--- jsr166/src/jsr166y/ForkJoinPool.java 2009/01/12 17:16:18 1.4
+++ jsr166/src/jsr166y/ForkJoinPool.java 2009/07/22 01:36:51 1.13
@@ -27,7 +27,9 @@ import java.lang.reflect.*;
* (eventually blocking if none exist). This makes them efficient when
* most tasks spawn other subtasks (as do most ForkJoinTasks), as well
* as the mixed execution of some plain Runnable- or Callable- based
- * activities along with ForkJoinTasks. Otherwise, other
+ * activities along with ForkJoinTasks. When setting
+ * {@code setAsyncMode}, a ForkJoinPools may also be appropriate for
+ * use with fine-grained tasks that are never joined. Otherwise, other
* ExecutorService implementations are typically more appropriate
* choices.
*
@@ -36,24 +38,27 @@ import java.lang.reflect.*;
* adding, suspending, or resuming threads, even if some tasks are
* waiting to join others. However, no such adjustments are performed
* in the face of blocked IO or other unmanaged synchronization. The
- * nested ManagedBlocker
interface enables extension of
+ * nested {@code ManagedBlocker} interface enables extension of
* the kinds of synchronization accommodated. The target parallelism
- * level may also be changed dynamically (setParallelism
)
- * and dynamically thread construction can be limited using methods
- * setMaximumPoolSize
and/or
- * setMaintainsParallelism
.
+ * level may also be changed dynamically ({@code setParallelism})
+ * and thread construction can be limited using methods
+ * {@code setMaximumPoolSize} and/or
+ * {@code setMaintainsParallelism}.
*
*
In addition to execution and lifecycle control methods, this
* class provides status check methods (for example
- * getStealCount
) that are intended to aid in developing,
+ * {@code getStealCount}) that are intended to aid in developing,
* tuning, and monitoring fork/join applications. Also, method
- * toString
returns indications of pool state in a
+ * {@code toString} returns indications of pool state in a
* convenient form for informal monitoring.
*
*
Implementation notes: This implementation restricts the
* maximum number of running threads to 32767. Attempts to create
* pools with greater than the maximum result in
* IllegalArgumentExceptions.
+ *
+ * @since 1.7
+ * @author Doug Lea
*/
public class ForkJoinPool extends AbstractExecutorService {
@@ -79,7 +84,7 @@ public class ForkJoinPool extends Abstra
* Returns a new worker thread operating in the given pool.
*
* @param pool the pool this thread works in
- * @throws NullPointerException if pool is null;
+ * @throws NullPointerException if pool is null
*/
public ForkJoinWorkerThread newThread(ForkJoinPool pool);
}
@@ -131,11 +136,11 @@ public class ForkJoinPool extends Abstra
new AtomicInteger();
/**
- * Array holding all worker threads in the pool. Array size must
- * be a power of two. Updates and replacements are protected by
- * workerLock, but it is always kept in a consistent enough state
- * to be randomly accessed without locking by workers performing
- * work-stealing.
+ * Array holding all worker threads in the pool. Initialized upon
+ * first use. Array size must be a power of two. Updates and
+ * replacements are protected by workerLock, but it is always kept
+ * in a consistent enough state to be randomly accessed without
+ * locking by workers performing work-stealing.
*/
volatile ForkJoinWorkerThread[] workers;
@@ -151,7 +156,7 @@ public class ForkJoinPool extends Abstra
/**
* The uncaught exception handler used when any worker
- * abrupty terminates
+ * abruptly terminates
*/
private Thread.UncaughtExceptionHandler ueh;
@@ -204,6 +209,11 @@ public class ForkJoinPool extends Abstra
private volatile int parallelism;
/**
+ * True if use local fifo, not default lifo, for local polling
+ */
+ private volatile boolean locallyFifo;
+
+ /**
* Holds number of total (i.e., created and not yet terminated)
* and running (i.e., not blocked on joins or other managed sync)
* threads, packed into one int to ensure consistent snapshot when
@@ -219,9 +229,9 @@ public class ForkJoinPool extends Abstra
private static int workerCountsFor(int t, int r) { return (t << 16) + r; }
/**
- * Add delta (which may be negative) to running count. This must
+ * Adds delta (which may be negative) to running count. This must
* be called before (with negative arg) and after (with positive)
- * any managed synchronization (i.e., mainly, joins)
+ * any managed synchronization (i.e., mainly, joins).
* @param delta the number to add
*/
final void updateRunningCount(int delta) {
@@ -230,7 +240,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Add delta (which may be negative) to both total and running
+ * Adds delta (which may be negative) to both total and running
* count. This must be called upon creation and termination of
* worker threads.
* @param delta the number to add
@@ -266,7 +276,7 @@ public class ForkJoinPool extends Abstra
/**
* Try incrementing active count; fail on contention. Called by
* workers before/during executing tasks.
- * @return true on success;
+ * @return true on success
*/
final boolean tryIncrementActiveCount() {
int c = runControl;
@@ -274,8 +284,8 @@ public class ForkJoinPool extends Abstra
}
/**
- * Try decrementing active count; fail on contention.
- * Possibly trigger termination on success
+ * Tries decrementing active count; fails on contention.
+ * Possibly triggers termination on success.
* Called by workers when they can't find tasks.
* @return true on success
*/
@@ -290,7 +300,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Return true if argument represents zero active count and
+ * Returns true if argument represents zero active count and
* nonzero runstate, which is the triggering condition for
* terminating on shutdown.
*/
@@ -326,7 +336,7 @@ public class ForkJoinPool extends Abstra
* @throws SecurityException if a security manager exists and
* the caller is not permitted to modify threads
* because it does not hold {@link
- * java.lang.RuntimePermission} For example, here is a ManagedBlocker based on a
@@ -1620,9 +1720,9 @@ public class ForkJoinPool extends Abstra
* Possibly blocks the current thread, for example waiting for
* a lock or condition.
* @return true if no additional blocking is necessary (i.e.,
- * if isReleasable would return true).
+ * if isReleasable would return true)
* @throws InterruptedException if interrupted while waiting
- * (the method is not required to do so, but is allowe to).
+ * (the method is not required to do so, but is allowed to).
*/
boolean block() throws InterruptedException;
@@ -1637,7 +1737,7 @@ public class ForkJoinPool extends Abstra
* is a ForkJoinWorkerThread, this method possibly arranges for a
* spare thread to be activated if necessary to ensure parallelism
* while the current thread is blocked. If
- * ("modifyThread")
,
+ * java.lang.RuntimePermission}{@code ("modifyThread")},
*/
public ForkJoinPool() {
this(Runtime.getRuntime().availableProcessors(),
@@ -334,7 +344,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Creates a ForkJoinPool with the indicated parellelism level
+ * Creates a ForkJoinPool with the indicated parallelism level
* threads, and using the default ForkJoinWorkerThreadFactory,
* @param parallelism the number of worker threads
* @throws IllegalArgumentException if parallelism less than or
@@ -342,7 +352,7 @@ public class ForkJoinPool extends Abstra
* @throws SecurityException if a security manager exists and
* the caller is not permitted to modify threads
* because it does not hold {@link
- * java.lang.RuntimePermission}("modifyThread")
,
+ * java.lang.RuntimePermission}{@code ("modifyThread")},
*/
public ForkJoinPool(int parallelism) {
this(parallelism, defaultForkJoinWorkerThreadFactory);
@@ -357,7 +367,7 @@ public class ForkJoinPool extends Abstra
* @throws SecurityException if a security manager exists and
* the caller is not permitted to modify threads
* because it does not hold {@link
- * java.lang.RuntimePermission}("modifyThread")
,
+ * java.lang.RuntimePermission}{@code ("modifyThread")},
*/
public ForkJoinPool(ForkJoinWorkerThreadFactory factory) {
this(Runtime.getRuntime().availableProcessors(), factory);
@@ -369,12 +379,12 @@ public class ForkJoinPool extends Abstra
* @param parallelism the targeted number of worker threads
* @param factory the factory for creating new threads
* @throws IllegalArgumentException if parallelism less than or
- * equal to zero, or greater than implementation limit.
+ * equal to zero, or greater than implementation limit
* @throws NullPointerException if factory is null
* @throws SecurityException if a security manager exists and
* the caller is not permitted to modify threads
* because it does not hold {@link
- * java.lang.RuntimePermission}("modifyThread")
,
+ * java.lang.RuntimePermission}{@code ("modifyThread")},
*/
public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) {
if (parallelism <= 0 || parallelism > MAX_THREADS)
@@ -391,7 +401,7 @@ public class ForkJoinPool extends Abstra
this.termination = workerLock.newCondition();
this.stealCount = new AtomicLong();
this.submissionQueue = new LinkedTransferQueue("modifyThread")
,
+ * java.lang.RuntimePermission}{@code ("modifyThread")},
*/
public Thread.UncaughtExceptionHandler
setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
@@ -683,10 +704,12 @@ public class ForkJoinPool extends Abstra
old = ueh;
ueh = h;
ForkJoinWorkerThread[] ws = workers;
- for (int i = 0; i < ws.length; ++i) {
- ForkJoinWorkerThread w = ws[i];
- if (w != null)
- w.setUncaughtExceptionHandler(h);
+ if (ws != null) {
+ for (int i = 0; i < ws.length; ++i) {
+ ForkJoinWorkerThread w = ws[i];
+ if (w != null)
+ w.setUncaughtExceptionHandler(h);
+ }
}
} finally {
lock.unlock();
@@ -696,14 +719,14 @@ public class ForkJoinPool extends Abstra
/**
- * Sets the target paralleism level of this pool.
+ * Sets the target parallelism level of this pool.
* @param parallelism the target parallelism
* @throws IllegalArgumentException if parallelism less than or
- * equal to zero or greater than maximum size bounds.
+ * equal to zero or greater than maximum size bounds
* @throws SecurityException if a security manager exists and
* the caller is not permitted to modify threads
* because it does not hold {@link
- * java.lang.RuntimePermission}("modifyThread")
,
+ * java.lang.RuntimePermission}{@code ("modifyThread")},
*/
public void setParallelism(int parallelism) {
checkPermission();
@@ -738,7 +761,7 @@ public class ForkJoinPool extends Abstra
/**
* Returns the number of worker threads that have started but not
* yet terminated. This result returned by this method may differ
- * from getParallelism
when threads are created to
+ * from {@code getParallelism} when threads are created to
* maintain parallelism when others are cooperatively blocked.
*
* @return the number of worker threads
@@ -762,7 +785,7 @@ public class ForkJoinPool extends Abstra
* Setting this value has no effect on current pool size. It
* controls construction of new threads.
* @throws IllegalArgumentException if negative or greater then
- * internal implementation limit.
+ * internal implementation limit
*/
public void setMaximumPoolSize(int newMax) {
if (newMax < 0 || newMax > MAX_THREADS)
@@ -793,6 +816,42 @@ public class ForkJoinPool extends Abstra
}
/**
+ * Establishes local first-in-first-out scheduling mode for forked
+ * tasks that are never joined. This mode may be more appropriate
+ * than default locally stack-based mode in applications in which
+ * worker threads only process asynchronous tasks. This method is
+ * designed to be invoked only when pool is quiescent, and
+ * typically only before any tasks are submitted. The effects of
+ * invocations at other times may be unpredictable.
+ *
+ * @param async if true, use locally FIFO scheduling
+ * @return the previous mode
+ */
+ public boolean setAsyncMode(boolean async) {
+ boolean oldMode = locallyFifo;
+ locallyFifo = async;
+ ForkJoinWorkerThread[] ws = workers;
+ if (ws != null) {
+ for (int i = 0; i < ws.length; ++i) {
+ ForkJoinWorkerThread t = ws[i];
+ if (t != null)
+ t.setAsyncMode(async);
+ }
+ }
+ return oldMode;
+ }
+
+ /**
+ * Returns true if this pool uses local first-in-first-out
+ * scheduling mode for forked tasks that are never joined.
+ *
+ * @return true if this pool uses async mode
+ */
+ public boolean getAsyncMode() {
+ return locallyFifo;
+ }
+
+ /**
* Returns an estimate of the number of worker threads that are
* not blocked waiting to join tasks or for other managed
* synchronization.
@@ -807,7 +866,7 @@ public class ForkJoinPool extends Abstra
* Returns an estimate of the number of threads that are currently
* stealing or executing tasks. This method may overestimate the
* number of active threads.
- * @return the number of active threads.
+ * @return the number of active threads
*/
public int getActiveThreadCount() {
return activeCountOf(runControl);
@@ -817,7 +876,7 @@ public class ForkJoinPool extends Abstra
* Returns an estimate of the number of threads that are currently
* idle waiting for tasks. This method may underestimate the
* number of idle threads.
- * @return the number of idle threads.
+ * @return the number of idle threads
*/
final int getIdleThreadCount() {
int c = runningCountOf(workerCounts) - activeCountOf(runControl);
@@ -846,7 +905,7 @@ public class ForkJoinPool extends Abstra
* tuning fork/join programs: In general, steal counts should be
* high enough to keep threads busy, but low enough to avoid
* overhead and contention across threads.
- * @return the number of steals.
+ * @return the number of steals
*/
public long getStealCount() {
return stealCount.get();
@@ -869,15 +928,17 @@ public class ForkJoinPool extends Abstra
* an approximation, obtained by iterating across all threads in
* the pool. This method may be useful for tuning task
* granularities.
- * @return the number of queued tasks.
+ * @return the number of queued tasks
*/
public long getQueuedTaskCount() {
long count = 0;
ForkJoinWorkerThread[] ws = workers;
- for (int i = 0; i < ws.length; ++i) {
- ForkJoinWorkerThread t = ws[i];
- if (t != null)
- count += t.getQueueSize();
+ if (ws != null) {
+ for (int i = 0; i < ws.length; ++i) {
+ ForkJoinWorkerThread t = ws[i];
+ if (t != null)
+ count += t.getQueueSize();
+ }
}
return count;
}
@@ -886,7 +947,7 @@ public class ForkJoinPool extends Abstra
* Returns an estimate of the number tasks submitted to this pool
* that have not yet begun executing. This method takes time
* proportional to the number of submissions.
- * @return the number of queued submissions.
+ * @return the number of queued submissions
*/
public int getQueuedSubmissionCount() {
return submissionQueue.size();
@@ -895,7 +956,7 @@ public class ForkJoinPool extends Abstra
/**
* Returns true if there are any tasks submitted to this pool
* that have not yet begun executing.
- * @return true
if there are any queued submissions.
+ * @return {@code true} if there are any queued submissions
*/
public boolean hasQueuedSubmissions() {
return !submissionQueue.isEmpty();
@@ -912,6 +973,35 @@ public class ForkJoinPool extends Abstra
}
/**
+ * Removes all available unexecuted submitted and forked tasks
+ * from scheduling queues and adds them to the given collection,
+ * without altering their execution status. These may include
+ * artificially generated or wrapped tasks. This method is designed
+ * to be invoked only when the pool is known to be
+ * quiescent. Invocations at other times may not remove all
+ * tasks. A failure encountered while attempting to add elements
+ * to collection {@code c} may result in elements being in
+ * neither, either or both collections when the associated
+ * exception is thrown. The behavior of this operation is
+ * undefined if the specified collection is modified while the
+ * operation is in progress.
+ * @param c the collection to transfer elements into
+ * @return the number of elements transferred
+ */
+ protected int drainTasksTo(Collection("modifyThread")
,
+ * java.lang.RuntimePermission}{@code ("modifyThread")},
*/
public void shutdown() {
checkPermission();
@@ -972,13 +1062,15 @@ public class ForkJoinPool extends Abstra
* waiting tasks. Tasks that are in the process of being
* submitted or executed concurrently during the course of this
* method may or may not be rejected. Unlike some other executors,
- * this method cancels rather than collects non-executed tasks,
- * so always returns an empty list.
+ * this method cancels rather than collects non-executed tasks
+ * upon termination, so always returns an empty list. However, you
+ * can use method {@code drainTasksTo} before invoking this
+ * method to transfer unexecuted tasks to another collection.
* @return an empty list
* @throws SecurityException if a security manager exists and
* the caller is not permitted to modify threads
* because it does not hold {@link
- * java.lang.RuntimePermission}("modifyThread")
,
+ * java.lang.RuntimePermission}{@code ("modifyThread")},
*/
public Listtrue
if all tasks have completed following shut down.
+ * Returns {@code true} if all tasks have completed following shut down.
*
- * @return true
if all tasks have completed following shut down
+ * @return {@code true} if all tasks have completed following shut down
*/
public boolean isTerminated() {
return runStateOf(runControl) == TERMINATED;
}
/**
- * Returns true
if the process of termination has
+ * Returns {@code true} if the process of termination has
* commenced but possibly not yet completed.
*
- * @return true
if terminating
+ * @return {@code true} if terminating
*/
public boolean isTerminating() {
return runStateOf(runControl) >= TERMINATING;
}
/**
- * Returns true
if this pool has been shut down.
+ * Returns {@code true} if this pool has been shut down.
*
- * @return true
if this pool has been shut down
+ * @return {@code true} if this pool has been shut down
*/
public boolean isShutdown() {
return runStateOf(runControl) >= SHUTDOWN;
@@ -1021,8 +1113,8 @@ public class ForkJoinPool extends Abstra
*
* @param timeout the maximum time to wait
* @param unit the time unit of the timeout argument
- * @return true
if this executor terminated and
- * false
if the timeout elapsed before termination
+ * @return {@code true} if this executor terminated and
+ * {@code false} if the timeout elapsed before termination
* @throws InterruptedException if interrupted while waiting
*/
public boolean awaitTermination(long timeout, TimeUnit unit)
@@ -1058,17 +1150,19 @@ public class ForkJoinPool extends Abstra
lock.lock();
try {
ForkJoinWorkerThread[] ws = workers;
- int idx = w.poolIndex;
- if (idx >= 0 && idx < ws.length && ws[idx] == w)
- ws[idx] = null;
- if (totalCountOf(workerCounts) == 0) {
- terminate(); // no-op if already terminating
- transitionRunStateTo(TERMINATED);
- termination.signalAll();
- }
- else if (!isTerminating()) {
- tryShrinkWorkerArray();
- tryResumeSpare(true); // allow replacement
+ if (ws != null) {
+ int idx = w.poolIndex;
+ if (idx >= 0 && idx < ws.length && ws[idx] == w)
+ ws[idx] = null;
+ if (totalCountOf(workerCounts) == 0) {
+ terminate(); // no-op if already terminating
+ transitionRunStateTo(TERMINATED);
+ termination.signalAll();
+ }
+ else if (!isTerminating()) {
+ tryShrinkWorkerArray();
+ tryResumeSpare(true); // allow replacement
+ }
}
} finally {
lock.unlock();
@@ -1092,7 +1186,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Possibly terminate when on shutdown state
+ * Possibly terminates when on shutdown state.
*/
private void terminateOnShutdown() {
if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
@@ -1100,7 +1194,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Clear out and cancel submissions
+ * Clears out and cancels submissions.
*/
private void cancelQueuedSubmissions() {
ForkJoinTask> task;
@@ -1109,17 +1203,19 @@ public class ForkJoinPool extends Abstra
}
/**
- * Clean out worker queues.
+ * Cleans out worker queues.
*/
private void cancelQueuedWorkerTasks() {
final ReentrantLock lock = this.workerLock;
lock.lock();
try {
ForkJoinWorkerThread[] ws = workers;
- for (int i = 0; i < ws.length; ++i) {
- ForkJoinWorkerThread t = ws[i];
- if (t != null)
- t.cancelTasks();
+ if (ws != null) {
+ for (int i = 0; i < ws.length; ++i) {
+ ForkJoinWorkerThread t = ws[i];
+ if (t != null)
+ t.cancelTasks();
+ }
}
} finally {
lock.unlock();
@@ -1127,18 +1223,20 @@ public class ForkJoinPool extends Abstra
}
/**
- * Set each worker's status to terminating. Requires lock to avoid
- * conflicts with add/remove
+ * Sets each worker's status to terminating. Requires lock to avoid
+ * conflicts with add/remove.
*/
private void stopAllWorkers() {
final ReentrantLock lock = this.workerLock;
lock.lock();
try {
ForkJoinWorkerThread[] ws = workers;
- for (int i = 0; i < ws.length; ++i) {
- ForkJoinWorkerThread t = ws[i];
- if (t != null)
- t.shutdownNow();
+ if (ws != null) {
+ for (int i = 0; i < ws.length; ++i) {
+ ForkJoinWorkerThread t = ws[i];
+ if (t != null)
+ t.shutdownNow();
+ }
}
} finally {
lock.unlock();
@@ -1146,7 +1244,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Interrupt all unterminated workers. This is not required for
+ * Interrupts all unterminated workers. This is not required for
* sake of internal control, but may help unstick user code during
* shutdown.
*/
@@ -1155,12 +1253,14 @@ public class ForkJoinPool extends Abstra
lock.lock();
try {
ForkJoinWorkerThread[] ws = workers;
- for (int i = 0; i < ws.length; ++i) {
- ForkJoinWorkerThread t = ws[i];
- if (t != null && !t.isTerminated()) {
- try {
- t.interrupt();
- } catch (SecurityException ignore) {
+ if (ws != null) {
+ for (int i = 0; i < ws.length; ++i) {
+ ForkJoinWorkerThread t = ws[i];
+ if (t != null && !t.isTerminated()) {
+ try {
+ t.interrupt();
+ } catch (SecurityException ignore) {
+ }
}
}
}
@@ -1214,7 +1314,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Wake up waiter, returning false if known to already
+ * Wakes up waiter, returning false if known to already
*/
boolean signal() {
ForkJoinWorkerThread t = thread;
@@ -1226,7 +1326,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Await release on sync
+ * Awaits release on sync.
*/
void awaitSyncRelease(ForkJoinPool p) {
while (thread != null && !p.syncIsReleasable(this))
@@ -1234,7 +1334,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Await resumption as spare
+ * Awaits resumption as spare.
*/
void awaitSpareRelease() {
while (thread != null) {
@@ -1274,7 +1374,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Signal threads waiting to poll a task. Because method sync
+ * Signals threads waiting to poll a task. Because method sync
* rechecks availability, it is OK to only proceed if queue
* appears to be non-empty, and OK to skip under contention to
* increment count (since some other thread succeeded).
@@ -1302,7 +1402,7 @@ public class ForkJoinPool extends Abstra
long prev = w.lastEventCount;
WaitQueueNode node = null;
WaitQueueNode h;
- while (eventCount == prev &&
+ while (eventCount == prev &&
((h = syncStack) == null || h.count == prev)) {
if (node == null)
node = new WaitQueueNode(prev, w);
@@ -1324,8 +1424,8 @@ public class ForkJoinPool extends Abstra
* - on signal (thread == null)
* - on event count advance (winning race to notify vs signaller)
* - on Interrupt
- * - if the first queued node, we find work available
- * If node was not signalled and event count not advanced on exit,
+ * - if the first queued node, we find work available
+ * If node was not signalled and event count not advanced on exit,
* then we also help advance event count.
* @return true if node can be released
*/
@@ -1361,7 +1461,7 @@ public class ForkJoinPool extends Abstra
// Parallelism maintenance
/**
- * Decrement running count; if too low, add spare.
+ * Decrements running count; if too low, adds spare.
*
* Conceptually, all we need to do here is add or resume a
* spare thread when one is about to block (and remove or
@@ -1381,7 +1481,7 @@ public class ForkJoinPool extends Abstra
* only be suspended or removed when they are idle, not
* immediately when they aren't needed. So adding threads will
* raise parallelism level for longer than necessary. Also,
- * FJ applications often enounter highly transient peaks when
+ * FJ applications often encounter highly transient peaks when
* many threads are blocked joining, but for less time than it
* takes to create or resume spares.
*
@@ -1446,13 +1546,13 @@ public class ForkJoinPool extends Abstra
return (tc < maxPoolSize &&
(rc == 0 || totalSurplus < 0 ||
(maintainParallelism &&
- runningDeficit > totalSurplus &&
+ runningDeficit > totalSurplus &&
ForkJoinWorkerThread.hasQueuedTasks(workers))));
}
-
+
/**
- * Add a spare worker if lock available and no more than the
- * expected numbers of threads exist
+ * Adds a spare worker if lock available and no more than the
+ * expected numbers of threads exist.
* @return true if successful
*/
private boolean tryAddSpare(int expectedCounts) {
@@ -1485,7 +1585,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Add the kth spare worker. On entry, pool coounts are already
+ * Adds the kth spare worker. On entry, pool counts are already
* adjusted to reflect addition.
*/
private void createAndStartSpare(int k) {
@@ -1507,11 +1607,11 @@ public class ForkJoinPool extends Abstra
}
/**
- * Suspend calling thread w if there are excess threads. Called
- * only from sync. Spares are enqueued in a Treiber stack
- * using the same WaitQueueNodes as barriers. They are resumed
- * mainly in preJoin, but are also woken on pool events that
- * require all threads to check run state.
+ * Suspends calling thread w if there are excess threads. Called
+ * only from sync. Spares are enqueued in a Treiber stack using
+ * the same WaitQueueNodes as barriers. They are resumed mainly
+ * in preJoin, but are also woken on pool events that require all
+ * threads to check run state.
* @param w the caller
*/
private boolean suspendIfSpare(ForkJoinWorkerThread w) {
@@ -1532,7 +1632,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Try to pop and resume a spare thread.
+ * Tries to pop and resume a spare thread.
* @param updateCount if true, increment running count on success
* @return true if successful
*/
@@ -1550,7 +1650,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Pop and resume all spare threads. Same idea as ensureSync.
+ * Pops and resumes all spare threads. Same idea as ensureSync.
* @return true if any spares released
*/
private boolean resumeAllSpares() {
@@ -1568,7 +1668,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Pop and shutdown excessive spare threads. Call only while
+ * Pops and shuts down excessive spare threads. Call only while
* holding lock. This is not guaranteed to eliminate all excess
* threads, only those suspended as spares, which are the ones
* unlikely to be needed in the future.
@@ -1593,8 +1693,8 @@ public class ForkJoinPool extends Abstra
/**
* Interface for extending managed parallelism for tasks running
* in ForkJoinPools. A ManagedBlocker provides two methods.
- * Method isReleasable
must return true if blocking is not
- * necessary. Method block
blocks the current thread
+ * Method {@code isReleasable} must return true if blocking is not
+ * necessary. Method {@code block} blocks the current thread
* if necessary (perhaps internally invoking isReleasable before
* actually blocking.).
* maintainParallelism
is true and the pool supports
+ * {@code maintainParallelism} is true and the pool supports
* it ({@link #getMaintainsParallelism}), this method attempts to
* maintain the pool's nominal parallelism. Otherwise if activates
* a thread only if necessary to avoid complete starvation. This
@@ -1659,7 +1759,7 @@ public class ForkJoinPool extends Abstra
* attempt to maintain the pool's nominal parallelism; otherwise
* activate a thread only if necessary to avoid complete
* starvation.
- * @throws InterruptedException if blocker.block did so.
+ * @throws InterruptedException if blocker.block did so
*/
public static void managedBlock(ManagedBlocker blocker,
boolean maintainParallelism)
@@ -1696,8 +1796,36 @@ public class ForkJoinPool extends Abstra
// Temporary Unsafe mechanics for preliminary release
+ private static Unsafe getUnsafe() throws Throwable {
+ try {
+ return Unsafe.getUnsafe();
+ } catch (SecurityException se) {
+ try {
+ return java.security.AccessController.doPrivileged
+ (new java.security.PrivilegedExceptionAction