |
|
|
* } |
277 |
jsr166 |
1.66 |
* |
278 |
dl |
1.43 |
* public void resume() { |
279 |
|
|
* pauseLock.lock(); |
280 |
|
|
* try { |
281 |
|
|
* isPaused = false; |
282 |
|
|
* unpaused.signalAll(); |
283 |
|
|
* } finally { |
284 |
dl |
1.53 |
* pauseLock.unlock(); |
285 |
dl |
1.43 |
* } |
286 |
|
|
* } |
287 |
|
|
* } |
288 |
|
|
* </pre> |
289 |
tim |
1.1 |
* @since 1.5 |
290 |
dl |
1.8 |
* @author Doug Lea |
291 |
tim |
1.1 |
*/ |
292 |
tim |
1.38 |
public class ThreadPoolExecutor extends AbstractExecutorService { |
293 |
dl |
1.2 |
/** |
294 |
tim |
1.41 |
* Only used to force toArray() to produce a Runnable[]. |
295 |
|
|
*/ |
296 |
|
|
private static final Runnable[] EMPTY_RUNNABLE_ARRAY = new Runnable[0]; |
297 |
|
|
|
298 |
|
|
/** |
299 |
dl |
1.43 |
* Permission for checking shutdown |
300 |
|
|
*/ |
301 |
|
|
private static final RuntimePermission shutdownPerm = |
302 |
|
|
new RuntimePermission("modifyThread"); |
303 |
|
|
|
304 |
|
|
/** |
305 |
dl |
1.2 |
* Queue used for holding tasks and handing off to worker threads. |
306 |
tim |
1.10 |
*/ |
307 |
dl |
1.2 |
private final BlockingQueue<Runnable> workQueue; |
308 |
|
|
|
309 |
|
|
/** |
310 |
|
|
* Lock held on updates to poolSize, corePoolSize, maximumPoolSize, and |
311 |
|
|
* workers set. |
312 |
tim |
1.10 |
*/ |
313 |
dl |
1.2 |
private final ReentrantLock mainLock = new ReentrantLock(); |
314 |
|
|
|
315 |
|
|
/** |
316 |
|
|
* Wait condition to support awaitTermination |
317 |
tim |
1.10 |
*/ |
318 |
dl |
1.46 |
private final Condition termination = mainLock.newCondition(); |
319 |
dl |
1.2 |
|
320 |
|
|
/** |
321 |
|
|
* Set containing all worker threads in pool. |
322 |
tim |
1.10 |
*/ |
323 |
dl |
1.17 |
private final HashSet<Worker> workers = new HashSet<Worker>(); |
324 |
dl |
1.2 |
|
325 |
|
|
/** |
326 |
dl |
1.35 |
* Timeout in nanoseconds for idle threads waiting for work. |
327 |
dl |
1.2 |
* Threads use this timeout only when there are more than |
328 |
|
|
* corePoolSize present. Otherwise they wait forever for new work. |
329 |
tim |
1.10 |
*/ |
330 |
dl |
1.2 |
private volatile long keepAliveTime; |
331 |
|
|
|
332 |
|
|
/** |
333 |
dl |
1.62 |
* If false (default) core threads stay alive even when idle. |
334 |
|
|
* If true, core threads use keepAliveTime to time out waiting for work. |
335 |
|
|
*/ |
336 |
|
|
private boolean allowCoreThreadTimeOut; |
337 |
|
|
|
338 |
|
|
/** |
339 |
dl |
1.2 |
* Core pool size, updated only while holding mainLock, |
340 |
|
|
* but volatile to allow concurrent readability even |
341 |
|
|
* during updates. |
342 |
tim |
1.10 |
*/ |
343 |
dl |
1.2 |
private volatile int corePoolSize; |
344 |
|
|
|
345 |
|
|
/** |
346 |
|
|
* Maximum pool size, updated only while holding mainLock |
347 |
|
|
* but volatile to allow concurrent readability even |
348 |
|
|
* during updates. |
349 |
tim |
1.10 |
*/ |
350 |
dl |
1.2 |
private volatile int maximumPoolSize; |
351 |
|
|
|
352 |
|
|
/** |
353 |
|
|
* Current pool size, updated only while holding mainLock |
354 |
|
|
* but volatile to allow concurrent readability even |
355 |
|
|
* during updates. |
356 |
tim |
1.10 |
*/ |
357 |
dl |
1.2 |
private volatile int poolSize; |
358 |
|
|
|
359 |
|
|
/** |
360 |
dl |
1.16 |
* Lifecycle state |
361 |
tim |
1.10 |
*/ |
362 |
dl |
1.52 |
volatile int runState; |
363 |
dl |
1.2 |
|
364 |
dl |
1.16 |
// Special values for runState |
365 |
dl |
1.8 |
/** Normal, not-shutdown mode */ |
366 |
dl |
1.52 |
static final int RUNNING = 0; |
367 |
dl |
1.8 |
/** Controlled shutdown mode */ |
368 |
dl |
1.52 |
static final int SHUTDOWN = 1; |
369 |
dl |
1.16 |
/** Immediate shutdown mode */ |
370 |
dl |
1.52 |
static final int STOP = 2; |
371 |
dl |
1.16 |
/** Final state */ |
372 |
dl |
1.52 |
static final int TERMINATED = 3; |
373 |
dl |
1.2 |
|
374 |
|
|
/** |
375 |
|
|
* Handler called when saturated or shutdown in execute. |
376 |
tim |
1.10 |
*/ |
377 |
dl |
1.33 |
private volatile RejectedExecutionHandler handler; |
378 |
dl |
1.2 |
|
379 |
|
|
/** |
380 |
|
|
* Factory for new threads. |
381 |
tim |
1.10 |
*/ |
382 |
dl |
1.33 |
private volatile ThreadFactory threadFactory; |
383 |
dl |
1.2 |
|
384 |
|
|
/** |
385 |
|
|
* Tracks largest attained pool size. |
386 |
tim |
1.10 |
*/ |
387 |
dl |
1.2 |
private int largestPoolSize; |
388 |
|
|
|
389 |
|
|
/** |
390 |
|
|
* Counter for completed tasks. Updated only on termination of |
391 |
|
|
* worker threads. |
392 |
tim |
1.10 |
*/ |
393 |
dl |
1.2 |
private long completedTaskCount; |
394 |
jsr166 |
1.66 |
|
395 |
dl |
1.8 |
/** |
396 |
dl |
1.35 |
* The default rejected execution handler |
397 |
dl |
1.8 |
*/ |
398 |
tim |
1.10 |
private static final RejectedExecutionHandler defaultHandler = |
399 |
dl |
1.2 |
new AbortPolicy(); |
400 |
|
|
|
401 |
|
|
/** |
402 |
jsr166 |
1.66 |
* Invokes the rejected execution handler for the given command. |
403 |
dl |
1.13 |
*/ |
404 |
|
|
void reject(Runnable command) { |
405 |
|
|
handler.rejectedExecution(command, this); |
406 |
|
|
} |
407 |
|
|
|
408 |
dl |
1.33 |
/** |
409 |
jsr166 |
1.66 |
* Creates and returns a new thread running firstTask as its first |
410 |
|
|
* task. Call only while holding mainLock. |
411 |
dl |
1.8 |
* @param firstTask the task the new thread should run first (or |
412 |
|
|
* null if none) |
413 |
dl |
1.56 |
* @return the new thread, or null if threadFactory fails to create thread |
414 |
dl |
1.2 |
*/ |
415 |
|
|
private Thread addThread(Runnable firstTask) { |
416 |
|
|
Worker w = new Worker(firstTask); |
417 |
dl |
1.57 |
Thread t = threadFactory.newThread(w); |
418 |
dl |
1.56 |
if (t != null) { |
419 |
|
|
w.thread = t; |
420 |
|
|
workers.add(w); |
421 |
|
|
int nt = ++poolSize; |
422 |
|
|
if (nt > largestPoolSize) |
423 |
|
|
largestPoolSize = nt; |
424 |
|
|
} |
425 |
dl |
1.2 |
return t; |
426 |
|
|
} |
427 |
dl |
1.15 |
|
428 |
dl |
1.2 |
/** |
429 |
jsr166 |
1.66 |
* Creates and starts a new thread running firstTask as its first |
430 |
dl |
1.50 |
* task, only if fewer than corePoolSize threads are running. |
431 |
dl |
1.8 |
* @param firstTask the task the new thread should run first (or |
432 |
|
|
* null if none) |
433 |
dl |
1.2 |
* @return true if successful. |
434 |
|
|
*/ |
435 |
dl |
1.16 |
private boolean addIfUnderCorePoolSize(Runnable firstTask) { |
436 |
dl |
1.2 |
Thread t = null; |
437 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
438 |
dl |
1.2 |
mainLock.lock(); |
439 |
|
|
try { |
440 |
tim |
1.10 |
if (poolSize < corePoolSize) |
441 |
dl |
1.8 |
t = addThread(firstTask); |
442 |
tim |
1.14 |
} finally { |
443 |
dl |
1.2 |
mainLock.unlock(); |
444 |
|
|
} |
445 |
|
|
if (t == null) |
446 |
|
|
return false; |
447 |
|
|
t.start(); |
448 |
|
|
return true; |
449 |
|
|
} |
450 |
|
|
|
451 |
|
|
/** |
452 |
jsr166 |
1.66 |
* Creates and starts a new thread only if fewer than maximumPoolSize |
453 |
dl |
1.2 |
* threads are running. The new thread runs as its first task the |
454 |
|
|
* next task in queue, or if there is none, the given task. |
455 |
dl |
1.8 |
* @param firstTask the task the new thread should run first (or |
456 |
|
|
* null if none) |
457 |
dl |
1.74 |
* @return 0 if a new thread cannot be created, a positive number |
458 |
|
|
* if firstTask will be run in a new thread, or a negative number |
459 |
|
|
* if a new thread was created but is running some other task, in |
460 |
|
|
* which case the caller must try some other way to run firstTask |
461 |
|
|
* (perhaps by calling this method again). |
462 |
dl |
1.2 |
*/ |
463 |
dl |
1.74 |
private int addIfUnderMaximumPoolSize(Runnable firstTask) { |
464 |
dl |
1.2 |
Thread t = null; |
465 |
dl |
1.74 |
int status = 0; |
466 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
467 |
dl |
1.2 |
mainLock.lock(); |
468 |
|
|
try { |
469 |
|
|
if (poolSize < maximumPoolSize) { |
470 |
dl |
1.74 |
Runnable next = workQueue.poll(); |
471 |
|
|
if (next == null) { |
472 |
dl |
1.8 |
next = firstTask; |
473 |
dl |
1.74 |
status = 1; |
474 |
|
|
} else |
475 |
|
|
status = -1; |
476 |
dl |
1.2 |
t = addThread(next); |
477 |
|
|
} |
478 |
tim |
1.14 |
} finally { |
479 |
dl |
1.2 |
mainLock.unlock(); |
480 |
|
|
} |
481 |
|
|
if (t == null) |
482 |
dl |
1.74 |
return 0; |
483 |
dl |
1.2 |
t.start(); |
484 |
dl |
1.74 |
return status; |
485 |
dl |
1.2 |
} |
486 |
|
|
|
487 |
|
|
|
488 |
|
|
/** |
489 |
jsr166 |
1.66 |
* Gets the next task for a worker thread to run. |
490 |
dl |
1.8 |
* @return the task |
491 |
dl |
1.2 |
*/ |
492 |
dl |
1.63 |
Runnable getTask() { |
493 |
dl |
1.2 |
for (;;) { |
494 |
dl |
1.63 |
try { |
495 |
jsr166 |
1.73 |
switch (runState) { |
496 |
dl |
1.63 |
case RUNNING: { |
497 |
|
|
// untimed wait if core and not allowing core timeout |
498 |
|
|
if (poolSize <= corePoolSize && !allowCoreThreadTimeOut) |
499 |
|
|
return workQueue.take(); |
500 |
jsr166 |
1.66 |
|
501 |
dl |
1.63 |
long timeout = keepAliveTime; |
502 |
|
|
if (timeout <= 0) // die immediately for 0 timeout |
503 |
|
|
return null; |
504 |
jsr166 |
1.70 |
Runnable r = workQueue.poll(timeout, TimeUnit.NANOSECONDS); |
505 |
dl |
1.63 |
if (r != null) |
506 |
|
|
return r; |
507 |
jsr166 |
1.66 |
if (poolSize > corePoolSize || allowCoreThreadTimeOut) |
508 |
dl |
1.63 |
return null; // timed out |
509 |
|
|
// Else, after timeout, the pool shrank. Retry |
510 |
|
|
break; |
511 |
|
|
} |
512 |
jsr166 |
1.66 |
|
513 |
dl |
1.63 |
case SHUTDOWN: { |
514 |
jsr166 |
1.66 |
// Help drain queue |
515 |
dl |
1.63 |
Runnable r = workQueue.poll(); |
516 |
|
|
if (r != null) |
517 |
|
|
return r; |
518 |
jsr166 |
1.66 |
|
519 |
dl |
1.63 |
// Check if can terminate |
520 |
|
|
if (workQueue.isEmpty()) { |
521 |
|
|
interruptIdleWorkers(); |
522 |
|
|
return null; |
523 |
|
|
} |
524 |
jsr166 |
1.66 |
|
525 |
dl |
1.63 |
// Else there could still be delayed tasks in queue. |
526 |
dl |
1.16 |
return workQueue.take(); |
527 |
dl |
1.63 |
} |
528 |
jsr166 |
1.66 |
|
529 |
dl |
1.63 |
case STOP: |
530 |
dl |
1.16 |
return null; |
531 |
dl |
1.63 |
default: |
532 |
jsr166 |
1.66 |
assert false; |
533 |
dl |
1.16 |
} |
534 |
jsr166 |
1.66 |
} catch (InterruptedException ie) { |
535 |
dl |
1.63 |
// On interruption, re-check runstate |
536 |
dl |
1.16 |
} |
537 |
|
|
} |
538 |
|
|
} |
539 |
|
|
|
540 |
|
|
/** |
541 |
jsr166 |
1.66 |
* Wakes up all threads that might be waiting for tasks. |
542 |
dl |
1.16 |
*/ |
543 |
|
|
void interruptIdleWorkers() { |
544 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
545 |
dl |
1.16 |
mainLock.lock(); |
546 |
|
|
try { |
547 |
tim |
1.39 |
for (Worker w : workers) |
548 |
|
|
w.interruptIfIdle(); |
549 |
dl |
1.16 |
} finally { |
550 |
|
|
mainLock.unlock(); |
551 |
dl |
1.2 |
} |
552 |
|
|
} |
553 |
|
|
|
554 |
|
|
/** |
555 |
jsr166 |
1.66 |
* Performs bookkeeping for a terminated worker thread. |
556 |
tim |
1.10 |
* @param w the worker |
557 |
dl |
1.2 |
*/ |
558 |
dl |
1.52 |
void workerDone(Worker w) { |
559 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
560 |
dl |
1.2 |
mainLock.lock(); |
561 |
|
|
try { |
562 |
|
|
completedTaskCount += w.completedTasks; |
563 |
|
|
workers.remove(w); |
564 |
tim |
1.10 |
if (--poolSize > 0) |
565 |
dl |
1.2 |
return; |
566 |
|
|
|
567 |
dl |
1.16 |
// Else, this is the last thread. Deal with potential shutdown. |
568 |
|
|
|
569 |
|
|
int state = runState; |
570 |
|
|
assert state != TERMINATED; |
571 |
tim |
1.10 |
|
572 |
dl |
1.16 |
if (state != STOP) { |
573 |
|
|
// If there are queued tasks but no threads, create |
574 |
dl |
1.56 |
// replacement thread. We must create it initially |
575 |
|
|
// idle to avoid orphaned tasks in case addThread |
576 |
|
|
// fails. This also handles case of delayed tasks |
577 |
|
|
// that will sometime later become runnable. |
578 |
jsr166 |
1.66 |
if (!workQueue.isEmpty()) { |
579 |
dl |
1.56 |
Thread t = addThread(null); |
580 |
|
|
if (t != null) |
581 |
|
|
t.start(); |
582 |
dl |
1.16 |
return; |
583 |
|
|
} |
584 |
|
|
|
585 |
|
|
// Otherwise, we can exit without replacement |
586 |
|
|
if (state == RUNNING) |
587 |
|
|
return; |
588 |
dl |
1.2 |
} |
589 |
|
|
|
590 |
dl |
1.16 |
// Either state is STOP, or state is SHUTDOWN and there is |
591 |
|
|
// no work to do. So we can terminate. |
592 |
dl |
1.45 |
termination.signalAll(); |
593 |
dl |
1.16 |
runState = TERMINATED; |
594 |
|
|
// fall through to call terminate() outside of lock. |
595 |
tim |
1.14 |
} finally { |
596 |
dl |
1.2 |
mainLock.unlock(); |
597 |
|
|
} |
598 |
|
|
|
599 |
dl |
1.16 |
assert runState == TERMINATED; |
600 |
jsr166 |
1.66 |
terminated(); |
601 |
dl |
1.2 |
} |
602 |
|
|
|
603 |
|
|
/** |
604 |
tim |
1.10 |
* Worker threads |
605 |
dl |
1.2 |
*/ |
606 |
|
|
private class Worker implements Runnable { |
607 |
|
|
|
608 |
|
|
/** |
609 |
|
|
* The runLock is acquired and released surrounding each task |
610 |
|
|
* execution. It mainly protects against interrupts that are |
611 |
|
|
* intended to cancel the worker thread from instead |
612 |
|
|
* interrupting the task being run. |
613 |
|
|
*/ |
614 |
|
|
private final ReentrantLock runLock = new ReentrantLock(); |
615 |
|
|
|
616 |
|
|
/** |
617 |
|
|
* Initial task to run before entering run loop |
618 |
|
|
*/ |
619 |
|
|
private Runnable firstTask; |
620 |
|
|
|
621 |
|
|
/** |
622 |
|
|
* Per thread completed task counter; accumulated |
623 |
|
|
* into completedTaskCount upon termination. |
624 |
|
|
*/ |
625 |
|
|
volatile long completedTasks; |
626 |
|
|
|
627 |
|
|
/** |
628 |
|
|
* Thread this worker is running in. Acts as a final field, |
629 |
|
|
* but cannot be set until thread is created. |
630 |
|
|
*/ |
631 |
|
|
Thread thread; |
632 |
|
|
|
633 |
|
|
Worker(Runnable firstTask) { |
634 |
|
|
this.firstTask = firstTask; |
635 |
|
|
} |
636 |
|
|
|
637 |
|
|
boolean isActive() { |
638 |
|
|
return runLock.isLocked(); |
639 |
|
|
} |
640 |
|
|
|
641 |
|
|
/** |
642 |
jsr166 |
1.73 |
* Interrupts thread if not running a task. |
643 |
tim |
1.10 |
*/ |
644 |
dl |
1.2 |
void interruptIfIdle() { |
645 |
dl |
1.45 |
final ReentrantLock runLock = this.runLock; |
646 |
dl |
1.2 |
if (runLock.tryLock()) { |
647 |
|
|
try { |
648 |
|
|
thread.interrupt(); |
649 |
tim |
1.14 |
} finally { |
650 |
dl |
1.2 |
runLock.unlock(); |
651 |
|
|
} |
652 |
|
|
} |
653 |
|
|
} |
654 |
|
|
|
655 |
|
|
/** |
656 |
jsr166 |
1.73 |
* Interrupts thread even if running a task. |
657 |
tim |
1.10 |
*/ |
658 |
dl |
1.2 |
void interruptNow() { |
659 |
|
|
thread.interrupt(); |
660 |
|
|
} |
661 |
|
|
|
662 |
|
|
/** |
663 |
jsr166 |
1.73 |
* Runs a single task between before/after methods. |
664 |
dl |
1.2 |
*/ |
665 |
|
|
private void runTask(Runnable task) { |
666 |
dl |
1.45 |
final ReentrantLock runLock = this.runLock; |
667 |
dl |
1.2 |
runLock.lock(); |
668 |
|
|
try { |
669 |
dl |
1.65 |
Thread.interrupted(); // clear interrupt status on entry |
670 |
dl |
1.2 |
// Abort now if immediate cancel. Otherwise, we have |
671 |
|
|
// committed to run this task. |
672 |
dl |
1.16 |
if (runState == STOP) |
673 |
dl |
1.2 |
return; |
674 |
|
|
|
675 |
|
|
boolean ran = false; |
676 |
|
|
beforeExecute(thread, task); |
677 |
|
|
try { |
678 |
|
|
task.run(); |
679 |
|
|
ran = true; |
680 |
|
|
afterExecute(task, null); |
681 |
|
|
++completedTasks; |
682 |
jsr166 |
1.66 |
} catch (RuntimeException ex) { |
683 |
dl |
1.2 |
if (!ran) |
684 |
|
|
afterExecute(task, ex); |
685 |
dl |
1.17 |
// Else the exception occurred within |
686 |
dl |
1.2 |
// afterExecute itself in which case we don't |
687 |
|
|
// want to call it again. |
688 |
|
|
throw ex; |
689 |
|
|
} |
690 |
tim |
1.14 |
} finally { |
691 |
dl |
1.2 |
runLock.unlock(); |
692 |
|
|
} |
693 |
|
|
} |
694 |
|
|
|
695 |
|
|
/** |
696 |
|
|
* Main run loop |
697 |
|
|
*/ |
698 |
|
|
public void run() { |
699 |
|
|
try { |
700 |
dl |
1.50 |
Runnable task = firstTask; |
701 |
|
|
firstTask = null; |
702 |
|
|
while (task != null || (task = getTask()) != null) { |
703 |
dl |
1.2 |
runTask(task); |
704 |
|
|
task = null; // unnecessary but can help GC |
705 |
|
|
} |
706 |
tim |
1.14 |
} finally { |
707 |
dl |
1.2 |
workerDone(this); |
708 |
|
|
} |
709 |
|
|
} |
710 |
|
|
} |
711 |
tim |
1.1 |
|
712 |
dl |
1.17 |
// Public methods |
713 |
|
|
|
714 |
tim |
1.1 |
/** |
715 |
jsr166 |
1.67 |
* Creates a new <tt>ThreadPoolExecutor</tt> with the given initial |
716 |
|
|
* parameters and default thread factory and rejected execution handler. |
717 |
|
|
* It may be more convenient to use one of the {@link Executors} factory |
718 |
|
|
* methods instead of this general purpose constructor. |
719 |
tim |
1.1 |
* |
720 |
dl |
1.2 |
* @param corePoolSize the number of threads to keep in the |
721 |
tim |
1.1 |
* pool, even if they are idle. |
722 |
dl |
1.2 |
* @param maximumPoolSize the maximum number of threads to allow in the |
723 |
tim |
1.1 |
* pool. |
724 |
|
|
* @param keepAliveTime when the number of threads is greater than |
725 |
dl |
1.2 |
* the core, this is the maximum time that excess idle threads |
726 |
tim |
1.1 |
* will wait for new tasks before terminating. |
727 |
dl |
1.2 |
* @param unit the time unit for the keepAliveTime |
728 |
tim |
1.1 |
* argument. |
729 |
dl |
1.36 |
* @param workQueue the queue to use for holding tasks before they |
730 |
tim |
1.1 |
* are executed. This queue will hold only the <tt>Runnable</tt> |
731 |
|
|
* tasks submitted by the <tt>execute</tt> method. |
732 |
dl |
1.2 |
* @throws IllegalArgumentException if corePoolSize, or |
733 |
|
|
* keepAliveTime less than zero, or if maximumPoolSize less than or |
734 |
|
|
* equal to zero, or if corePoolSize greater than maximumPoolSize. |
735 |
tim |
1.1 |
* @throws NullPointerException if <tt>workQueue</tt> is null |
736 |
|
|
*/ |
737 |
dl |
1.2 |
public ThreadPoolExecutor(int corePoolSize, |
738 |
|
|
int maximumPoolSize, |
739 |
tim |
1.1 |
long keepAliveTime, |
740 |
dl |
1.2 |
TimeUnit unit, |
741 |
|
|
BlockingQueue<Runnable> workQueue) { |
742 |
tim |
1.10 |
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, |
743 |
dl |
1.34 |
Executors.defaultThreadFactory(), defaultHandler); |
744 |
dl |
1.2 |
} |
745 |
tim |
1.1 |
|
746 |
dl |
1.2 |
/** |
747 |
|
|
* Creates a new <tt>ThreadPoolExecutor</tt> with the given initial |
748 |
jsr166 |
1.67 |
* parameters and default rejected execution handler. |
749 |
dl |
1.2 |
* |
750 |
|
|
* @param corePoolSize the number of threads to keep in the |
751 |
|
|
* pool, even if they are idle. |
752 |
|
|
* @param maximumPoolSize the maximum number of threads to allow in the |
753 |
|
|
* pool. |
754 |
|
|
* @param keepAliveTime when the number of threads is greater than |
755 |
|
|
* the core, this is the maximum time that excess idle threads |
756 |
|
|
* will wait for new tasks before terminating. |
757 |
|
|
* @param unit the time unit for the keepAliveTime |
758 |
|
|
* argument. |
759 |
dl |
1.36 |
* @param workQueue the queue to use for holding tasks before they |
760 |
dl |
1.2 |
* are executed. This queue will hold only the <tt>Runnable</tt> |
761 |
|
|
* tasks submitted by the <tt>execute</tt> method. |
762 |
|
|
* @param threadFactory the factory to use when the executor |
763 |
tim |
1.10 |
* creates a new thread. |
764 |
dl |
1.2 |
* @throws IllegalArgumentException if corePoolSize, or |
765 |
|
|
* keepAliveTime less than zero, or if maximumPoolSize less than or |
766 |
|
|
* equal to zero, or if corePoolSize greater than maximumPoolSize. |
767 |
tim |
1.10 |
* @throws NullPointerException if <tt>workQueue</tt> |
768 |
dl |
1.2 |
* or <tt>threadFactory</tt> are null. |
769 |
|
|
*/ |
770 |
|
|
public ThreadPoolExecutor(int corePoolSize, |
771 |
|
|
int maximumPoolSize, |
772 |
|
|
long keepAliveTime, |
773 |
|
|
TimeUnit unit, |
774 |
|
|
BlockingQueue<Runnable> workQueue, |
775 |
|
|
ThreadFactory threadFactory) { |
776 |
tim |
1.10 |
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, |
777 |
dl |
1.2 |
threadFactory, defaultHandler); |
778 |
|
|
} |
779 |
tim |
1.1 |
|
780 |
dl |
1.2 |
/** |
781 |
|
|
* Creates a new <tt>ThreadPoolExecutor</tt> with the given initial |
782 |
jsr166 |
1.67 |
* parameters and default thread factory. |
783 |
dl |
1.2 |
* |
784 |
|
|
* @param corePoolSize the number of threads to keep in the |
785 |
|
|
* pool, even if they are idle. |
786 |
|
|
* @param maximumPoolSize the maximum number of threads to allow in the |
787 |
|
|
* pool. |
788 |
|
|
* @param keepAliveTime when the number of threads is greater than |
789 |
|
|
* the core, this is the maximum time that excess idle threads |
790 |
|
|
* will wait for new tasks before terminating. |
791 |
|
|
* @param unit the time unit for the keepAliveTime |
792 |
|
|
* argument. |
793 |
dl |
1.36 |
* @param workQueue the queue to use for holding tasks before they |
794 |
dl |
1.2 |
* are executed. This queue will hold only the <tt>Runnable</tt> |
795 |
|
|
* tasks submitted by the <tt>execute</tt> method. |
796 |
|
|
* @param handler the handler to use when execution is blocked |
797 |
|
|
* because the thread bounds and queue capacities are reached. |
798 |
|
|
* @throws IllegalArgumentException if corePoolSize, or |
799 |
|
|
* keepAliveTime less than zero, or if maximumPoolSize less than or |
800 |
|
|
* equal to zero, or if corePoolSize greater than maximumPoolSize. |
801 |
tim |
1.10 |
* @throws NullPointerException if <tt>workQueue</tt> |
802 |
jsr166 |
1.68 |
* or <tt>handler</tt> are null. |
803 |
dl |
1.2 |
*/ |
804 |
|
|
public ThreadPoolExecutor(int corePoolSize, |
805 |
|
|
int maximumPoolSize, |
806 |
|
|
long keepAliveTime, |
807 |
|
|
TimeUnit unit, |
808 |
|
|
BlockingQueue<Runnable> workQueue, |
809 |
|
|
RejectedExecutionHandler handler) { |
810 |
tim |
1.10 |
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, |
811 |
dl |
1.34 |
Executors.defaultThreadFactory(), handler); |
812 |
dl |
1.2 |
} |
813 |
tim |
1.1 |
|
814 |
dl |
1.2 |
/** |
815 |
|
|
* Creates a new <tt>ThreadPoolExecutor</tt> with the given initial |
816 |
|
|
* parameters. |
817 |
|
|
* |
818 |
|
|
* @param corePoolSize the number of threads to keep in the |
819 |
|
|
* pool, even if they are idle. |
820 |
|
|
* @param maximumPoolSize the maximum number of threads to allow in the |
821 |
|
|
* pool. |
822 |
|
|
* @param keepAliveTime when the number of threads is greater than |
823 |
|
|
* the core, this is the maximum time that excess idle threads |
824 |
|
|
* will wait for new tasks before terminating. |
825 |
|
|
* @param unit the time unit for the keepAliveTime |
826 |
|
|
* argument. |
827 |
dl |
1.36 |
* @param workQueue the queue to use for holding tasks before they |
828 |
dl |
1.2 |
* are executed. This queue will hold only the <tt>Runnable</tt> |
829 |
|
|
* tasks submitted by the <tt>execute</tt> method. |
830 |
|
|
* @param threadFactory the factory to use when the executor |
831 |
tim |
1.10 |
* creates a new thread. |
832 |
dl |
1.2 |
* @param handler the handler to use when execution is blocked |
833 |
|
|
* because the thread bounds and queue capacities are reached. |
834 |
|
|
* @throws IllegalArgumentException if corePoolSize, or |
835 |
|
|
* keepAliveTime less than zero, or if maximumPoolSize less than or |
836 |
|
|
* equal to zero, or if corePoolSize greater than maximumPoolSize. |
837 |
tim |
1.10 |
* @throws NullPointerException if <tt>workQueue</tt> |
838 |
dl |
1.2 |
* or <tt>threadFactory</tt> or <tt>handler</tt> are null. |
839 |
|
|
*/ |
840 |
|
|
public ThreadPoolExecutor(int corePoolSize, |
841 |
|
|
int maximumPoolSize, |
842 |
|
|
long keepAliveTime, |
843 |
|
|
TimeUnit unit, |
844 |
|
|
BlockingQueue<Runnable> workQueue, |
845 |
|
|
ThreadFactory threadFactory, |
846 |
|
|
RejectedExecutionHandler handler) { |
847 |
tim |
1.10 |
if (corePoolSize < 0 || |
848 |
dl |
1.2 |
maximumPoolSize <= 0 || |
849 |
tim |
1.10 |
maximumPoolSize < corePoolSize || |
850 |
dl |
1.2 |
keepAliveTime < 0) |
851 |
|
|
throw new IllegalArgumentException(); |
852 |
|
|
if (workQueue == null || threadFactory == null || handler == null) |
853 |
|
|
throw new NullPointerException(); |
854 |
|
|
this.corePoolSize = corePoolSize; |
855 |
|
|
this.maximumPoolSize = maximumPoolSize; |
856 |
|
|
this.workQueue = workQueue; |
857 |
|
|
this.keepAliveTime = unit.toNanos(keepAliveTime); |
858 |
|
|
this.threadFactory = threadFactory; |
859 |
|
|
this.handler = handler; |
860 |
tim |
1.1 |
} |
861 |
|
|
|
862 |
dl |
1.2 |
|
863 |
|
|
/** |
864 |
|
|
* Executes the given task sometime in the future. The task |
865 |
|
|
* may execute in a new thread or in an existing pooled thread. |
866 |
|
|
* |
867 |
|
|
* If the task cannot be submitted for execution, either because this |
868 |
|
|
* executor has been shutdown or because its capacity has been reached, |
869 |
tim |
1.10 |
* the task is handled by the current <tt>RejectedExecutionHandler</tt>. |
870 |
dl |
1.2 |
* |
871 |
|
|
* @param command the task to execute |
872 |
|
|
* @throws RejectedExecutionException at discretion of |
873 |
dl |
1.8 |
* <tt>RejectedExecutionHandler</tt>, if task cannot be accepted |
874 |
|
|
* for execution |
875 |
dl |
1.26 |
* @throws NullPointerException if command is null |
876 |
dl |
1.2 |
*/ |
877 |
tim |
1.10 |
public void execute(Runnable command) { |
878 |
dl |
1.26 |
if (command == null) |
879 |
|
|
throw new NullPointerException(); |
880 |
dl |
1.2 |
for (;;) { |
881 |
dl |
1.16 |
if (runState != RUNNING) { |
882 |
dl |
1.13 |
reject(command); |
883 |
dl |
1.2 |
return; |
884 |
|
|
} |
885 |
|
|
if (poolSize < corePoolSize && addIfUnderCorePoolSize(command)) |
886 |
|
|
return; |
887 |
|
|
if (workQueue.offer(command)) |
888 |
|
|
return; |
889 |
dl |
1.74 |
int status = addIfUnderMaximumPoolSize(command); |
890 |
|
|
if (status > 0) // created new thread |
891 |
dl |
1.2 |
return; |
892 |
dl |
1.74 |
if (status == 0) { // failed to create thread |
893 |
dl |
1.13 |
reject(command); |
894 |
dl |
1.2 |
return; |
895 |
|
|
} |
896 |
dl |
1.74 |
// Retry if created a new thread but it is busy with another task |
897 |
dl |
1.2 |
} |
898 |
tim |
1.1 |
} |
899 |
dl |
1.4 |
|
900 |
dl |
1.53 |
/** |
901 |
|
|
* Initiates an orderly shutdown in which previously submitted |
902 |
|
|
* tasks are executed, but no new tasks will be |
903 |
|
|
* accepted. Invocation has no additional effect if already shut |
904 |
|
|
* down. |
905 |
|
|
* @throws SecurityException if a security manager exists and |
906 |
|
|
* shutting down this ExecutorService may manipulate threads that |
907 |
|
|
* the caller is not permitted to modify because it does not hold |
908 |
|
|
* {@link java.lang.RuntimePermission}<tt>("modifyThread")</tt>, |
909 |
jsr166 |
1.68 |
* or the security manager's <tt>checkAccess</tt> method denies access. |
910 |
dl |
1.53 |
*/ |
911 |
dl |
1.2 |
public void shutdown() { |
912 |
jsr166 |
1.80 |
// Fail if caller doesn't have modifyThread permission. |
913 |
dl |
1.42 |
SecurityManager security = System.getSecurityManager(); |
914 |
jsr166 |
1.66 |
if (security != null) |
915 |
dl |
1.78 |
security.checkPermission(shutdownPerm); |
916 |
dl |
1.42 |
|
917 |
dl |
1.25 |
boolean fullyTerminated = false; |
918 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
919 |
dl |
1.2 |
mainLock.lock(); |
920 |
|
|
try { |
921 |
dl |
1.25 |
if (workers.size() > 0) { |
922 |
dl |
1.50 |
// Check if caller can modify worker threads. This |
923 |
|
|
// might not be true even if passed above check, if |
924 |
|
|
// the SecurityManager treats some threads specially. |
925 |
dl |
1.43 |
if (security != null) { |
926 |
|
|
for (Worker w: workers) |
927 |
|
|
security.checkAccess(w.thread); |
928 |
|
|
} |
929 |
|
|
|
930 |
|
|
int state = runState; |
931 |
|
|
if (state == RUNNING) // don't override shutdownNow |
932 |
dl |
1.25 |
runState = SHUTDOWN; |
933 |
dl |
1.43 |
|
934 |
|
|
try { |
935 |
|
|
for (Worker w: workers) |
936 |
|
|
w.interruptIfIdle(); |
937 |
jsr166 |
1.66 |
} catch (SecurityException se) { |
938 |
dl |
1.50 |
// If SecurityManager allows above checks, but |
939 |
|
|
// then unexpectedly throws exception when |
940 |
|
|
// interrupting threads (which it ought not do), |
941 |
|
|
// back out as cleanly as we can. Some threads may |
942 |
|
|
// have been killed but we remain in non-shutdown |
943 |
|
|
// state. |
944 |
jsr166 |
1.66 |
runState = state; |
945 |
dl |
1.43 |
throw se; |
946 |
|
|
} |
947 |
dl |
1.25 |
} |
948 |
|
|
else { // If no workers, trigger full termination now |
949 |
|
|
fullyTerminated = true; |
950 |
|
|
runState = TERMINATED; |
951 |
|
|
termination.signalAll(); |
952 |
|
|
} |
953 |
tim |
1.14 |
} finally { |
954 |
dl |
1.2 |
mainLock.unlock(); |
955 |
|
|
} |
956 |
dl |
1.25 |
if (fullyTerminated) |
957 |
|
|
terminated(); |
958 |
tim |
1.1 |
} |
959 |
|
|
|
960 |
dl |
1.16 |
|
961 |
dl |
1.53 |
/** |
962 |
|
|
* Attempts to stop all actively executing tasks, halts the |
963 |
jsr166 |
1.75 |
* processing of waiting tasks, and returns a list of the tasks |
964 |
|
|
* that were awaiting execution. |
965 |
jsr166 |
1.66 |
* |
966 |
jsr166 |
1.75 |
* <p>There are no guarantees beyond best-effort attempts to stop |
967 |
|
|
* processing actively executing tasks. This implementation |
968 |
|
|
* cancels tasks via {@link Thread#interrupt}, so any task that |
969 |
|
|
* fails to respond to interrupts may never terminate. |
970 |
dl |
1.53 |
* |
971 |
|
|
* @return list of tasks that never commenced execution |
972 |
|
|
* @throws SecurityException if a security manager exists and |
973 |
|
|
* shutting down this ExecutorService may manipulate threads that |
974 |
|
|
* the caller is not permitted to modify because it does not hold |
975 |
|
|
* {@link java.lang.RuntimePermission}<tt>("modifyThread")</tt>, |
976 |
|
|
* or the security manager's <tt>checkAccess</tt> method denies access. |
977 |
|
|
*/ |
978 |
tim |
1.39 |
public List<Runnable> shutdownNow() { |
979 |
dl |
1.43 |
// Almost the same code as shutdown() |
980 |
dl |
1.42 |
SecurityManager security = System.getSecurityManager(); |
981 |
jsr166 |
1.66 |
if (security != null) |
982 |
dl |
1.78 |
security.checkPermission(shutdownPerm); |
983 |
dl |
1.43 |
|
984 |
dl |
1.25 |
boolean fullyTerminated = false; |
985 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
986 |
dl |
1.2 |
mainLock.lock(); |
987 |
|
|
try { |
988 |
dl |
1.25 |
if (workers.size() > 0) { |
989 |
dl |
1.43 |
if (security != null) { |
990 |
|
|
for (Worker w: workers) |
991 |
|
|
security.checkAccess(w.thread); |
992 |
|
|
} |
993 |
|
|
|
994 |
|
|
int state = runState; |
995 |
|
|
if (state != TERMINATED) |
996 |
dl |
1.25 |
runState = STOP; |
997 |
dl |
1.43 |
try { |
998 |
|
|
for (Worker w : workers) |
999 |
|
|
w.interruptNow(); |
1000 |
jsr166 |
1.66 |
} catch (SecurityException se) { |
1001 |
dl |
1.43 |
runState = state; // back out; |
1002 |
|
|
throw se; |
1003 |
|
|
} |
1004 |
dl |
1.25 |
} |
1005 |
|
|
else { // If no workers, trigger full termination now |
1006 |
|
|
fullyTerminated = true; |
1007 |
|
|
runState = TERMINATED; |
1008 |
|
|
termination.signalAll(); |
1009 |
|
|
} |
1010 |
tim |
1.14 |
} finally { |
1011 |
dl |
1.2 |
mainLock.unlock(); |
1012 |
|
|
} |
1013 |
dl |
1.25 |
if (fullyTerminated) |
1014 |
|
|
terminated(); |
1015 |
tim |
1.41 |
return Arrays.asList(workQueue.toArray(EMPTY_RUNNABLE_ARRAY)); |
1016 |
tim |
1.1 |
} |
1017 |
|
|
|
1018 |
dl |
1.2 |
public boolean isShutdown() { |
1019 |
dl |
1.16 |
return runState != RUNNING; |
1020 |
|
|
} |
1021 |
|
|
|
1022 |
jsr166 |
1.66 |
/** |
1023 |
dl |
1.55 |
* Returns true if this executor is in the process of terminating |
1024 |
dl |
1.16 |
* after <tt>shutdown</tt> or <tt>shutdownNow</tt> but has not |
1025 |
|
|
* completely terminated. This method may be useful for |
1026 |
|
|
* debugging. A return of <tt>true</tt> reported a sufficient |
1027 |
|
|
* period after shutdown may indicate that submitted tasks have |
1028 |
|
|
* ignored or suppressed interruption, causing this executor not |
1029 |
|
|
* to properly terminate. |
1030 |
|
|
* @return true if terminating but not yet terminated. |
1031 |
|
|
*/ |
1032 |
|
|
public boolean isTerminating() { |
1033 |
|
|
return runState == STOP; |
1034 |
tim |
1.1 |
} |
1035 |
|
|
|
1036 |
dl |
1.2 |
public boolean isTerminated() { |
1037 |
dl |
1.16 |
return runState == TERMINATED; |
1038 |
dl |
1.2 |
} |
1039 |
tim |
1.1 |
|
1040 |
dl |
1.2 |
public boolean awaitTermination(long timeout, TimeUnit unit) |
1041 |
|
|
throws InterruptedException { |
1042 |
dl |
1.50 |
long nanos = unit.toNanos(timeout); |
1043 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
1044 |
dl |
1.2 |
mainLock.lock(); |
1045 |
|
|
try { |
1046 |
dl |
1.25 |
for (;;) { |
1047 |
jsr166 |
1.66 |
if (runState == TERMINATED) |
1048 |
dl |
1.25 |
return true; |
1049 |
|
|
if (nanos <= 0) |
1050 |
|
|
return false; |
1051 |
|
|
nanos = termination.awaitNanos(nanos); |
1052 |
|
|
} |
1053 |
tim |
1.14 |
} finally { |
1054 |
dl |
1.2 |
mainLock.unlock(); |
1055 |
|
|
} |
1056 |
dl |
1.15 |
} |
1057 |
|
|
|
1058 |
|
|
/** |
1059 |
|
|
* Invokes <tt>shutdown</tt> when this executor is no longer |
1060 |
|
|
* referenced. |
1061 |
jsr166 |
1.66 |
*/ |
1062 |
dl |
1.15 |
protected void finalize() { |
1063 |
|
|
shutdown(); |
1064 |
dl |
1.2 |
} |
1065 |
tim |
1.10 |
|
1066 |
dl |
1.2 |
/** |
1067 |
|
|
* Sets the thread factory used to create new threads. |
1068 |
|
|
* |
1069 |
|
|
* @param threadFactory the new thread factory |
1070 |
dl |
1.30 |
* @throws NullPointerException if threadFactory is null |
1071 |
tim |
1.11 |
* @see #getThreadFactory |
1072 |
dl |
1.2 |
*/ |
1073 |
|
|
public void setThreadFactory(ThreadFactory threadFactory) { |
1074 |
dl |
1.30 |
if (threadFactory == null) |
1075 |
|
|
throw new NullPointerException(); |
1076 |
dl |
1.2 |
this.threadFactory = threadFactory; |
1077 |
tim |
1.1 |
} |
1078 |
|
|
|
1079 |
dl |
1.2 |
/** |
1080 |
|
|
* Returns the thread factory used to create new threads. |
1081 |
|
|
* |
1082 |
|
|
* @return the current thread factory |
1083 |
tim |
1.11 |
* @see #setThreadFactory |
1084 |
dl |
1.2 |
*/ |
1085 |
|
|
public ThreadFactory getThreadFactory() { |
1086 |
|
|
return threadFactory; |
1087 |
tim |
1.1 |
} |
1088 |
|
|
|
1089 |
dl |
1.2 |
/** |
1090 |
|
|
* Sets a new handler for unexecutable tasks. |
1091 |
|
|
* |
1092 |
|
|
* @param handler the new handler |
1093 |
dl |
1.31 |
* @throws NullPointerException if handler is null |
1094 |
tim |
1.11 |
* @see #getRejectedExecutionHandler |
1095 |
dl |
1.2 |
*/ |
1096 |
|
|
public void setRejectedExecutionHandler(RejectedExecutionHandler handler) { |
1097 |
dl |
1.31 |
if (handler == null) |
1098 |
|
|
throw new NullPointerException(); |
1099 |
dl |
1.2 |
this.handler = handler; |
1100 |
|
|
} |
1101 |
tim |
1.1 |
|
1102 |
dl |
1.2 |
/** |
1103 |
|
|
* Returns the current handler for unexecutable tasks. |
1104 |
|
|
* |
1105 |
|
|
* @return the current handler |
1106 |
tim |
1.11 |
* @see #setRejectedExecutionHandler |
1107 |
dl |
1.2 |
*/ |
1108 |
|
|
public RejectedExecutionHandler getRejectedExecutionHandler() { |
1109 |
|
|
return handler; |
1110 |
tim |
1.1 |
} |
1111 |
|
|
|
1112 |
dl |
1.2 |
/** |
1113 |
dl |
1.17 |
* Returns the task queue used by this executor. Access to the |
1114 |
|
|
* task queue is intended primarily for debugging and monitoring. |
1115 |
dl |
1.27 |
* This queue may be in active use. Retrieving the task queue |
1116 |
dl |
1.2 |
* does not prevent queued tasks from executing. |
1117 |
|
|
* |
1118 |
|
|
* @return the task queue |
1119 |
|
|
*/ |
1120 |
|
|
public BlockingQueue<Runnable> getQueue() { |
1121 |
|
|
return workQueue; |
1122 |
tim |
1.1 |
} |
1123 |
dl |
1.4 |
|
1124 |
|
|
/** |
1125 |
dl |
1.44 |
* Removes this task from the executor's internal queue if it is |
1126 |
|
|
* present, thus causing it not to be run if it has not already |
1127 |
|
|
* started. |
1128 |
jsr166 |
1.66 |
* |
1129 |
dl |
1.44 |
* <p> This method may be useful as one part of a cancellation |
1130 |
|
|
* scheme. It may fail to remove tasks that have been converted |
1131 |
|
|
* into other forms before being placed on the internal queue. For |
1132 |
|
|
* example, a task entered using <tt>submit</tt> might be |
1133 |
|
|
* converted into a form that maintains <tt>Future</tt> status. |
1134 |
|
|
* However, in such cases, method {@link ThreadPoolExecutor#purge} |
1135 |
|
|
* may be used to remove those Futures that have been cancelled. |
1136 |
jsr166 |
1.66 |
* |
1137 |
dl |
1.8 |
* @param task the task to remove |
1138 |
|
|
* @return true if the task was removed |
1139 |
dl |
1.4 |
*/ |
1140 |
dl |
1.5 |
public boolean remove(Runnable task) { |
1141 |
dl |
1.4 |
return getQueue().remove(task); |
1142 |
|
|
} |
1143 |
|
|
|
1144 |
dl |
1.7 |
|
1145 |
|
|
/** |
1146 |
dl |
1.37 |
* Tries to remove from the work queue all {@link Future} |
1147 |
dl |
1.16 |
* tasks that have been cancelled. This method can be useful as a |
1148 |
|
|
* storage reclamation operation, that has no other impact on |
1149 |
|
|
* functionality. Cancelled tasks are never executed, but may |
1150 |
|
|
* accumulate in work queues until worker threads can actively |
1151 |
|
|
* remove them. Invoking this method instead tries to remove them now. |
1152 |
dl |
1.23 |
* However, this method may fail to remove tasks in |
1153 |
dl |
1.16 |
* the presence of interference by other threads. |
1154 |
dl |
1.7 |
*/ |
1155 |
|
|
public void purge() { |
1156 |
dl |
1.16 |
// Fail if we encounter interference during traversal |
1157 |
|
|
try { |
1158 |
|
|
Iterator<Runnable> it = getQueue().iterator(); |
1159 |
|
|
while (it.hasNext()) { |
1160 |
|
|
Runnable r = it.next(); |
1161 |
dl |
1.37 |
if (r instanceof Future<?>) { |
1162 |
|
|
Future<?> c = (Future<?>)r; |
1163 |
dl |
1.16 |
if (c.isCancelled()) |
1164 |
|
|
it.remove(); |
1165 |
|
|
} |
1166 |
dl |
1.7 |
} |
1167 |
|
|
} |
1168 |
jsr166 |
1.66 |
catch (ConcurrentModificationException ex) { |
1169 |
|
|
return; |
1170 |
dl |
1.16 |
} |
1171 |
dl |
1.7 |
} |
1172 |
tim |
1.1 |
|
1173 |
|
|
/** |
1174 |
dl |
1.2 |
* Sets the core number of threads. This overrides any value set |
1175 |
|
|
* in the constructor. If the new value is smaller than the |
1176 |
|
|
* current value, excess existing threads will be terminated when |
1177 |
dl |
1.34 |
* they next become idle. If larger, new threads will, if needed, |
1178 |
|
|
* be started to execute any queued tasks. |
1179 |
tim |
1.1 |
* |
1180 |
dl |
1.2 |
* @param corePoolSize the new core size |
1181 |
tim |
1.10 |
* @throws IllegalArgumentException if <tt>corePoolSize</tt> |
1182 |
dl |
1.8 |
* less than zero |
1183 |
tim |
1.11 |
* @see #getCorePoolSize |
1184 |
tim |
1.1 |
*/ |
1185 |
dl |
1.2 |
public void setCorePoolSize(int corePoolSize) { |
1186 |
|
|
if (corePoolSize < 0) |
1187 |
|
|
throw new IllegalArgumentException(); |
1188 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
1189 |
dl |
1.2 |
mainLock.lock(); |
1190 |
|
|
try { |
1191 |
|
|
int extra = this.corePoolSize - corePoolSize; |
1192 |
|
|
this.corePoolSize = corePoolSize; |
1193 |
tim |
1.38 |
if (extra < 0) { |
1194 |
dl |
1.56 |
int n = workQueue.size(); |
1195 |
|
|
// We have to create initially-idle threads here |
1196 |
|
|
// because we otherwise have no recourse about |
1197 |
|
|
// what to do with a dequeued task if addThread fails. |
1198 |
|
|
while (extra++ < 0 && n-- > 0 && poolSize < corePoolSize ) { |
1199 |
|
|
Thread t = addThread(null); |
1200 |
jsr166 |
1.66 |
if (t != null) |
1201 |
dl |
1.56 |
t.start(); |
1202 |
|
|
else |
1203 |
|
|
break; |
1204 |
|
|
} |
1205 |
tim |
1.38 |
} |
1206 |
|
|
else if (extra > 0 && poolSize > corePoolSize) { |
1207 |
dl |
1.2 |
Iterator<Worker> it = workers.iterator(); |
1208 |
tim |
1.10 |
while (it.hasNext() && |
1209 |
dl |
1.34 |
extra-- > 0 && |
1210 |
dl |
1.2 |
poolSize > corePoolSize && |
1211 |
jsr166 |
1.66 |
workQueue.remainingCapacity() == 0) |
1212 |
dl |
1.2 |
it.next().interruptIfIdle(); |
1213 |
|
|
} |
1214 |
tim |
1.14 |
} finally { |
1215 |
dl |
1.2 |
mainLock.unlock(); |
1216 |
|
|
} |
1217 |
|
|
} |
1218 |
tim |
1.1 |
|
1219 |
|
|
/** |
1220 |
dl |
1.2 |
* Returns the core number of threads. |
1221 |
tim |
1.1 |
* |
1222 |
dl |
1.2 |
* @return the core number of threads |
1223 |
tim |
1.11 |
* @see #setCorePoolSize |
1224 |
tim |
1.1 |
*/ |
1225 |
tim |
1.10 |
public int getCorePoolSize() { |
1226 |
dl |
1.2 |
return corePoolSize; |
1227 |
dl |
1.16 |
} |
1228 |
|
|
|
1229 |
|
|
/** |
1230 |
dl |
1.55 |
* Starts a core thread, causing it to idly wait for work. This |
1231 |
dl |
1.16 |
* overrides the default policy of starting core threads only when |
1232 |
|
|
* new tasks are executed. This method will return <tt>false</tt> |
1233 |
|
|
* if all core threads have already been started. |
1234 |
|
|
* @return true if a thread was started |
1235 |
jsr166 |
1.66 |
*/ |
1236 |
dl |
1.16 |
public boolean prestartCoreThread() { |
1237 |
|
|
return addIfUnderCorePoolSize(null); |
1238 |
|
|
} |
1239 |
|
|
|
1240 |
|
|
/** |
1241 |
dl |
1.55 |
* Starts all core threads, causing them to idly wait for work. This |
1242 |
dl |
1.16 |
* overrides the default policy of starting core threads only when |
1243 |
jsr166 |
1.66 |
* new tasks are executed. |
1244 |
dl |
1.16 |
* @return the number of threads started. |
1245 |
jsr166 |
1.66 |
*/ |
1246 |
dl |
1.16 |
public int prestartAllCoreThreads() { |
1247 |
|
|
int n = 0; |
1248 |
|
|
while (addIfUnderCorePoolSize(null)) |
1249 |
|
|
++n; |
1250 |
|
|
return n; |
1251 |
dl |
1.2 |
} |
1252 |
tim |
1.1 |
|
1253 |
|
|
/** |
1254 |
dl |
1.62 |
* Returns true if this pool allows core threads to time out and |
1255 |
|
|
* terminate if no tasks arrive within the keepAlive time, being |
1256 |
|
|
* replaced if needed when new tasks arrive. When true, the same |
1257 |
|
|
* keep-alive policy applying to non-core threads applies also to |
1258 |
|
|
* core threads. When false (the default), core threads are never |
1259 |
|
|
* terminated due to lack of incoming tasks. |
1260 |
|
|
* @return <tt>true</tt> if core threads are allowed to time out, |
1261 |
|
|
* else <tt>false</tt> |
1262 |
jsr166 |
1.72 |
* |
1263 |
|
|
* @since 1.6 |
1264 |
dl |
1.62 |
*/ |
1265 |
|
|
public boolean allowsCoreThreadTimeOut() { |
1266 |
|
|
return allowCoreThreadTimeOut; |
1267 |
|
|
} |
1268 |
|
|
|
1269 |
|
|
/** |
1270 |
|
|
* Sets the policy governing whether core threads may time out and |
1271 |
|
|
* terminate if no tasks arrive within the keep-alive time, being |
1272 |
|
|
* replaced if needed when new tasks arrive. When false, core |
1273 |
|
|
* threads are never terminated due to lack of incoming |
1274 |
|
|
* tasks. When true, the same keep-alive policy applying to |
1275 |
|
|
* non-core threads applies also to core threads. To avoid |
1276 |
|
|
* continual thread replacement, the keep-alive time must be |
1277 |
dl |
1.64 |
* greater than zero when setting <tt>true</tt>. This method |
1278 |
|
|
* should in general be called before the pool is actively used. |
1279 |
dl |
1.62 |
* @param value <tt>true</tt> if should time out, else <tt>false</tt> |
1280 |
dl |
1.64 |
* @throws IllegalArgumentException if value is <tt>true</tt> |
1281 |
|
|
* and the current keep-alive time is not greater than zero. |
1282 |
jsr166 |
1.72 |
* |
1283 |
|
|
* @since 1.6 |
1284 |
dl |
1.62 |
*/ |
1285 |
|
|
public void allowCoreThreadTimeOut(boolean value) { |
1286 |
dl |
1.64 |
if (value && keepAliveTime <= 0) |
1287 |
|
|
throw new IllegalArgumentException("Core threads must have nonzero keep alive times"); |
1288 |
|
|
|
1289 |
dl |
1.62 |
allowCoreThreadTimeOut = value; |
1290 |
|
|
} |
1291 |
|
|
|
1292 |
|
|
/** |
1293 |
tim |
1.1 |
* Sets the maximum allowed number of threads. This overrides any |
1294 |
dl |
1.2 |
* value set in the constructor. If the new value is smaller than |
1295 |
|
|
* the current value, excess existing threads will be |
1296 |
|
|
* terminated when they next become idle. |
1297 |
tim |
1.1 |
* |
1298 |
dl |
1.2 |
* @param maximumPoolSize the new maximum |
1299 |
|
|
* @throws IllegalArgumentException if maximumPoolSize less than zero or |
1300 |
|
|
* the {@link #getCorePoolSize core pool size} |
1301 |
tim |
1.11 |
* @see #getMaximumPoolSize |
1302 |
dl |
1.2 |
*/ |
1303 |
|
|
public void setMaximumPoolSize(int maximumPoolSize) { |
1304 |
|
|
if (maximumPoolSize <= 0 || maximumPoolSize < corePoolSize) |
1305 |
|
|
throw new IllegalArgumentException(); |
1306 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
1307 |
dl |
1.2 |
mainLock.lock(); |
1308 |
|
|
try { |
1309 |
|
|
int extra = this.maximumPoolSize - maximumPoolSize; |
1310 |
|
|
this.maximumPoolSize = maximumPoolSize; |
1311 |
|
|
if (extra > 0 && poolSize > maximumPoolSize) { |
1312 |
|
|
Iterator<Worker> it = workers.iterator(); |
1313 |
tim |
1.10 |
while (it.hasNext() && |
1314 |
|
|
extra > 0 && |
1315 |
dl |
1.2 |
poolSize > maximumPoolSize) { |
1316 |
|
|
it.next().interruptIfIdle(); |
1317 |
|
|
--extra; |
1318 |
|
|
} |
1319 |
|
|
} |
1320 |
tim |
1.14 |
} finally { |
1321 |
dl |
1.2 |
mainLock.unlock(); |
1322 |
|
|
} |
1323 |
|
|
} |
1324 |
tim |
1.1 |
|
1325 |
|
|
/** |
1326 |
|
|
* Returns the maximum allowed number of threads. |
1327 |
|
|
* |
1328 |
dl |
1.2 |
* @return the maximum allowed number of threads |
1329 |
tim |
1.11 |
* @see #setMaximumPoolSize |
1330 |
tim |
1.1 |
*/ |
1331 |
tim |
1.10 |
public int getMaximumPoolSize() { |
1332 |
dl |
1.2 |
return maximumPoolSize; |
1333 |
|
|
} |
1334 |
tim |
1.1 |
|
1335 |
|
|
/** |
1336 |
|
|
* Sets the time limit for which threads may remain idle before |
1337 |
dl |
1.2 |
* being terminated. If there are more than the core number of |
1338 |
tim |
1.1 |
* threads currently in the pool, after waiting this amount of |
1339 |
|
|
* time without processing a task, excess threads will be |
1340 |
|
|
* terminated. This overrides any value set in the constructor. |
1341 |
|
|
* @param time the time to wait. A time value of zero will cause |
1342 |
|
|
* excess threads to terminate immediately after executing tasks. |
1343 |
dl |
1.2 |
* @param unit the time unit of the time argument |
1344 |
dl |
1.64 |
* @throws IllegalArgumentException if time less than zero or |
1345 |
|
|
* if time is zero and allowsCoreThreadTimeOut |
1346 |
tim |
1.11 |
* @see #getKeepAliveTime |
1347 |
tim |
1.1 |
*/ |
1348 |
dl |
1.2 |
public void setKeepAliveTime(long time, TimeUnit unit) { |
1349 |
|
|
if (time < 0) |
1350 |
|
|
throw new IllegalArgumentException(); |
1351 |
dl |
1.64 |
if (time == 0 && allowsCoreThreadTimeOut()) |
1352 |
|
|
throw new IllegalArgumentException("Core threads must have nonzero keep alive times"); |
1353 |
dl |
1.2 |
this.keepAliveTime = unit.toNanos(time); |
1354 |
|
|
} |
1355 |
tim |
1.1 |
|
1356 |
|
|
/** |
1357 |
|
|
* Returns the thread keep-alive time, which is the amount of time |
1358 |
dl |
1.2 |
* which threads in excess of the core pool size may remain |
1359 |
tim |
1.10 |
* idle before being terminated. |
1360 |
tim |
1.1 |
* |
1361 |
dl |
1.2 |
* @param unit the desired time unit of the result |
1362 |
tim |
1.1 |
* @return the time limit |
1363 |
tim |
1.11 |
* @see #setKeepAliveTime |
1364 |
tim |
1.1 |
*/ |
1365 |
tim |
1.10 |
public long getKeepAliveTime(TimeUnit unit) { |
1366 |
dl |
1.2 |
return unit.convert(keepAliveTime, TimeUnit.NANOSECONDS); |
1367 |
|
|
} |
1368 |
tim |
1.1 |
|
1369 |
|
|
/* Statistics */ |
1370 |
|
|
|
1371 |
|
|
/** |
1372 |
|
|
* Returns the current number of threads in the pool. |
1373 |
|
|
* |
1374 |
|
|
* @return the number of threads |
1375 |
|
|
*/ |
1376 |
tim |
1.10 |
public int getPoolSize() { |
1377 |
dl |
1.2 |
return poolSize; |
1378 |
|
|
} |
1379 |
tim |
1.1 |
|
1380 |
|
|
/** |
1381 |
dl |
1.2 |
* Returns the approximate number of threads that are actively |
1382 |
tim |
1.1 |
* executing tasks. |
1383 |
|
|
* |
1384 |
|
|
* @return the number of threads |
1385 |
|
|
*/ |
1386 |
tim |
1.10 |
public int getActiveCount() { |
1387 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
1388 |
dl |
1.2 |
mainLock.lock(); |
1389 |
|
|
try { |
1390 |
|
|
int n = 0; |
1391 |
tim |
1.39 |
for (Worker w : workers) { |
1392 |
|
|
if (w.isActive()) |
1393 |
dl |
1.2 |
++n; |
1394 |
|
|
} |
1395 |
|
|
return n; |
1396 |
tim |
1.14 |
} finally { |
1397 |
dl |
1.2 |
mainLock.unlock(); |
1398 |
|
|
} |
1399 |
|
|
} |
1400 |
tim |
1.1 |
|
1401 |
|
|
/** |
1402 |
dl |
1.2 |
* Returns the largest number of threads that have ever |
1403 |
|
|
* simultaneously been in the pool. |
1404 |
tim |
1.1 |
* |
1405 |
|
|
* @return the number of threads |
1406 |
|
|
*/ |
1407 |
tim |
1.10 |
public int getLargestPoolSize() { |
1408 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
1409 |
dl |
1.2 |
mainLock.lock(); |
1410 |
|
|
try { |
1411 |
|
|
return largestPoolSize; |
1412 |
tim |
1.14 |
} finally { |
1413 |
dl |
1.2 |
mainLock.unlock(); |
1414 |
|
|
} |
1415 |
|
|
} |
1416 |
tim |
1.1 |
|
1417 |
|
|
/** |
1418 |
dl |
1.2 |
* Returns the approximate total number of tasks that have been |
1419 |
|
|
* scheduled for execution. Because the states of tasks and |
1420 |
|
|
* threads may change dynamically during computation, the returned |
1421 |
dl |
1.17 |
* value is only an approximation, but one that does not ever |
1422 |
|
|
* decrease across successive calls. |
1423 |
tim |
1.1 |
* |
1424 |
|
|
* @return the number of tasks |
1425 |
|
|
*/ |
1426 |
tim |
1.10 |
public long getTaskCount() { |
1427 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
1428 |
dl |
1.2 |
mainLock.lock(); |
1429 |
|
|
try { |
1430 |
|
|
long n = completedTaskCount; |
1431 |
tim |
1.39 |
for (Worker w : workers) { |
1432 |
dl |
1.2 |
n += w.completedTasks; |
1433 |
|
|
if (w.isActive()) |
1434 |
|
|
++n; |
1435 |
|
|
} |
1436 |
|
|
return n + workQueue.size(); |
1437 |
tim |
1.14 |
} finally { |
1438 |
dl |
1.2 |
mainLock.unlock(); |
1439 |
|
|
} |
1440 |
|
|
} |
1441 |
tim |
1.1 |
|
1442 |
|
|
/** |
1443 |
dl |
1.2 |
* Returns the approximate total number of tasks that have |
1444 |
|
|
* completed execution. Because the states of tasks and threads |
1445 |
|
|
* may change dynamically during computation, the returned value |
1446 |
dl |
1.17 |
* is only an approximation, but one that does not ever decrease |
1447 |
|
|
* across successive calls. |
1448 |
tim |
1.1 |
* |
1449 |
|
|
* @return the number of tasks |
1450 |
|
|
*/ |
1451 |
tim |
1.10 |
public long getCompletedTaskCount() { |
1452 |
dl |
1.45 |
final ReentrantLock mainLock = this.mainLock; |
1453 |
dl |
1.2 |
mainLock.lock(); |
1454 |
|
|
try { |
1455 |
|
|
long n = completedTaskCount; |
1456 |
tim |
1.39 |
for (Worker w : workers) |
1457 |
|
|
n += w.completedTasks; |
1458 |
dl |
1.2 |
return n; |
1459 |
tim |
1.14 |
} finally { |
1460 |
dl |
1.2 |
mainLock.unlock(); |
1461 |
|
|
} |
1462 |
|
|
} |
1463 |
tim |
1.1 |
|
1464 |
|
|
/** |
1465 |
dl |
1.17 |
* Method invoked prior to executing the given Runnable in the |
1466 |
dl |
1.43 |
* given thread. This method is invoked by thread <tt>t</tt> that |
1467 |
|
|
* will execute task <tt>r</tt>, and may be used to re-initialize |
1468 |
jsr166 |
1.73 |
* ThreadLocals, or to perform logging. |
1469 |
|
|
* |
1470 |
|
|
* <p>This implementation does nothing, but may be customized in |
1471 |
|
|
* subclasses. Note: To properly nest multiple overridings, subclasses |
1472 |
|
|
* should generally invoke <tt>super.beforeExecute</tt> at the end of |
1473 |
|
|
* this method. |
1474 |
tim |
1.1 |
* |
1475 |
dl |
1.2 |
* @param t the thread that will run task r. |
1476 |
|
|
* @param r the task that will be executed. |
1477 |
tim |
1.1 |
*/ |
1478 |
dl |
1.2 |
protected void beforeExecute(Thread t, Runnable r) { } |
1479 |
tim |
1.1 |
|
1480 |
|
|
/** |
1481 |
jsr166 |
1.70 |
* Method invoked upon completion of execution of the given Runnable. |
1482 |
|
|
* This method is invoked by the thread that executed the task. If |
1483 |
|
|
* non-null, the Throwable is the uncaught <tt>RuntimeException</tt> |
1484 |
|
|
* or <tt>Error</tt> that caused execution to terminate abruptly. |
1485 |
dl |
1.69 |
* |
1486 |
|
|
* <p><b>Note:</b> When actions are enclosed in tasks (such as |
1487 |
|
|
* {@link FutureTask}) either explicitly or via methods such as |
1488 |
|
|
* <tt>submit</tt>, these task objects catch and maintain |
1489 |
|
|
* computational exceptions, and so they do not cause abrupt |
1490 |
jsr166 |
1.70 |
* termination, and the internal exceptions are <em>not</em> |
1491 |
dl |
1.69 |
* passed to this method. |
1492 |
|
|
* |
1493 |
jsr166 |
1.70 |
* <p>This implementation does nothing, but may be customized in |
1494 |
|
|
* subclasses. Note: To properly nest multiple overridings, subclasses |
1495 |
|
|
* should generally invoke <tt>super.afterExecute</tt> at the |
1496 |
|
|
* beginning of this method. |
1497 |
tim |
1.1 |
* |
1498 |
dl |
1.2 |
* @param r the runnable that has completed. |
1499 |
dl |
1.24 |
* @param t the exception that caused termination, or null if |
1500 |
dl |
1.2 |
* execution completed normally. |
1501 |
tim |
1.1 |
*/ |
1502 |
dl |
1.2 |
protected void afterExecute(Runnable r, Throwable t) { } |
1503 |
tim |
1.1 |
|
1504 |
dl |
1.2 |
/** |
1505 |
|
|
* Method invoked when the Executor has terminated. Default |
1506 |
dl |
1.17 |
* implementation does nothing. Note: To properly nest multiple |
1507 |
|
|
* overridings, subclasses should generally invoke |
1508 |
|
|
* <tt>super.terminated</tt> within this method. |
1509 |
dl |
1.2 |
*/ |
1510 |
|
|
protected void terminated() { } |
1511 |
tim |
1.1 |
|
1512 |
|
|
/** |
1513 |
dl |
1.21 |
* A handler for rejected tasks that runs the rejected task |
1514 |
|
|
* directly in the calling thread of the <tt>execute</tt> method, |
1515 |
|
|
* unless the executor has been shut down, in which case the task |
1516 |
|
|
* is discarded. |
1517 |
tim |
1.1 |
*/ |
1518 |
jsr166 |
1.71 |
public static class CallerRunsPolicy implements RejectedExecutionHandler { |
1519 |
tim |
1.1 |
/** |
1520 |
dl |
1.24 |
* Creates a <tt>CallerRunsPolicy</tt>. |
1521 |
tim |
1.1 |
*/ |
1522 |
|
|
public CallerRunsPolicy() { } |
1523 |
|
|
|
1524 |
dl |
1.24 |
/** |
1525 |
|
|
* Executes task r in the caller's thread, unless the executor |
1526 |
|
|
* has been shut down, in which case the task is discarded. |
1527 |
|
|
* @param r the runnable task requested to be executed |
1528 |
|
|
* @param e the executor attempting to execute this task |
1529 |
|
|
*/ |
1530 |
dl |
1.2 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { |
1531 |
|
|
if (!e.isShutdown()) { |
1532 |
tim |
1.1 |
r.run(); |
1533 |
|
|
} |
1534 |
|
|
} |
1535 |
|
|
} |
1536 |
|
|
|
1537 |
|
|
/** |
1538 |
dl |
1.21 |
* A handler for rejected tasks that throws a |
1539 |
dl |
1.8 |
* <tt>RejectedExecutionException</tt>. |
1540 |
tim |
1.1 |
*/ |
1541 |
dl |
1.2 |
public static class AbortPolicy implements RejectedExecutionHandler { |
1542 |
tim |
1.1 |
/** |
1543 |
dl |
1.29 |
* Creates an <tt>AbortPolicy</tt>. |
1544 |
tim |
1.1 |
*/ |
1545 |
|
|
public AbortPolicy() { } |
1546 |
|
|
|
1547 |
dl |
1.24 |
/** |
1548 |
dl |
1.54 |
* Always throws RejectedExecutionException. |
1549 |
dl |
1.24 |
* @param r the runnable task requested to be executed |
1550 |
|
|
* @param e the executor attempting to execute this task |
1551 |
|
|
* @throws RejectedExecutionException always. |
1552 |
|
|
*/ |
1553 |
dl |
1.2 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { |
1554 |
|
|
throw new RejectedExecutionException(); |
1555 |
tim |
1.1 |
} |
1556 |
|
|
} |
1557 |
|
|
|
1558 |
|
|
/** |
1559 |
dl |
1.21 |
* A handler for rejected tasks that silently discards the |
1560 |
|
|
* rejected task. |
1561 |
tim |
1.1 |
*/ |
1562 |
dl |
1.2 |
public static class DiscardPolicy implements RejectedExecutionHandler { |
1563 |
tim |
1.1 |
/** |
1564 |
dl |
1.54 |
* Creates a <tt>DiscardPolicy</tt>. |
1565 |
tim |
1.1 |
*/ |
1566 |
|
|
public DiscardPolicy() { } |
1567 |
|
|
|
1568 |
dl |
1.24 |
/** |
1569 |
|
|
* Does nothing, which has the effect of discarding task r. |
1570 |
|
|
* @param r the runnable task requested to be executed |
1571 |
|
|
* @param e the executor attempting to execute this task |
1572 |
|
|
*/ |
1573 |
dl |
1.2 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { |
1574 |
tim |
1.1 |
} |
1575 |
|
|
} |
1576 |
|
|
|
1577 |
|
|
/** |
1578 |
dl |
1.21 |
* A handler for rejected tasks that discards the oldest unhandled |
1579 |
|
|
* request and then retries <tt>execute</tt>, unless the executor |
1580 |
|
|
* is shut down, in which case the task is discarded. |
1581 |
tim |
1.1 |
*/ |
1582 |
dl |
1.2 |
public static class DiscardOldestPolicy implements RejectedExecutionHandler { |
1583 |
tim |
1.1 |
/** |
1584 |
dl |
1.24 |
* Creates a <tt>DiscardOldestPolicy</tt> for the given executor. |
1585 |
tim |
1.1 |
*/ |
1586 |
|
|
public DiscardOldestPolicy() { } |
1587 |
|
|
|
1588 |
dl |
1.24 |
/** |
1589 |
|
|
* Obtains and ignores the next task that the executor |
1590 |
|
|
* would otherwise execute, if one is immediately available, |
1591 |
|
|
* and then retries execution of task r, unless the executor |
1592 |
|
|
* is shut down, in which case task r is instead discarded. |
1593 |
|
|
* @param r the runnable task requested to be executed |
1594 |
|
|
* @param e the executor attempting to execute this task |
1595 |
|
|
*/ |
1596 |
dl |
1.2 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { |
1597 |
|
|
if (!e.isShutdown()) { |
1598 |
|
|
e.getQueue().poll(); |
1599 |
|
|
e.execute(r); |
1600 |
tim |
1.1 |
} |
1601 |
|
|
} |
1602 |
|
|
} |
1603 |
|
|
} |