--- jsr166/src/jsr166y/ForkJoinPool.java 2009/07/20 21:45:06 1.7
+++ jsr166/src/jsr166y/ForkJoinPool.java 2009/07/24 18:57:56 1.19
@@ -28,7 +28,7 @@ import java.lang.reflect.*;
* 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. When setting
- * setAsyncMode, a ForkJoinPools may also be appropriate for
+ * {@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.
@@ -38,24 +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
)
+ * level may also be changed dynamically ({@code setParallelism})
* and thread construction can be limited using methods
- * setMaximumPoolSize
and/or
- * setMaintainsParallelism
.
+ * {@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 {
@@ -81,13 +84,13 @@ 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);
}
/**
- * Default ForkJoinWorkerThreadFactory implementation, creates a
+ * Default ForkJoinWorkerThreadFactory implementation; creates a
* new ForkJoinWorkerThread.
*/
static class DefaultForkJoinWorkerThreadFactory
@@ -153,7 +156,7 @@ public class ForkJoinPool extends Abstra
/**
* The uncaught exception handler used when any worker
- * abrupty terminates
+ * abruptly terminates
*/
private Thread.UncaughtExceptionHandler ueh;
@@ -181,7 +184,7 @@ public class ForkJoinPool extends Abstra
private final LinkedTransferQueue For example, here is a ManagedBlocker based on a
* ReentrantLock:
- * If the caller is not a ForkJoinTask, this method is behaviorally
* equivalent to
- * ("modifyThread")
,
+ * java.lang.RuntimePermission}{@code ("modifyThread")}
*/
public ForkJoinPool() {
this(Runtime.getRuntime().availableProcessors(),
@@ -341,15 +350,16 @@ public class ForkJoinPool extends Abstra
}
/**
- * Creates a ForkJoinPool with the indicated parellelism level
- * threads, and using the default ForkJoinWorkerThreadFactory,
+ * 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
* equal to zero
* @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);
@@ -358,13 +368,14 @@ public class ForkJoinPool extends Abstra
/**
* Creates a ForkJoinPool with parallelism equal to the number of
* processors available on the system and using the given
- * ForkJoinWorkerThreadFactory,
+ * ForkJoinWorkerThreadFactory.
+ *
* @param factory the factory for creating new threads
* @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(ForkJoinWorkerThreadFactory factory) {
this(Runtime.getRuntime().availableProcessors(), factory);
@@ -376,12 +387,12 @@ 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)
@@ -402,7 +413,8 @@ public class ForkJoinPool extends Abstra
}
/**
- * Create new worker using factory.
+ * Creates a new worker thread using factory.
+ *
* @param index the index to assign worker
* @return new worker, or null of factory failed
*/
@@ -421,16 +433,18 @@ public class ForkJoinPool extends Abstra
}
/**
- * Return a good size for worker array given pool size.
+ * Returns a good size for worker array given pool size.
* Currently requires size to be a power of two.
*/
- private static int arraySizeFor(int ps) {
- return ps <= 1? 1 : (1 << (32 - Integer.numberOfLeadingZeros(ps-1)));
+ private static int arraySizeFor(int poolSize) {
+ return (poolSize <= 1) ? 1 :
+ (1 << (32 - Integer.numberOfLeadingZeros(poolSize-1)));
}
/**
- * Create or resize array if necessary to hold newLength.
- * Call only under exlusion or lock
+ * Creates or resizes array if necessary to hold newLength.
+ * Call only under exclusion.
+ *
* @return the array
*/
private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
@@ -444,7 +458,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Try to shrink workers into smaller array after one or more terminate
+ * Tries to shrink workers into smaller array after one or more terminate.
*/
private void tryShrinkWorkerArray() {
ForkJoinWorkerThread[] ws = workers;
@@ -460,7 +474,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Initialize workers if necessary
+ * Initializes workers if necessary.
*/
final void ensureWorkerInitialization() {
ForkJoinWorkerThread[] ws = workers;
@@ -536,7 +550,8 @@ public class ForkJoinPool extends Abstra
}
/**
- * Performs the given task; returning its result upon completion
+ * Performs the given task, returning its result upon completion.
+ *
* @param task the task
* @return the task's result
* @throws NullPointerException if task is null
@@ -549,6 +564,7 @@ public class ForkJoinPool extends Abstra
/**
* Arranges for (asynchronous) execution of the given task.
+ *
* @param task the task
* @throws NullPointerException if task is null
* @throws RejectedExecutionException if pool is shut down
@@ -583,7 +599,7 @@ public class ForkJoinPool extends Abstra
/**
* Adaptor for Runnables. This implements RunnableFuture
- * to be compliant with AbstractExecutorService constraints
+ * to be compliant with AbstractExecutorService constraints.
*/
static final class AdaptedRunnable("modifyThread")
,
+ * java.lang.RuntimePermission}{@code ("modifyThread")}
*/
public Thread.UncaughtExceptionHandler
setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
@@ -716,14 +737,15 @@ 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();
@@ -758,7 +780,7 @@ 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
@@ -770,6 +792,7 @@ public class ForkJoinPool extends Abstra
/**
* Returns the maximum number of threads allowed to exist in the
* pool, even if there are insufficient unblocked running threads.
+ *
* @return the maximum
*/
public int getMaximumPoolSize() {
@@ -781,8 +804,9 @@ public class ForkJoinPool extends Abstra
* pool, even if there are insufficient unblocked running threads.
* 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)
@@ -795,7 +819,8 @@ public class ForkJoinPool extends Abstra
* Returns true if this pool dynamically maintains its target
* parallelism level. If false, new threads are added only to
* avoid possible starvation.
- * This setting is by default true;
+ * This setting is by default true.
+ *
* @return true if maintains parallelism
*/
public boolean getMaintainsParallelism() {
@@ -806,6 +831,7 @@ public class ForkJoinPool extends Abstra
* Sets whether this pool dynamically maintains its target
* parallelism level. If false, new threads are added only to
* avoid possible starvation.
+ *
* @param enable true to maintains parallelism
*/
public void setMaintainsParallelism(boolean enable) {
@@ -819,10 +845,10 @@ public class ForkJoinPool extends Abstra
* 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 ather times may be unpredictable.
+ * invocations at other times may be unpredictable.
*
* @param async if true, use locally FIFO scheduling
- * @return the previous mode.
+ * @return the previous mode
*/
public boolean setAsyncMode(boolean async) {
boolean oldMode = locallyFifo;
@@ -842,7 +868,7 @@ public class ForkJoinPool extends Abstra
* 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.
+ * @return true if this pool uses async mode
*/
public boolean getAsyncMode() {
return locallyFifo;
@@ -863,7 +889,8 @@ 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);
@@ -873,21 +900,23 @@ 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);
- return (c <= 0)? 0 : c;
+ return (c <= 0) ? 0 : c;
}
/**
* Returns true if all worker threads are currently idle. An idle
* worker is one that cannot obtain a task to execute because none
* are available to steal from other threads, and there are no
- * pending submissions to the pool. This method is conservative:
- * It might not return true immediately upon idleness of all
+ * pending submissions to the pool. This method is conservative;
+ * it might not return true immediately upon idleness of all
* threads, but will eventually become true if threads remain
* inactive.
+ *
* @return true if all threads are currently idle
*/
public boolean isQuiescent() {
@@ -899,18 +928,19 @@ public class ForkJoinPool extends Abstra
* one thread's work queue by another. The reported value
* underestimates the actual total number of steals when the pool
* is not quiescent. This value may be useful for monitoring and
- * tuning fork/join programs: In general, steal counts should be
+ * 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();
}
/**
- * Accumulate steal count from a worker. Call only
- * when worker known to be idle.
+ * Accumulates steal count from a worker.
+ * Call only when worker known to be idle.
*/
private void updateStealCount(ForkJoinWorkerThread w) {
int sc = w.getAndClearStealCount();
@@ -925,7 +955,8 @@ 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;
@@ -944,7 +975,8 @@ 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();
@@ -953,7 +985,8 @@ 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();
@@ -963,6 +996,7 @@ public class ForkJoinPool extends Abstra
* Removes and returns the next unexecuted submission if one is
* available. This method may be useful in extensions to this
* class that re-assign work in systems with multiple pools.
+ *
* @return the next submission, or null if none
*/
protected ForkJoinTask> pollSubmission() {
@@ -973,15 +1007,16 @@ 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
- * artifically generated or wrapped tasks. This method id designed
+ * 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 c may result in elements being in
+ * 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
*/
@@ -1042,10 +1077,11 @@ public class ForkJoinPool extends Abstra
* Invocation has no additional effect if already shut down.
* Tasks that are in the process of being submitted concurrently
* during the course of this method may or may not be rejected.
+ *
* @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 shutdown() {
checkPermission();
@@ -1061,13 +1097,14 @@ public class ForkJoinPool extends Abstra
* method may or may not be rejected. Unlike some other executors,
* this method cancels rather than collects non-executed tasks
* upon termination, so always returns an empty list. However, you
- * can use method drainTasksTo
before invoking this
+ * 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;
@@ -1110,8 +1147,8 @@ 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)
@@ -1135,9 +1172,10 @@ public class ForkJoinPool extends Abstra
// Shutdown and termination support
/**
- * Callback from terminating worker. Null out the corresponding
- * workers slot, and if terminating, try to terminate, else try to
- * shrink workers array.
+ * Callback from terminating worker. Nulls out the corresponding
+ * workers slot, and if terminating, tries to terminate; else
+ * tries to shrink workers array.
+ *
* @param w the worker
*/
final void workerTerminated(ForkJoinWorkerThread w) {
@@ -1168,7 +1206,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Initiate termination.
+ * Initiates termination.
*/
private void terminate() {
if (transitionRunStateTo(TERMINATING)) {
@@ -1183,7 +1221,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Possibly terminate when on shutdown state
+ * Possibly terminates when on shutdown state.
*/
private void terminateOnShutdown() {
if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
@@ -1191,7 +1229,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Clear out and cancel submissions
+ * Clears out and cancels submissions.
*/
private void cancelQueuedSubmissions() {
ForkJoinTask> task;
@@ -1200,7 +1238,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Clean out worker queues.
+ * Cleans out worker queues.
*/
private void cancelQueuedWorkerTasks() {
final ReentrantLock lock = this.workerLock;
@@ -1220,8 +1258,8 @@ 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;
@@ -1241,7 +1279,7 @@ 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.
*/
@@ -1311,7 +1349,7 @@ 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;
@@ -1323,7 +1361,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Await release on sync
+ * Awaits release on sync.
*/
void awaitSyncRelease(ForkJoinPool p) {
while (thread != null && !p.syncIsReleasable(this))
@@ -1331,7 +1369,7 @@ public class ForkJoinPool extends Abstra
}
/**
- * Await resumption as spare
+ * Awaits resumption as spare.
*/
void awaitSpareRelease() {
while (thread != null) {
@@ -1345,6 +1383,7 @@ public class ForkJoinPool extends Abstra
* Ensures that no thread is waiting for count to advance from the
* current value of eventCount read on entry to this method, by
* releasing waiting threads if necessary.
+ *
* @return the count
*/
final long ensureSync() {
@@ -1366,12 +1405,12 @@ public class ForkJoinPool extends Abstra
*/
private void signalIdleWorkers() {
long c;
- do;while (!casEventCount(c = eventCount, c+1));
+ do {} while (!casEventCount(c = eventCount, c+1));
ensureSync();
}
/**
- * 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).
@@ -1390,6 +1429,7 @@ public class ForkJoinPool extends Abstra
* Waits until event count advances from last value held by
* caller, or if excess threads, caller is resumed as spare, or
* caller or pool is terminating. Updates caller's event on exit.
+ *
* @param w the calling worker thread
*/
final void sync(ForkJoinWorkerThread w) {
@@ -1420,10 +1460,11 @@ public class ForkJoinPool extends Abstra
* Returns true if worker waiting on sync can proceed:
* - on signal (thread == null)
* - on event count advance (winning race to notify vs signaller)
- * - on Interrupt
+ * - on interrupt
* - 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
*/
final boolean syncIsReleasable(WaitQueueNode node) {
@@ -1458,13 +1499,13 @@ 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
* suspend it later when unblocked -- see suspendIfSpare).
* However, implementing this idea requires coping with
- * several problems: We have imperfect information about the
+ * several problems: we have imperfect information about the
* states of threads. Some count updates can and usually do
* lag run state changes, despite arrangements to keep them
* accurate (for example, when possible, updating counts
@@ -1478,7 +1519,7 @@ 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.
*
@@ -1487,12 +1528,14 @@ public class ForkJoinPool extends Abstra
* target counts, else create only to avoid starvation
* @return true if joinMe known to be done
*/
- final boolean preJoin(ForkJoinTask> joinMe, boolean maintainParallelism) {
+ final boolean preJoin(ForkJoinTask> joinMe,
+ boolean maintainParallelism) {
maintainParallelism &= maintainsParallelism; // overrride
boolean dec = false; // true when running count decremented
while (spareStack == null || !tryResumeSpare(dec)) {
int counts = workerCounts;
- if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat
+ if (dec || (dec = casWorkerCounts(counts, --counts))) {
+ // CAS cheat
if (!needSpare(counts, maintainParallelism))
break;
if (joinMe.status < 0)
@@ -1507,7 +1550,8 @@ public class ForkJoinPool extends Abstra
/**
* Same idea as preJoin
*/
- final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){
+ final boolean preBlock(ManagedBlocker blocker,
+ boolean maintainParallelism) {
maintainParallelism &= maintainsParallelism;
boolean dec = false;
while (spareStack == null || !tryResumeSpare(dec)) {
@@ -1531,6 +1575,7 @@ public class ForkJoinPool extends Abstra
* there is apparently some work to do. This self-limiting rule
* means that the more threads that have already been added, the
* less parallelism we will tolerate before adding another.
+ *
* @param counts current worker counts
* @param maintainParallelism try to maintain parallelism
*/
@@ -1548,8 +1593,9 @@ public class ForkJoinPool extends Abstra
}
/**
- * 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) {
@@ -1582,7 +1628,7 @@ 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) {
@@ -1604,11 +1650,12 @@ 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) {
@@ -1619,7 +1666,7 @@ public class ForkJoinPool extends Abstra
node = new WaitQueueNode(0, w);
if (casWorkerCounts(s, s-1)) { // representation-dependent
// push onto stack
- do;while (!casSpareStack(node.next = spareStack, node));
+ do {} while (!casSpareStack(node.next = spareStack, node));
// block until released by resumeSpare
node.awaitSpareRelease();
return true;
@@ -1629,7 +1676,8 @@ 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
*/
@@ -1647,7 +1695,8 @@ 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() {
@@ -1665,7 +1714,7 @@ 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.
@@ -1690,36 +1739,37 @@ 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
- * if necessary (perhaps internally invoking isReleasable before
- * actually blocking.).
+ * Method {@code isReleasable} must return true if blocking is not
+ * necessary. Method {@code block} blocks the current thread if
+ * necessary (perhaps internally invoking {@code isReleasable}
+ * before actually blocking.).
+ *
*
- * class ManagedLocker implements ManagedBlocker {
- * final ReentrantLock lock;
- * boolean hasLock = false;
- * ManagedLocker(ReentrantLock lock) { this.lock = lock; }
- * public boolean block() {
- * if (!hasLock)
- * lock.lock();
- * return true;
- * }
- * public boolean isReleasable() {
- * return hasLock || (hasLock = lock.tryLock());
- * }
+ *
*/
public static interface ManagedBlocker {
/**
* 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;
@@ -1734,20 +1784,20 @@ 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
- * {@code
+ * class ManagedLocker implements ManagedBlocker {
+ * final ReentrantLock lock;
+ * boolean hasLock = false;
+ * ManagedLocker(ReentrantLock lock) { this.lock = lock; }
+ * public boolean block() {
+ * if (!hasLock)
+ * lock.lock();
+ * return true;
* }
- *
+ * public boolean isReleasable() {
+ * return hasLock || (hasLock = lock.tryLock());
+ * }
+ * }}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
+ * maintain the pool's nominal parallelism. Otherwise it activates
* a thread only if necessary to avoid complete starvation. This
* option may be preferable when blockages use timeouts, or are
* almost always brief.
*
*
- * while (!blocker.isReleasable())
- * if (blocker.block())
- * return;
- *
+ * {@code
+ * while (!blocker.isReleasable())
+ * if (blocker.block())
+ * return;
+ * }
* If the caller is a ForkJoinTask, then the pool may first
* be expanded to ensure parallelism, and later adjusted.
*
@@ -1756,14 +1806,14 @@ 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)
throws InterruptedException {
Thread t = Thread.currentThread();
- ForkJoinPool pool = (t instanceof ForkJoinWorkerThread?
- ((ForkJoinWorkerThread)t).pool : null);
+ ForkJoinPool pool = ((t instanceof ForkJoinWorkerThread) ?
+ ((ForkJoinWorkerThread) t).pool : null);
if (!blocker.isReleasable()) {
try {
if (pool == null ||
@@ -1778,17 +1828,17 @@ public class ForkJoinPool extends Abstra
private static void awaitBlocker(ManagedBlocker blocker)
throws InterruptedException {
- do;while (!blocker.isReleasable() && !blocker.block());
+ do {} while (!blocker.isReleasable() && !blocker.block());
}
// AbstractExecutorService overrides
protected