src/share/classes/java/util/concurrent/ForkJoinPool.java

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*** 33,42 **** --- 33,43 ---- * http://creativecommons.org/publicdomain/zero/1.0/ */ package java.util.concurrent; + import java.lang.Thread.UncaughtExceptionHandler; import java.util.ArrayList; import java.util.Arrays; import java.util.Collection; import java.util.Collections; import java.util.List;
*** 102,143 **** * use the within-computation forms listed in the table unless using * async event-style tasks that are not usually joined, in which case * there is little difference among choice of methods. * * <table BORDER CELLPADDING=3 CELLSPACING=1> * <tr> * <td></td> * <td ALIGN=CENTER> <b>Call from non-fork/join clients</b></td> * <td ALIGN=CENTER> <b>Call from within fork/join computations</b></td> * </tr> * <tr> ! * <td> <b>Arrange async execution</td> * <td> {@link #execute(ForkJoinTask)}</td> * <td> {@link ForkJoinTask#fork}</td> * </tr> * <tr> ! * <td> <b>Await and obtain result</td> * <td> {@link #invoke(ForkJoinTask)}</td> * <td> {@link ForkJoinTask#invoke}</td> * </tr> * <tr> ! * <td> <b>Arrange exec and obtain Future</td> * <td> {@link #submit(ForkJoinTask)}</td> * <td> {@link ForkJoinTask#fork} (ForkJoinTasks <em>are</em> Futures)</td> * </tr> * </table> * * <p>The common pool is by default constructed with default ! * parameters, but these may be controlled by setting three {@link ! * System#getProperty system properties} with prefix {@code ! * java.util.concurrent.ForkJoinPool.common}: {@code parallelism} -- ! * an integer greater than zero, {@code threadFactory} -- the class ! * name of a {@link ForkJoinWorkerThreadFactory}, and {@code ! * exceptionHandler} -- the class name of a {@link ! * java.lang.Thread.UncaughtExceptionHandler ! * Thread.UncaughtExceptionHandler}. Upon any error in establishing ! * these settings, default parameters are used. * * <p><b>Implementation notes</b>: This implementation restricts the * maximum number of running threads to 32767. Attempts to create * pools with greater than the maximum number result in * {@code IllegalArgumentException}. --- 103,148 ---- * use the within-computation forms listed in the table unless using * async event-style tasks that are not usually joined, in which case * there is little difference among choice of methods. * * <table BORDER CELLPADDING=3 CELLSPACING=1> + * <caption>Summary of task execution methods</caption> * <tr> * <td></td> * <td ALIGN=CENTER> <b>Call from non-fork/join clients</b></td> * <td ALIGN=CENTER> <b>Call from within fork/join computations</b></td> * </tr> * <tr> ! * <td> <b>Arrange async execution</b></td> * <td> {@link #execute(ForkJoinTask)}</td> * <td> {@link ForkJoinTask#fork}</td> * </tr> * <tr> ! * <td> <b>Await and obtain result</b></td> * <td> {@link #invoke(ForkJoinTask)}</td> * <td> {@link ForkJoinTask#invoke}</td> * </tr> * <tr> ! * <td> <b>Arrange exec and obtain Future</b></td> * <td> {@link #submit(ForkJoinTask)}</td> * <td> {@link ForkJoinTask#fork} (ForkJoinTasks <em>are</em> Futures)</td> * </tr> * </table> * * <p>The common pool is by default constructed with default ! * parameters, but these may be controlled by setting three ! * {@linkplain System#getProperty system properties} with prefix ! * {@code "java.util.concurrent.ForkJoinPool.common."}: ! * {@code parallelism} -- a non-negative integer, ! * {@code threadFactory} -- the class name of a ! * {@link ForkJoinWorkerThreadFactory}, and ! * {@code exceptionHandler} -- ! * the class name of a {@link UncaughtExceptionHandler}. ! * Upon any error in establishing these settings, default parameters ! * are used. It is possible to disable or limit the use of threads in ! * the common pool by setting the parallelism property to zero, and/or ! * using a factory that may return {@code null}. * * <p><b>Implementation notes</b>: This implementation restricts the * maximum number of running threads to 32767. Attempts to create * pools with greater than the maximum number result in * {@code IllegalArgumentException}.
*** 223,244 **** * WorkQueues are also used in a similar way for tasks submitted * to the pool. We cannot mix these tasks in the same queues used * for work-stealing (this would contaminate lifo/fifo * processing). Instead, we randomly associate submission queues * with submitting threads, using a form of hashing. The ! * ThreadLocal Submitter class contains a value initially used as ! * a hash code for choosing existing queues, but may be randomly ! * repositioned upon contention with other submitters. In ! * essence, submitters act like workers except that they are ! * restricted to executing local tasks that they submitted (or in ! * the case of CountedCompleters, others with the same root task). ! * However, because most shared/external queue operations are more ! * expensive than internal, and because, at steady state, external ! * submitters will compete for CPU with workers, ForkJoinTask.join ! * and related methods disable them from repeatedly helping to ! * process tasks if all workers are active. Insertion of tasks in ! * shared mode requires a lock (mainly to protect in the case of * resizing) but we use only a simple spinlock (using bits in * field qlock), because submitters encountering a busy queue move * on to try or create other queues -- they block only when * creating and registering new queues. * --- 228,249 ---- * WorkQueues are also used in a similar way for tasks submitted * to the pool. We cannot mix these tasks in the same queues used * for work-stealing (this would contaminate lifo/fifo * processing). Instead, we randomly associate submission queues * with submitting threads, using a form of hashing. The ! * ThreadLocalRandom probe value serves as a hash code for ! * choosing existing queues, and may be randomly repositioned upon ! * contention with other submitters. In essence, submitters act ! * like workers except that they are restricted to executing local ! * tasks that they submitted (or in the case of CountedCompleters, ! * others with the same root task). However, because most ! * shared/external queue operations are more expensive than ! * internal, and because, at steady state, external submitters ! * will compete for CPU with workers, ForkJoinTask.join and ! * related methods disable them from repeatedly helping to process ! * tasks if all workers are active. Insertion of tasks in shared ! * mode requires a lock (mainly to protect in the case of * resizing) but we use only a simple spinlock (using bits in * field qlock), because submitters encountering a busy queue move * on to try or create other queues -- they block only when * creating and registering new queues. *
*** 467,477 **** * methods tryCompensate and awaitJoin. * * Common Pool * =========== * ! * The static commonPool always exists after static * initialization. Since it (or any other created pool) need * never be used, we minimize initial construction overhead and * footprint to the setup of about a dozen fields, with no nested * allocation. Most bootstrapping occurs within method * fullExternalPush during the first submission to the pool. --- 472,482 ---- * methods tryCompensate and awaitJoin. * * Common Pool * =========== * ! * The static common Pool always exists after static * initialization. Since it (or any other created pool) need * never be used, we minimize initial construction overhead and * footprint to the setup of about a dozen fields, with no nested * allocation. Most bootstrapping occurs within method * fullExternalPush during the first submission to the pool.
*** 546,555 **** --- 551,561 ---- /** * Returns a new worker thread operating in the given pool. * * @param pool the pool this thread works in * @throws NullPointerException if the pool is null + * @return the new worker thread */ public ForkJoinWorkerThread newThread(ForkJoinPool pool); } /**
*** 562,591 **** return new ForkJoinWorkerThread(pool); } } /** - * Per-thread records for threads that submit to pools. Currently - * holds only pseudo-random seed / index that is used to choose - * submission queues in method externalPush. In the future, this may - * also incorporate a means to implement different task rejection - * and resubmission policies. - * - * Seeds for submitters and workers/workQueues work in basically - * the same way but are initialized and updated using slightly - * different mechanics. Both are initialized using the same - * approach as in class ThreadLocal, where successive values are - * unlikely to collide with previous values. Seeds are then - * randomly modified upon collisions using xorshifts, which - * requires a non-zero seed. - */ - static final class Submitter { - int seed; - Submitter(int s) { seed = s; } - } - - /** * Class for artificial tasks that are used to replace the target * of local joins if they are removed from an interior queue slot * in WorkQueue.tryRemoveAndExec. We don't need the proxy to * actually do anything beyond having a unique identity. */ --- 568,577 ----
*** 735,745 **** /** * Pushes a task. Call only by owner in unshared queues. (The * shared-queue version is embedded in method externalPush.) * * @param task the task. Caller must ensure non-null. ! * @throw RejectedExecutionException if array cannot be resized */ final void push(ForkJoinTask<?> task) { ForkJoinTask<?>[] a; ForkJoinPool p; int s = top, m, n; if ((a = array) != null) { // ignore if queue removed --- 721,731 ---- /** * Pushes a task. Call only by owner in unshared queues. (The * shared-queue version is embedded in method externalPush.) * * @param task the task. Caller must ensure non-null. ! * @throws RejectedExecutionException if array cannot be resized */ final void push(ForkJoinTask<?> task) { ForkJoinTask<?>[] a; ForkJoinPool p; int s = top, m, n; if ((a = array) != null) { // ignore if queue removed
*** 934,944 **** /** * If present, removes from queue and executes the given task, * or any other cancelled task. Returns (true) on any CAS * or consistency check failure so caller can retry. * ! * @return false if no progress can be made, else true; */ final boolean tryRemoveAndExec(ForkJoinTask<?> task) { boolean stat = true, removed = false, empty = true; ForkJoinTask<?>[] a; int m, s, b, n; if ((a = array) != null && (m = a.length - 1) >= 0 && --- 920,930 ---- /** * If present, removes from queue and executes the given task, * or any other cancelled task. Returns (true) on any CAS * or consistency check failure so caller can retry. * ! * @return false if no progress can be made, else true */ final boolean tryRemoveAndExec(ForkJoinTask<?> task) { boolean stat = true, removed = false, empty = true; ForkJoinTask<?>[] a; int m, s, b, n; if ((a = array) != null && (m = a.length - 1) >= 0 &&
*** 979,989 **** return stat; } /** * Polls for and executes the given task or any other task in ! * its CountedCompleter computation */ final boolean pollAndExecCC(ForkJoinTask<?> root) { ForkJoinTask<?>[] a; int b; Object o; outer: while ((b = base) - top < 0 && (a = array) != null) { long j = (((a.length - 1) & b) << ASHIFT) + ABASE; --- 965,975 ---- return stat; } /** * Polls for and executes the given task or any other task in ! * its CountedCompleter computation. */ final boolean pollAndExecCC(ForkJoinTask<?> root) { ForkJoinTask<?>[] a; int b; Object o; outer: while ((b = base) - top < 0 && (a = array) != null) { long j = (((a.length - 1) & b) << ASHIFT) + ABASE;
*** 1053,1077 **** private static final sun.misc.Unsafe U; private static final long QLOCK; private static final int ABASE; private static final int ASHIFT; static { - int s; try { U = sun.misc.Unsafe.getUnsafe(); Class<?> k = WorkQueue.class; Class<?> ak = ForkJoinTask[].class; QLOCK = U.objectFieldOffset (k.getDeclaredField("qlock")); ABASE = U.arrayBaseOffset(ak); ! s = U.arrayIndexScale(ak); } catch (Exception e) { throw new Error(e); } - if ((s & (s-1)) != 0) - throw new Error("data type scale not a power of two"); - ASHIFT = 31 - Integer.numberOfLeadingZeros(s); } } // static fields (initialized in static initializer below) --- 1039,1062 ---- private static final sun.misc.Unsafe U; private static final long QLOCK; private static final int ABASE; private static final int ASHIFT; static { try { U = sun.misc.Unsafe.getUnsafe(); Class<?> k = WorkQueue.class; Class<?> ak = ForkJoinTask[].class; QLOCK = U.objectFieldOffset (k.getDeclaredField("qlock")); ABASE = U.arrayBaseOffset(ak); ! int scale = U.arrayIndexScale(ak); ! if ((scale & (scale - 1)) != 0) ! throw new Error("data type scale not a power of two"); ! ASHIFT = 31 - Integer.numberOfLeadingZeros(scale); } catch (Exception e) { throw new Error(e); } } } // static fields (initialized in static initializer below)
*** 1081,1099 **** */ public static final ForkJoinWorkerThreadFactory defaultForkJoinWorkerThreadFactory; /** - * Per-thread submission bookkeeping. Shared across all pools - * to reduce ThreadLocal pollution and because random motion - * to avoid contention in one pool is likely to hold for others. - * Lazily initialized on first submission (but null-checked - * in other contexts to avoid unnecessary initialization). - */ - static final ThreadLocal<Submitter> submitters; - - /** * Permission required for callers of methods that may start or * kill threads. */ private static final RuntimePermission modifyThreadPermission; --- 1066,1075 ----
*** 1101,1125 **** * Common (static) pool. Non-null for public use unless a static * construction exception, but internal usages null-check on use * to paranoically avoid potential initialization circularities * as well as to simplify generated code. */ ! static final ForkJoinPool commonPool; /** ! * Common pool parallelism. Must equal commonPool.parallelism. */ ! static final int commonPoolParallelism; /** * Sequence number for creating workerNamePrefix. */ private static int poolNumberSequence; /** ! * Return the next sequence number. We don't expect this to ! * ever contend so use simple builtin sync. */ private static final synchronized int nextPoolId() { return ++poolNumberSequence; } --- 1077,1104 ---- * Common (static) pool. Non-null for public use unless a static * construction exception, but internal usages null-check on use * to paranoically avoid potential initialization circularities * as well as to simplify generated code. */ ! static final ForkJoinPool common; /** ! * Common pool parallelism. To allow simpler use and management ! * when common pool threads are disabled, we allow the underlying ! * common.config field to be zero, but in that case still report ! * parallelism as 1 to reflect resulting caller-runs mechanics. */ ! static final int commonParallelism; /** * Sequence number for creating workerNamePrefix. */ private static int poolNumberSequence; /** ! * Returns the next sequence number. We don't expect this to ! * ever contend, so use simple builtin sync. */ private static final synchronized int nextPoolId() { return ++poolNumberSequence; }
*** 1266,1308 **** volatile int plock; // shutdown status and seqLock volatile int indexSeed; // worker/submitter index seed final int config; // mode and parallelism level WorkQueue[] workQueues; // main registry final ForkJoinWorkerThreadFactory factory; ! final Thread.UncaughtExceptionHandler ueh; // per-worker UEH final String workerNamePrefix; // to create worker name string volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17; volatile Object pad18, pad19, pad1a, pad1b; ! /* * Acquires the plock lock to protect worker array and related * updates. This method is called only if an initial CAS on plock ! * fails. This acts as a spinLock for normal cases, but falls back * to builtin monitor to block when (rarely) needed. This would be * a terrible idea for a highly contended lock, but works fine as * a more conservative alternative to a pure spinlock. */ private int acquirePlock() { ! int spins = PL_SPINS, r = 0, ps, nps; for (;;) { if (((ps = plock) & PL_LOCK) == 0 && U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK)) return nps; - else if (r == 0) { // randomize spins if possible - Thread t = Thread.currentThread(); WorkQueue w; Submitter z; - if ((t instanceof ForkJoinWorkerThread) && - (w = ((ForkJoinWorkerThread)t).workQueue) != null) - r = w.seed; - else if ((z = submitters.get()) != null) - r = z.seed; - else - r = 1; - } else if (spins >= 0) { ! r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift ! if (r >= 0) --spins; } else if (U.compareAndSwapInt(this, PLOCK, ps, ps | PL_SIGNAL)) { synchronized (this) { if ((plock & PL_SIGNAL) != 0) { --- 1245,1276 ---- volatile int plock; // shutdown status and seqLock volatile int indexSeed; // worker/submitter index seed final int config; // mode and parallelism level WorkQueue[] workQueues; // main registry final ForkJoinWorkerThreadFactory factory; ! final UncaughtExceptionHandler ueh; // per-worker UEH final String workerNamePrefix; // to create worker name string volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17; volatile Object pad18, pad19, pad1a, pad1b; ! /** * Acquires the plock lock to protect worker array and related * updates. This method is called only if an initial CAS on plock ! * fails. This acts as a spinlock for normal cases, but falls back * to builtin monitor to block when (rarely) needed. This would be * a terrible idea for a highly contended lock, but works fine as * a more conservative alternative to a pure spinlock. */ private int acquirePlock() { ! int spins = PL_SPINS, ps, nps; for (;;) { if (((ps = plock) & PL_LOCK) == 0 && U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK)) return nps; else if (spins >= 0) { ! if (ThreadLocalRandom.nextSecondarySeed() >= 0) --spins; } else if (U.compareAndSwapInt(this, PLOCK, ps, ps | PL_SIGNAL)) { synchronized (this) { if ((plock & PL_SIGNAL) != 0) {
*** 1330,1372 **** plock = ps; synchronized (this) { notifyAll(); } } /** - * Performs secondary initialization, called when plock is zero. - * Creates workQueue array and sets plock to a valid value. The - * lock body must be exception-free (so no try/finally) so we - * optimistically allocate new array outside the lock and throw - * away if (very rarely) not needed. (A similar tactic is used in - * fullExternalPush.) Because the plock seq value can eventually - * wrap around zero, this method harmlessly fails to reinitialize - * if workQueues exists, while still advancing plock. - * - * Additionally tries to create the first worker. - */ - private void initWorkers() { - WorkQueue[] ws, nws; int ps; - int p = config & SMASK; // find power of two table size - int n = (p > 1) ? p - 1 : 1; // ensure at least 2 slots - n |= n >>> 1; n |= n >>> 2; n |= n >>> 4; n |= n >>> 8; n |= n >>> 16; - n = (n + 1) << 1; - if ((ws = workQueues) == null || ws.length == 0) - nws = new WorkQueue[n]; - else - nws = null; - if (((ps = plock) & PL_LOCK) != 0 || - !U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK)) - ps = acquirePlock(); - if (((ws = workQueues) == null || ws.length == 0) && nws != null) - workQueues = nws; - int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN); - if (!U.compareAndSwapInt(this, PLOCK, ps, nps)) - releasePlock(nps); - tryAddWorker(); - } - - /** * Tries to create and start one worker if fewer than target * parallelism level exist. Adjusts counts etc on failure. */ private void tryAddWorker() { long c; int u; --- 1298,1307 ----
*** 1404,1414 **** * * @param wt the worker thread * @return the worker's queue */ final WorkQueue registerWorker(ForkJoinWorkerThread wt) { ! Thread.UncaughtExceptionHandler handler; WorkQueue[] ws; int s, ps; wt.setDaemon(true); if ((handler = ueh) != null) wt.setUncaughtExceptionHandler(handler); do {} while (!U.compareAndSwapInt(this, INDEXSEED, s = indexSeed, s += SEED_INCREMENT) || --- 1339,1349 ---- * * @param wt the worker thread * @return the worker's queue */ final WorkQueue registerWorker(ForkJoinWorkerThread wt) { ! UncaughtExceptionHandler handler; WorkQueue[] ws; int s, ps; wt.setDaemon(true); if ((handler = ueh) != null) wt.setUncaughtExceptionHandler(handler); do {} while (!U.compareAndSwapInt(this, INDEXSEED, s = indexSeed, s += SEED_INCREMENT) ||
*** 1448,1458 **** * Final callback from terminating worker, as well as upon failure * to construct or start a worker. Removes record of worker from * array, and adjusts counts. If pool is shutting down, tries to * complete termination. * ! * @param wt the worker thread or null if construction failed * @param ex the exception causing failure, or null if none */ final void deregisterWorker(ForkJoinWorkerThread wt, Throwable ex) { WorkQueue w = null; if (wt != null && (w = wt.workQueue) != null) { --- 1383,1393 ---- * Final callback from terminating worker, as well as upon failure * to construct or start a worker. Removes record of worker from * array, and adjusts counts. If pool is shutting down, tries to * complete termination. * ! * @param wt the worker thread, or null if construction failed * @param ex the exception causing failure, or null if none */ final void deregisterWorker(ForkJoinWorkerThread wt, Throwable ex) { WorkQueue w = null; if (wt != null && (w = wt.workQueue) != null) {
*** 1487,1497 **** WorkQueue[] ws; WorkQueue v; Thread p; int u, i, e; while ((u = (int)((c = ctl) >>> 32)) < 0 && (e = (int)c) >= 0) { if (e > 0) { // activate or create replacement if ((ws = workQueues) == null || (i = e & SMASK) >= ws.length || ! (v = ws[i]) != null) break; long nc = (((long)(v.nextWait & E_MASK)) | ((long)(u + UAC_UNIT) << 32)); if (v.eventCount != (e | INT_SIGN)) break; --- 1422,1432 ---- WorkQueue[] ws; WorkQueue v; Thread p; int u, i, e; while ((u = (int)((c = ctl) >>> 32)) < 0 && (e = (int)c) >= 0) { if (e > 0) { // activate or create replacement if ((ws = workQueues) == null || (i = e & SMASK) >= ws.length || ! (v = ws[i]) == null) break; long nc = (((long)(v.nextWait & E_MASK)) | ((long)(u + UAC_UNIT) << 32)); if (v.eventCount != (e | INT_SIGN)) break;
*** 1524,1537 **** * method. All others are relayed to fullExternalPush. * * @param task the task. Caller must ensure non-null. */ final void externalPush(ForkJoinTask<?> task) { ! WorkQueue[] ws; WorkQueue q; Submitter z; int m; ForkJoinTask<?>[] a; ! if ((z = submitters.get()) != null && plock > 0 && (ws = workQueues) != null && (m = (ws.length - 1)) >= 0 && ! (q = ws[m & z.seed & SQMASK]) != null && U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock int b = q.base, s = q.top, n, an; if ((a = q.array) != null && (an = a.length) > (n = s + 1 - b)) { int j = (((an - 1) & s) << ASHIFT) + ABASE; U.putOrderedObject(a, j, task); --- 1459,1472 ---- * method. All others are relayed to fullExternalPush. * * @param task the task. Caller must ensure non-null. */ final void externalPush(ForkJoinTask<?> task) { ! WorkQueue[] ws; WorkQueue q; int z, m; ForkJoinTask<?>[] a; ! if ((z = ThreadLocalRandom.getProbe()) != 0 && plock > 0 && (ws = workQueues) != null && (m = (ws.length - 1)) >= 0 && ! (q = ws[m & z & SQMASK]) != null && U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock int b = q.base, s = q.top, n, an; if ((a = q.array) != null && (an = a.length) > (n = s + 1 - b)) { int j = (((an - 1) & s) << ASHIFT) + ABASE; U.putOrderedObject(a, j, task);
*** 1547,1584 **** } /** * Full version of externalPush. This method is called, among * other times, upon the first submission of the first task to the ! * pool, so must perform secondary initialization (via ! * initWorkers). It also detects first submission by an external ! * thread by looking up its ThreadLocal, and creates a new shared ! * queue if the one at index if empty or contended. The plock lock ! * body must be exception-free (so no try/finally) so we ! * optimistically allocate new queues outside the lock and throw ! * them away if (very rarely) not needed. */ private void fullExternalPush(ForkJoinTask<?> task) { ! int r = 0; // random index seed ! for (Submitter z = submitters.get();;) { ! WorkQueue[] ws; WorkQueue q; int ps, m, k; ! if (z == null) { ! if (U.compareAndSwapInt(this, INDEXSEED, r = indexSeed, ! r += SEED_INCREMENT) && r != 0) ! submitters.set(z = new Submitter(r)); } ! else if (r == 0) { // move to a different index ! r = z.seed; ! r ^= r << 13; // same xorshift as WorkQueues ! r ^= r >>> 17; ! z.seed = r ^ (r << 5); ! } ! else if ((ps = plock) < 0) throw new RejectedExecutionException(); else if (ps == 0 || (ws = workQueues) == null || ! (m = ws.length - 1) < 0) ! initWorkers(); else if ((q = ws[k = r & m & SQMASK]) != null) { if (q.qlock == 0 && U.compareAndSwapInt(q, QLOCK, 0, 1)) { ForkJoinTask<?>[] a = q.array; int s = q.top; boolean submitted = false; --- 1482,1533 ---- } /** * Full version of externalPush. This method is called, among * other times, upon the first submission of the first task to the ! * pool, so must perform secondary initialization. It also ! * detects first submission by an external thread by looking up ! * its ThreadLocal, and creates a new shared queue if the one at ! * index if empty or contended. The plock lock body must be ! * exception-free (so no try/finally) so we optimistically ! * allocate new queues outside the lock and throw them away if ! * (very rarely) not needed. ! * ! * Secondary initialization occurs when plock is zero, to create ! * workQueue array and set plock to a valid value. This lock body ! * must also be exception-free. Because the plock seq value can ! * eventually wrap around zero, this method harmlessly fails to ! * reinitialize if workQueues exists, while still advancing plock. */ private void fullExternalPush(ForkJoinTask<?> task) { ! int r; ! if ((r = ThreadLocalRandom.getProbe()) == 0) { ! ThreadLocalRandom.localInit(); ! r = ThreadLocalRandom.getProbe(); } ! for (;;) { ! WorkQueue[] ws; WorkQueue q; int ps, m, k; ! boolean move = false; ! if ((ps = plock) < 0) throw new RejectedExecutionException(); else if (ps == 0 || (ws = workQueues) == null || ! (m = ws.length - 1) < 0) { // initialize workQueues ! int p = config & SMASK; // find power of two table size ! int n = (p > 1) ? p - 1 : 1; // ensure at least 2 slots ! n |= n >>> 1; n |= n >>> 2; n |= n >>> 4; ! n |= n >>> 8; n |= n >>> 16; n = (n + 1) << 1; ! WorkQueue[] nws = ((ws = workQueues) == null || ws.length == 0 ? ! new WorkQueue[n] : null); ! if (((ps = plock) & PL_LOCK) != 0 || ! !U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK)) ! ps = acquirePlock(); ! if (((ws = workQueues) == null || ws.length == 0) && nws != null) ! workQueues = nws; ! int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN); ! if (!U.compareAndSwapInt(this, PLOCK, ps, nps)) ! releasePlock(nps); ! } else if ((q = ws[k = r & m & SQMASK]) != null) { if (q.qlock == 0 && U.compareAndSwapInt(q, QLOCK, 0, 1)) { ForkJoinTask<?>[] a = q.array; int s = q.top; boolean submitted = false;
*** 1596,1606 **** if (submitted) { signalWork(q); return; } } ! r = 0; // move on failure } else if (((ps = plock) & PL_LOCK) == 0) { // create new queue q = new WorkQueue(this, null, SHARED_QUEUE, r); if (((ps = plock) & PL_LOCK) != 0 || !U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK)) --- 1545,1555 ---- if (submitted) { signalWork(q); return; } } ! move = true; // move on failure } else if (((ps = plock) & PL_LOCK) == 0) { // create new queue q = new WorkQueue(this, null, SHARED_QUEUE, r); if (((ps = plock) & PL_LOCK) != 0 || !U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
*** 1610,1620 **** int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN); if (!U.compareAndSwapInt(this, PLOCK, ps, nps)) releasePlock(nps); } else ! r = 0; // try elsewhere while lock held } } // Maintaining ctl counts --- 1559,1571 ---- int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN); if (!U.compareAndSwapInt(this, PLOCK, ps, nps)) releasePlock(nps); } else ! move = true; // move if busy ! if (move) ! r = ThreadLocalRandom.advanceProbe(r); } } // Maintaining ctl counts
*** 1701,1711 **** * * * If already enqueued and none of the above apply, possibly * park awaiting signal, else lingering to help scan and signal. * * * If a non-empty queue discovered or left as a hint, ! * help wake up other workers before return * * @param w the worker (via its WorkQueue) * @return a task or null if none found */ private final ForkJoinTask<?> scan(WorkQueue w) { --- 1652,1662 ---- * * * If already enqueued and none of the above apply, possibly * park awaiting signal, else lingering to help scan and signal. * * * If a non-empty queue discovered or left as a hint, ! * help wake up other workers before return. * * @param w the worker (via its WorkQueue) * @return a task or null if none found */ private final ForkJoinTask<?> scan(WorkQueue w) {
*** 1756,1782 **** if (ctl != c || !U.compareAndSwapLong(this, CTL, c, nc)) w.eventCount = ec; // unmark on CAS failure else if ((int)(c >> AC_SHIFT) == 1 - (config & SMASK)) idleAwaitWork(w, nc, c); } ! else if (w.eventCount < 0 && !tryTerminate(false, false) && ! ctl == c) { // block Thread wt = Thread.currentThread(); Thread.interrupted(); // clear status U.putObject(wt, PARKBLOCKER, this); w.parker = wt; // emulate LockSupport.park if (w.eventCount < 0) // recheck ! U.park(false, 0L); w.parker = null; U.putObject(wt, PARKBLOCKER, null); } } if ((h >= 0 || (h = w.hint) >= 0) && (ws = workQueues) != null && h < ws.length && (q = ws[h]) != null) { // signal others before retry WorkQueue v; Thread p; int u, i, s; ! for (int n = (config & SMASK) >>> 1;;) { int idleCount = (w.eventCount < 0) ? 0 : -1; if (((s = idleCount - q.base + q.top) <= n && (n = s) <= 0) || (u = (int)((c = ctl) >>> 32)) >= 0 || (e = (int)c) <= 0 || m < (i = e & SMASK) || --- 1707,1732 ---- if (ctl != c || !U.compareAndSwapLong(this, CTL, c, nc)) w.eventCount = ec; // unmark on CAS failure else if ((int)(c >> AC_SHIFT) == 1 - (config & SMASK)) idleAwaitWork(w, nc, c); } ! else if (w.eventCount < 0 && ctl == c) { Thread wt = Thread.currentThread(); Thread.interrupted(); // clear status U.putObject(wt, PARKBLOCKER, this); w.parker = wt; // emulate LockSupport.park if (w.eventCount < 0) // recheck ! U.park(false, 0L); // block w.parker = null; U.putObject(wt, PARKBLOCKER, null); } } if ((h >= 0 || (h = w.hint) >= 0) && (ws = workQueues) != null && h < ws.length && (q = ws[h]) != null) { // signal others before retry WorkQueue v; Thread p; int u, i, s; ! for (int n = (config & SMASK) - 1;;) { int idleCount = (w.eventCount < 0) ? 0 : -1; if (((s = idleCount - q.base + q.top) <= n && (n = s) <= 0) || (u = (int)((c = ctl) >>> 32)) >= 0 || (e = (int)c) <= 0 || m < (i = e & SMASK) ||
*** 1812,1822 **** * @param currentCtl the ctl value triggering possible quiescence * @param prevCtl the ctl value to restore if thread is terminated */ private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) { if (w != null && w.eventCount < 0 && ! !tryTerminate(false, false) && (int)prevCtl != 0) { int dc = -(short)(currentCtl >>> TC_SHIFT); long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT; long deadline = System.nanoTime() + parkTime - TIMEOUT_SLOP; Thread wt = Thread.currentThread(); while (ctl == currentCtl) { --- 1762,1773 ---- * @param currentCtl the ctl value triggering possible quiescence * @param prevCtl the ctl value to restore if thread is terminated */ private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) { if (w != null && w.eventCount < 0 && ! !tryTerminate(false, false) && (int)prevCtl != 0 && ! ctl == currentCtl) { int dc = -(short)(currentCtl >>> TC_SHIFT); long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT; long deadline = System.nanoTime() + parkTime - TIMEOUT_SLOP; Thread wt = Thread.currentThread(); while (ctl == currentCtl) {
*** 1830,1839 **** --- 1781,1791 ---- if (ctl != currentCtl) break; if (deadline - System.nanoTime() <= 0L && U.compareAndSwapLong(this, CTL, currentCtl, prevCtl)) { w.eventCount = (w.eventCount + E_SEQ) | E_MASK; + w.hint = -1; w.qlock = -1; // shrink break; } } }
*** 1971,1981 **** * and run tasks within the target's computation. * * @param task the task to join * @param mode if shared, exit upon completing any task * if all workers are active - * */ private int helpComplete(ForkJoinTask<?> task, int mode) { WorkQueue[] ws; WorkQueue q; int m, n, s, u; if (task != null && (ws = workQueues) != null && (m = ws.length - 1) >= 0) { --- 1923,1932 ----
*** 2123,2199 **** } } /** * Returns a (probably) non-empty steal queue, if one is found ! * during a random, then cyclic scan, else null. This method must ! * be retried by caller if, by the time it tries to use the queue, ! * it is empty. * @param r a (random) seed for scanning */ private WorkQueue findNonEmptyStealQueue(int r) { ! for (WorkQueue[] ws;;) { ! int ps = plock, m, n; ! if ((ws = workQueues) == null || (m = ws.length - 1) < 1) ! return null; ! for (int j = (m + 1) << 2; ;) { ! WorkQueue q = ws[(((r + j) << 1) | 1) & m]; ! if (q != null && (n = q.base - q.top) < 0) { ! if (n < -1) ! signalWork(q); return q; } ! else if (--j < 0) { if (plock == ps) return null; - break; } } - } - } /** * Runs tasks until {@code isQuiescent()}. We piggyback on * active count ctl maintenance, but rather than blocking * when tasks cannot be found, we rescan until all others cannot * find tasks either. */ final void helpQuiescePool(WorkQueue w) { for (boolean active = true;;) { ! ForkJoinTask<?> localTask; // exhaust local queue ! while ((localTask = w.nextLocalTask()) != null) ! localTask.doExec(); ! // Similar to loop in scan(), but ignoring submissions ! WorkQueue q = findNonEmptyStealQueue(w.nextSeed()); ! if (q != null) { ! ForkJoinTask<?> t; int b; if (!active) { // re-establish active count - long c; active = true; do {} while (!U.compareAndSwapLong (this, CTL, c = ctl, c + AC_UNIT)); } ! if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) w.runSubtask(t); } ! else { ! long c; ! if (active) { // decrement active count without queuing active = false; - do {} while (!U.compareAndSwapLong - (this, CTL, c = ctl, c -= AC_UNIT)); } ! else ! c = ctl; // re-increment on exit ! if ((int)(c >> AC_SHIFT) + (config & SMASK) == 0) { ! do {} while (!U.compareAndSwapLong ! (this, CTL, c = ctl, c + AC_UNIT)); ! break; } } - } - } /** * Gets and removes a local or stolen task for the given worker. * * @return a task, if available --- 2074,2140 ---- } } /** * Returns a (probably) non-empty steal queue, if one is found ! * during a scan, else null. This method must be retried by ! * caller if, by the time it tries to use the queue, it is empty. * @param r a (random) seed for scanning */ private WorkQueue findNonEmptyStealQueue(int r) { ! for (;;) { ! int ps = plock, m; WorkQueue[] ws; WorkQueue q; ! if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) { ! for (int j = (m + 1) << 2; j >= 0; --j) { ! if ((q = ws[(((r + j) << 1) | 1) & m]) != null && ! q.base - q.top < 0) return q; } ! } if (plock == ps) return null; } } /** * Runs tasks until {@code isQuiescent()}. We piggyback on * active count ctl maintenance, but rather than blocking * when tasks cannot be found, we rescan until all others cannot * find tasks either. */ final void helpQuiescePool(WorkQueue w) { for (boolean active = true;;) { ! long c; WorkQueue q; ForkJoinTask<?> t; int b; ! while ((t = w.nextLocalTask()) != null) { ! if (w.base - w.top < 0) ! signalWork(w); ! t.doExec(); ! } ! if ((q = findNonEmptyStealQueue(w.nextSeed())) != null) { if (!active) { // re-establish active count active = true; do {} while (!U.compareAndSwapLong (this, CTL, c = ctl, c + AC_UNIT)); } ! if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) { ! if (q.base - q.top < 0) ! signalWork(q); w.runSubtask(t); } ! } ! else if (active) { // decrement active count without queuing ! long nc = (c = ctl) - AC_UNIT; ! if ((int)(nc >> AC_SHIFT) + (config & SMASK) == 0) ! return; // bypass decrement-then-increment ! if (U.compareAndSwapLong(this, CTL, c, nc)) active = false; } ! else if ((int)((c = ctl) >> AC_SHIFT) + (config & SMASK) == 0 && ! U.compareAndSwapLong(this, CTL, c, c + AC_UNIT)) ! return; } } /** * Gets and removes a local or stolen task for the given worker. * * @return a task, if available
*** 2203,2216 **** WorkQueue q; int b; if ((t = w.nextLocalTask()) != null) return t; if ((q = findNonEmptyStealQueue(w.nextSeed())) == null) return null; ! if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) return t; } } /** * Returns a cheap heuristic guide for task partitioning when * programmers, frameworks, tools, or languages have little or no * idea about task granularity. In essence by offering this --- 2144,2160 ---- WorkQueue q; int b; if ((t = w.nextLocalTask()) != null) return t; if ((q = findNonEmptyStealQueue(w.nextSeed())) == null) return null; ! if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) { ! if (q.base - q.top < 0) ! signalWork(q); return t; } } + } /** * Returns a cheap heuristic guide for task partitioning when * programmers, frameworks, tools, or languages have little or no * idea about task granularity. In essence by offering this
*** 2233,2243 **** * bottom. In perfect steady state, each thread is at * approximately the same level of computation tree. However, * producing extra tasks amortizes the uncertainty of progress and * diffusion assumptions. * ! * So, users will want to use values larger, but not much larger * than 1 to both smooth over transient shortages and hedge * against uneven progress; as traded off against the cost of * extra task overhead. We leave the user to pick a threshold * value to compare with the results of this call to guide * decisions, but recommend values such as 3. --- 2177,2187 ---- * bottom. In perfect steady state, each thread is at * approximately the same level of computation tree. However, * producing extra tasks amortizes the uncertainty of progress and * diffusion assumptions. * ! * So, users will want to use values larger (but not much larger) * than 1 to both smooth over transient shortages and hedge * against uneven progress; as traded off against the cost of * extra task overhead. We leave the user to pick a threshold * value to compare with the results of this call to guide * decisions, but recommend values such as 3.
*** 2286,2334 **** * if no work and no active workers * @param enable if true, enable shutdown when next possible * @return true if now terminating or terminated */ private boolean tryTerminate(boolean now, boolean enable) { ! if (this == commonPool) // cannot shut down return false; for (long c;;) { if (((c = ctl) & STOP_BIT) != 0) { // already terminating if ((short)(c >>> TC_SHIFT) == -(config & SMASK)) { synchronized (this) { notifyAll(); // signal when 0 workers } } return true; } - if (plock >= 0) { // not yet enabled - int ps; - if (!enable) - return false; - if (((ps = plock) & PL_LOCK) != 0 || - !U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK)) - ps = acquirePlock(); - if (!U.compareAndSwapInt(this, PLOCK, ps, SHUTDOWN)) - releasePlock(SHUTDOWN); - } if (!now) { // check if idle & no tasks ! if ((int)(c >> AC_SHIFT) != -(config & SMASK) || ! hasQueuedSubmissions()) return false; ! // Check for unqueued inactive workers. One pass suffices. ! WorkQueue[] ws = workQueues; WorkQueue w; ! if (ws != null) { ! for (int i = 1; i < ws.length; i += 2) { ! if ((w = ws[i]) != null && w.eventCount >= 0) return false; } } } if (U.compareAndSwapLong(this, CTL, c, c | STOP_BIT)) { for (int pass = 0; pass < 3; ++pass) { ! WorkQueue[] ws = workQueues; ! if (ws != null) { ! WorkQueue w; Thread wt; int n = ws.length; for (int i = 0; i < n; ++i) { if ((w = ws[i]) != null) { w.qlock = -1; if (pass > 0) { --- 2230,2282 ---- * if no work and no active workers * @param enable if true, enable shutdown when next possible * @return true if now terminating or terminated */ private boolean tryTerminate(boolean now, boolean enable) { ! int ps; ! if (this == common) // cannot shut down return false; + if ((ps = plock) >= 0) { // enable by setting plock + if (!enable) + return false; + if ((ps & PL_LOCK) != 0 || + !U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK)) + ps = acquirePlock(); + int nps = ((ps + PL_LOCK) & ~SHUTDOWN) | SHUTDOWN; + if (!U.compareAndSwapInt(this, PLOCK, ps, nps)) + releasePlock(nps); + } for (long c;;) { if (((c = ctl) & STOP_BIT) != 0) { // already terminating if ((short)(c >>> TC_SHIFT) == -(config & SMASK)) { synchronized (this) { notifyAll(); // signal when 0 workers } } return true; } if (!now) { // check if idle & no tasks ! WorkQueue[] ws; WorkQueue w; ! if ((int)(c >> AC_SHIFT) != -(config & SMASK)) return false; ! if ((ws = workQueues) != null) { ! for (int i = 0; i < ws.length; ++i) { ! if ((w = ws[i]) != null) { ! if (!w.isEmpty()) { // signal unprocessed tasks ! signalWork(w); return false; } + if ((i & 1) != 0 && w.eventCount >= 0) + return false; // unqueued inactive worker } } + } + } if (U.compareAndSwapLong(this, CTL, c, c | STOP_BIT)) { for (int pass = 0; pass < 3; ++pass) { ! WorkQueue[] ws; WorkQueue w; Thread wt; ! if ((ws = workQueues) != null) { int n = ws.length; for (int i = 0; i < n; ++i) { if ((w = ws[i]) != null) { w.qlock = -1; if (pass > 0) {
*** 2335,2345 **** w.cancelAll(); if (pass > 1 && (wt = w.owner) != null) { if (!wt.isInterrupted()) { try { wt.interrupt(); ! } catch (SecurityException ignore) { } } U.unpark(wt); } } --- 2283,2293 ---- w.cancelAll(); if (pass > 1 && (wt = w.owner) != null) { if (!wt.isInterrupted()) { try { wt.interrupt(); ! } catch (Throwable ignore) { } } U.unpark(wt); } }
*** 2346,2356 **** } } // Wake up workers parked on event queue int i, e; long cc; Thread p; while ((e = (int)(cc = ctl) & E_MASK) != 0 && ! (i = e & SMASK) < n && (w = ws[i]) != null) { long nc = ((long)(w.nextWait & E_MASK) | ((cc + AC_UNIT) & AC_MASK) | (cc & (TC_MASK|STOP_BIT))); if (w.eventCount == (e | INT_SIGN) && --- 2294,2304 ---- } } // Wake up workers parked on event queue int i, e; long cc; Thread p; while ((e = (int)(cc = ctl) & E_MASK) != 0 && ! (i = e & SMASK) < n && i >= 0 && (w = ws[i]) != null) { long nc = ((long)(w.nextWait & E_MASK) | ((cc + AC_UNIT) & AC_MASK) | (cc & (TC_MASK|STOP_BIT))); if (w.eventCount == (e | INT_SIGN) &&
*** 2372,2401 **** /** * Returns common pool queue for a thread that has submitted at * least one task. */ static WorkQueue commonSubmitterQueue() { ! ForkJoinPool p; WorkQueue[] ws; int m; Submitter z; ! return ((z = submitters.get()) != null && ! (p = commonPool) != null && (ws = p.workQueues) != null && (m = ws.length - 1) >= 0) ? ! ws[m & z.seed & SQMASK] : null; } /** * Tries to pop the given task from submitter's queue in common pool. */ static boolean tryExternalUnpush(ForkJoinTask<?> t) { ! ForkJoinPool p; WorkQueue[] ws; WorkQueue q; Submitter z; ! ForkJoinTask<?>[] a; int m, s; if (t != null && ! (z = submitters.get()) != null && ! (p = commonPool) != null && (ws = p.workQueues) != null && (m = ws.length - 1) >= 0 && ! (q = ws[m & z.seed & SQMASK]) != null && (s = q.top) != q.base && (a = q.array) != null) { long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE; if (U.getObject(a, j) == t && U.compareAndSwapInt(q, QLOCK, 0, 1)) { --- 2320,2349 ---- /** * Returns common pool queue for a thread that has submitted at * least one task. */ static WorkQueue commonSubmitterQueue() { ! ForkJoinPool p; WorkQueue[] ws; int m, z; ! return ((z = ThreadLocalRandom.getProbe()) != 0 && ! (p = common) != null && (ws = p.workQueues) != null && (m = ws.length - 1) >= 0) ? ! ws[m & z & SQMASK] : null; } /** * Tries to pop the given task from submitter's queue in common pool. */ static boolean tryExternalUnpush(ForkJoinTask<?> t) { ! ForkJoinPool p; WorkQueue[] ws; WorkQueue q; ! ForkJoinTask<?>[] a; int m, s, z; if (t != null && ! (z = ThreadLocalRandom.getProbe()) != 0 && ! (p = common) != null && (ws = p.workQueues) != null && (m = ws.length - 1) >= 0 && ! (q = ws[m & z & SQMASK]) != null && (s = q.top) != q.base && (a = q.array) != null) { long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE; if (U.getObject(a, j) == t && U.compareAndSwapInt(q, QLOCK, 0, 1)) {
*** 2443,2453 **** } } if (task != null) task.doExec(); if (root.status < 0 || ! (u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0) break; if (task == null) { helpSignal(root, q.poolIndex); if (root.status >= 0) helpComplete(root, SHARED_QUEUE); --- 2391,2402 ---- } } if (task != null) task.doExec(); if (root.status < 0 || ! (config != 0 && ! ((u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0))) break; if (task == null) { helpSignal(root, q.poolIndex); if (root.status >= 0) helpComplete(root, SHARED_QUEUE);
*** 2461,2478 **** * Tries to help execute or signal availability of the given task * from submitter's queue in common pool. */ static void externalHelpJoin(ForkJoinTask<?> t) { // Some hard-to-avoid overlap with tryExternalUnpush ! ForkJoinPool p; WorkQueue[] ws; WorkQueue q, w; Submitter z; ! ForkJoinTask<?>[] a; int m, s, n; if (t != null && ! (z = submitters.get()) != null && ! (p = commonPool) != null && (ws = p.workQueues) != null && (m = ws.length - 1) >= 0 && ! (q = ws[m & z.seed & SQMASK]) != null && (a = q.array) != null) { int am = a.length - 1; if ((s = q.top) != q.base) { long j = ((am & (s - 1)) << ASHIFT) + ABASE; if (U.getObject(a, j) == t && --- 2410,2427 ---- * Tries to help execute or signal availability of the given task * from submitter's queue in common pool. */ static void externalHelpJoin(ForkJoinTask<?> t) { // Some hard-to-avoid overlap with tryExternalUnpush ! ForkJoinPool p; WorkQueue[] ws; WorkQueue q, w; ! ForkJoinTask<?>[] a; int m, s, n, z; if (t != null && ! (z = ThreadLocalRandom.getProbe()) != 0 && ! (p = common) != null && (ws = p.workQueues) != null && (m = ws.length - 1) >= 0 && ! (q = ws[m & z & SQMASK]) != null && (a = q.array) != null) { int am = a.length - 1; if ((s = q.top) != q.base) { long j = ((am & (s - 1)) << ASHIFT) + ABASE; if (U.getObject(a, j) == t &&
*** 2494,2515 **** p.helpSignal(t, q.poolIndex); } } } - /** - * Restricted version of helpQuiescePool for external callers - */ - static void externalHelpQuiescePool() { - ForkJoinPool p; ForkJoinTask<?> t; WorkQueue q; int b; - if ((p = commonPool) != null && - (q = p.findNonEmptyStealQueue(1)) != null && - (b = q.base) - q.top < 0 && - (t = q.pollAt(b)) != null) - t.doExec(); - } - // Exported methods // Constructors /** --- 2443,2452 ----
*** 2522,2532 **** * the caller is not permitted to modify threads * because it does not hold {@link * java.lang.RuntimePermission}{@code ("modifyThread")} */ public ForkJoinPool() { ! this(Runtime.getRuntime().availableProcessors(), defaultForkJoinWorkerThreadFactory, null, false); } /** * Creates a {@code ForkJoinPool} with the indicated parallelism --- 2459,2469 ---- * the caller is not permitted to modify threads * because it does not hold {@link * java.lang.RuntimePermission}{@code ("modifyThread")} */ public ForkJoinPool() { ! this(Math.min(MAX_CAP, Runtime.getRuntime().availableProcessors()), defaultForkJoinWorkerThreadFactory, null, false); } /** * Creates a {@code ForkJoinPool} with the indicated parallelism
*** 2570,2623 **** * because it does not hold {@link * java.lang.RuntimePermission}{@code ("modifyThread")} */ public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory, ! Thread.UncaughtExceptionHandler handler, boolean asyncMode) { checkPermission(); ! if (factory == null) ! throw new NullPointerException(); if (parallelism <= 0 || parallelism > MAX_CAP) throw new IllegalArgumentException(); ! this.factory = factory; ! this.ueh = handler; ! this.config = parallelism | (asyncMode ? (FIFO_QUEUE << 16) : 0); ! long np = (long)(-parallelism); // offset ctl counts ! this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK); ! int pn = nextPoolId(); ! StringBuilder sb = new StringBuilder("ForkJoinPool-"); ! sb.append(Integer.toString(pn)); ! sb.append("-worker-"); ! this.workerNamePrefix = sb.toString(); } /** ! * Constructor for common pool, suitable only for static initialization. ! * Basically the same as above, but uses smallest possible initial footprint. */ ! ForkJoinPool(int parallelism, long ctl, ForkJoinWorkerThreadFactory factory, ! Thread.UncaughtExceptionHandler handler) { ! this.config = parallelism; ! this.ctl = ctl; this.factory = factory; this.ueh = handler; ! this.workerNamePrefix = "ForkJoinPool.commonPool-worker-"; } /** * Returns the common pool instance. This pool is statically ! * constructed; its run state is unaffected by attempts to ! * {@link #shutdown} or {@link #shutdownNow}. * * @return the common pool instance * @since 1.8 */ public static ForkJoinPool commonPool() { ! // assert commonPool != null : "static init error"; ! return commonPool; } // Execution methods /** --- 2507,2573 ---- * because it does not hold {@link * java.lang.RuntimePermission}{@code ("modifyThread")} */ public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory, ! UncaughtExceptionHandler handler, boolean asyncMode) { + this(checkParallelism(parallelism), + checkFactory(factory), + handler, + asyncMode, + "ForkJoinPool-" + nextPoolId() + "-worker-"); checkPermission(); ! } ! ! private static int checkParallelism(int parallelism) { if (parallelism <= 0 || parallelism > MAX_CAP) throw new IllegalArgumentException(); ! return parallelism; } + private static ForkJoinWorkerThreadFactory checkFactory + (ForkJoinWorkerThreadFactory factory) { + if (factory == null) + throw new NullPointerException(); + return factory; + } + /** ! * Creates a {@code ForkJoinPool} with the given parameters, without ! * any security checks or parameter validation. Invoked directly by ! * makeCommonPool. */ ! private ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory, ! UncaughtExceptionHandler handler, ! boolean asyncMode, ! String workerNamePrefix) { ! this.workerNamePrefix = workerNamePrefix; this.factory = factory; this.ueh = handler; ! this.config = parallelism | (asyncMode ? (FIFO_QUEUE << 16) : 0); ! long np = (long)(-parallelism); // offset ctl counts ! this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK); } /** * Returns the common pool instance. This pool is statically ! * constructed; its run state is unaffected by attempts to {@link ! * #shutdown} or {@link #shutdownNow}. However this pool and any ! * ongoing processing are automatically terminated upon program ! * {@link System#exit}. Any program that relies on asynchronous ! * task processing to complete before program termination should ! * invoke {@code commonPool().}{@link #awaitQuiescence awaitQuiescence}, ! * before exit. * * @return the common pool instance * @since 1.8 */ public static ForkJoinPool commonPool() { ! // assert common != null : "static init error"; ! return common; } // Execution methods /**
*** 2669,2679 **** throw new NullPointerException(); ForkJoinTask<?> job; if (task instanceof ForkJoinTask<?>) // avoid re-wrap job = (ForkJoinTask<?>) task; else ! job = new ForkJoinTask.AdaptedRunnableAction(task); externalPush(job); } /** * Submits a ForkJoinTask for execution. --- 2619,2629 ---- throw new NullPointerException(); ForkJoinTask<?> job; if (task instanceof ForkJoinTask<?>) // avoid re-wrap job = (ForkJoinTask<?>) task; else ! job = new ForkJoinTask.RunnableExecuteAction(task); externalPush(job); } /** * Submits a ForkJoinTask for execution.
*** 2736,2766 **** */ public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) { // In previous versions of this class, this method constructed // a task to run ForkJoinTask.invokeAll, but now external // invocation of multiple tasks is at least as efficient. ! List<ForkJoinTask<T>> fs = new ArrayList<ForkJoinTask<T>>(tasks.size()); ! // Workaround needed because method wasn't declared with ! // wildcards in return type but should have been. ! @SuppressWarnings({"unchecked", "rawtypes"}) ! List<Future<T>> futures = (List<Future<T>>) (List) fs; boolean done = false; try { for (Callable<T> t : tasks) { ForkJoinTask<T> f = new ForkJoinTask.AdaptedCallable<T>(t); externalPush(f); - fs.add(f); } ! for (ForkJoinTask<T> f : fs) ! f.quietlyJoin(); done = true; return futures; } finally { if (!done) ! for (ForkJoinTask<T> f : fs) ! f.cancel(false); } } /** * Returns the factory used for constructing new workers. --- 2686,2712 ---- */ public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) { // In previous versions of this class, this method constructed // a task to run ForkJoinTask.invokeAll, but now external // invocation of multiple tasks is at least as efficient. ! ArrayList<Future<T>> futures = new ArrayList<Future<T>>(tasks.size()); boolean done = false; try { for (Callable<T> t : tasks) { ForkJoinTask<T> f = new ForkJoinTask.AdaptedCallable<T>(t); + futures.add(f); externalPush(f); } ! for (int i = 0, size = futures.size(); i < size; i++) ! ((ForkJoinTask<?>)futures.get(i)).quietlyJoin(); done = true; return futures; } finally { if (!done) ! for (int i = 0, size = futures.size(); i < size; i++) ! futures.get(i).cancel(false); } } /** * Returns the factory used for constructing new workers.
*** 2775,2805 **** * Returns the handler for internal worker threads that terminate * due to unrecoverable errors encountered while executing tasks. * * @return the handler, or {@code null} if none */ ! public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() { return ueh; } /** * Returns the targeted parallelism level of this pool. * * @return the targeted parallelism level of this pool */ public int getParallelism() { ! return config & SMASK; } /** * Returns the targeted parallelism level of the common pool. * * @return the targeted parallelism level of the common pool * @since 1.8 */ public static int getCommonPoolParallelism() { ! return commonPoolParallelism; } /** * Returns the number of worker threads that have started but not * yet terminated. The result returned by this method may differ --- 2721,2752 ---- * Returns the handler for internal worker threads that terminate * due to unrecoverable errors encountered while executing tasks. * * @return the handler, or {@code null} if none */ ! public UncaughtExceptionHandler getUncaughtExceptionHandler() { return ueh; } /** * Returns the targeted parallelism level of this pool. * * @return the targeted parallelism level of this pool */ public int getParallelism() { ! int par = (config & SMASK); ! return (par > 0) ? par : 1; } /** * Returns the targeted parallelism level of the common pool. * * @return the targeted parallelism level of the common pool * @since 1.8 */ public static int getCommonPoolParallelism() { ! return commonParallelism; } /** * Returns the number of worker threads that have started but not * yet terminated. The result returned by this method may differ
*** 3053,3063 **** /** * Possibly initiates an orderly shutdown in which previously * submitted tasks are executed, but no new tasks will be * accepted. Invocation has no effect on execution state if this ! * is the {@link #commonPool}, and 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 --- 3000,3010 ---- /** * Possibly initiates an orderly shutdown in which previously * submitted tasks are executed, but no new tasks will be * accepted. Invocation has no effect on execution state if this ! * is the {@link #commonPool()}, and 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
*** 3071,3081 **** } /** * Possibly attempts to cancel and/or stop all tasks, and reject * all subsequently submitted tasks. Invocation has no effect on ! * execution state if this is the {@link #commonPool}, and no * additional effect if already shut down. Otherwise, tasks that * are in the process of being submitted or executed concurrently * during the course of this method may or may not be * rejected. This method cancels both existing and unexecuted * tasks, in order to permit termination in the presence of task --- 3018,3028 ---- } /** * Possibly attempts to cancel and/or stop all tasks, and reject * all subsequently submitted tasks. Invocation has no effect on ! * execution state if this is the {@link #commonPool()}, and no * additional effect if already shut down. Otherwise, tasks that * are in the process of being submitted or executed concurrently * during the course of this method may or may not be * rejected. This method cancels both existing and unexecuted * tasks, in order to permit termination in the presence of task
*** 3134,3155 **** } /** * Blocks until all tasks have completed execution after a * shutdown request, or the timeout occurs, or the current thread ! * is interrupted, whichever happens first. Note that the {@link ! * #commonPool()} never terminates until program shutdown so ! * this method will always time out. * * @param timeout the maximum time to wait * @param unit the time unit of the timeout argument * @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) throws InterruptedException { long nanos = unit.toNanos(timeout); if (isTerminated()) return true; long startTime = System.nanoTime(); boolean terminated = false; --- 3081,3109 ---- } /** * Blocks until all tasks have completed execution after a * shutdown request, or the timeout occurs, or the current thread ! * is interrupted, whichever happens first. Because the {@link ! * #commonPool()} never terminates until program shutdown, when ! * applied to the common pool, this method is equivalent to {@link ! * #awaitQuiescence(long, TimeUnit)} but always returns {@code false}. * * @param timeout the maximum time to wait * @param unit the time unit of the timeout argument * @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) throws InterruptedException { + if (Thread.interrupted()) + throw new InterruptedException(); + if (this == common) { + awaitQuiescence(timeout, unit); + return false; + } long nanos = unit.toNanos(timeout); if (isTerminated()) return true; long startTime = System.nanoTime(); boolean terminated = false;
*** 3165,3185 **** } return terminated; } /** * Interface for extending managed parallelism for tasks running * in {@link ForkJoinPool}s. * * <p>A {@code ManagedBlocker} provides two methods. Method * {@code isReleasable} must return {@code true} if blocking is * not necessary. Method {@code block} blocks the current thread * if necessary (perhaps internally invoking {@code isReleasable} * before actually blocking). These actions are performed by any ! * thread invoking {@link ForkJoinPool#managedBlock}. The ! * unusual methods in this API accommodate synchronizers that may, ! * but don't usually, block for long periods. Similarly, they * allow more efficient internal handling of cases in which * additional workers may be, but usually are not, needed to * ensure sufficient parallelism. Toward this end, * implementations of method {@code isReleasable} must be amenable * to repeated invocation. --- 3119,3195 ---- } return terminated; } /** + * If called by a ForkJoinTask operating in this pool, equivalent + * in effect to {@link ForkJoinTask#helpQuiesce}. Otherwise, + * waits and/or attempts to assist performing tasks until this + * pool {@link #isQuiescent} or the indicated timeout elapses. + * + * @param timeout the maximum time to wait + * @param unit the time unit of the timeout argument + * @return {@code true} if quiescent; {@code false} if the + * timeout elapsed. + */ + public boolean awaitQuiescence(long timeout, TimeUnit unit) { + long nanos = unit.toNanos(timeout); + ForkJoinWorkerThread wt; + Thread thread = Thread.currentThread(); + if ((thread instanceof ForkJoinWorkerThread) && + (wt = (ForkJoinWorkerThread)thread).pool == this) { + helpQuiescePool(wt.workQueue); + return true; + } + long startTime = System.nanoTime(); + WorkQueue[] ws; + int r = 0, m; + boolean found = true; + while (!isQuiescent() && (ws = workQueues) != null && + (m = ws.length - 1) >= 0) { + if (!found) { + if ((System.nanoTime() - startTime) > nanos) + return false; + Thread.yield(); // cannot block + } + found = false; + for (int j = (m + 1) << 2; j >= 0; --j) { + ForkJoinTask<?> t; WorkQueue q; int b; + if ((q = ws[r++ & m]) != null && (b = q.base) - q.top < 0) { + found = true; + if ((t = q.pollAt(b)) != null) { + if (q.base - q.top < 0) + signalWork(q); + t.doExec(); + } + break; + } + } + } + return true; + } + + /** + * Waits and/or attempts to assist performing tasks indefinitely + * until the {@link #commonPool()} {@link #isQuiescent}. + */ + static void quiesceCommonPool() { + common.awaitQuiescence(Long.MAX_VALUE, TimeUnit.NANOSECONDS); + } + + /** * Interface for extending managed parallelism for tasks running * in {@link ForkJoinPool}s. * * <p>A {@code ManagedBlocker} provides two methods. Method * {@code isReleasable} must return {@code true} if blocking is * not necessary. Method {@code block} blocks the current thread * if necessary (perhaps internally invoking {@code isReleasable} * before actually blocking). These actions are performed by any ! * thread invoking {@link ForkJoinPool#managedBlock(ManagedBlocker)}. ! * The unusual methods in this API accommodate synchronizers that ! * may, but don't usually, block for long periods. Similarly, they * allow more efficient internal handling of cases in which * additional workers may be, but usually are not, needed to * ensure sufficient parallelism. Toward this end, * implementations of method {@code isReleasable} must be amenable * to repeated invocation.
*** 3233,3242 **** --- 3243,3253 ---- */ boolean block() throws InterruptedException; /** * Returns {@code true} if blocking is unnecessary. + * @return {@code true} if blocking is unnecessary */ boolean isReleasable(); } /**
*** 3317,3327 **** private static final long PLOCK; private static final long INDEXSEED; private static final long QLOCK; static { ! int s; // initialize field offsets for CAS etc try { U = sun.misc.Unsafe.getUnsafe(); Class<?> k = ForkJoinPool.class; CTL = U.objectFieldOffset (k.getDeclaredField("ctl")); --- 3328,3338 ---- private static final long PLOCK; private static final long INDEXSEED; private static final long QLOCK; static { ! // initialize field offsets for CAS etc try { U = sun.misc.Unsafe.getUnsafe(); Class<?> k = ForkJoinPool.class; CTL = U.objectFieldOffset (k.getDeclaredField("ctl"));
*** 3337,3392 **** Class<?> wk = WorkQueue.class; QLOCK = U.objectFieldOffset (wk.getDeclaredField("qlock")); Class<?> ak = ForkJoinTask[].class; ABASE = U.arrayBaseOffset(ak); ! s = U.arrayIndexScale(ak); ! ASHIFT = 31 - Integer.numberOfLeadingZeros(s); } catch (Exception e) { throw new Error(e); } - if ((s & (s-1)) != 0) - throw new Error("data type scale not a power of two"); ! submitters = new ThreadLocal<Submitter>(); ! ForkJoinWorkerThreadFactory fac = defaultForkJoinWorkerThreadFactory = new DefaultForkJoinWorkerThreadFactory(); modifyThreadPermission = new RuntimePermission("modifyThread"); ! /* ! * Establish common pool parameters. For extra caution, ! * computations to set up common pool state are here; the ! * constructor just assigns these values to fields. ! */ ! int par = 0; ! Thread.UncaughtExceptionHandler handler = null; ! try { // TBD: limit or report ignored exceptions? String pp = System.getProperty ("java.util.concurrent.ForkJoinPool.common.parallelism"); - String hp = System.getProperty - ("java.util.concurrent.ForkJoinPool.common.exceptionHandler"); String fp = System.getProperty ("java.util.concurrent.ForkJoinPool.common.threadFactory"); if (fp != null) ! fac = ((ForkJoinWorkerThreadFactory)ClassLoader. getSystemClassLoader().loadClass(fp).newInstance()); if (hp != null) ! handler = ((Thread.UncaughtExceptionHandler)ClassLoader. getSystemClassLoader().loadClass(hp).newInstance()); - if (pp != null) - par = Integer.parseInt(pp); } catch (Exception ignore) { } ! if (par <= 0) ! par = Runtime.getRuntime().availableProcessors(); ! if (par > MAX_CAP) ! par = MAX_CAP; ! commonPoolParallelism = par; ! long np = (long)(-par); // precompute initial ctl value ! long ct = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK); ! ! commonPool = new ForkJoinPool(par, ct, fac, handler); } } --- 3348,3407 ---- Class<?> wk = WorkQueue.class; QLOCK = U.objectFieldOffset (wk.getDeclaredField("qlock")); Class<?> ak = ForkJoinTask[].class; ABASE = U.arrayBaseOffset(ak); ! int scale = U.arrayIndexScale(ak); ! if ((scale & (scale - 1)) != 0) ! throw new Error("data type scale not a power of two"); ! ASHIFT = 31 - Integer.numberOfLeadingZeros(scale); } catch (Exception e) { throw new Error(e); } ! defaultForkJoinWorkerThreadFactory = new DefaultForkJoinWorkerThreadFactory(); modifyThreadPermission = new RuntimePermission("modifyThread"); ! common = java.security.AccessController.doPrivileged ! (new java.security.PrivilegedAction<ForkJoinPool>() { ! public ForkJoinPool run() { return makeCommonPool(); }}); ! int par = common.config; // report 1 even if threads disabled ! commonParallelism = par > 0 ? par : 1; ! } ! /** ! * Creates and returns the common pool, respecting user settings ! * specified via system properties. ! */ ! private static ForkJoinPool makeCommonPool() { ! int parallelism = -1; ! ForkJoinWorkerThreadFactory factory ! = defaultForkJoinWorkerThreadFactory; ! UncaughtExceptionHandler handler = null; ! try { // ignore exceptions in accesing/parsing properties String pp = System.getProperty ("java.util.concurrent.ForkJoinPool.common.parallelism"); String fp = System.getProperty ("java.util.concurrent.ForkJoinPool.common.threadFactory"); + String hp = System.getProperty + ("java.util.concurrent.ForkJoinPool.common.exceptionHandler"); + if (pp != null) + parallelism = Integer.parseInt(pp); if (fp != null) ! factory = ((ForkJoinWorkerThreadFactory)ClassLoader. getSystemClassLoader().loadClass(fp).newInstance()); if (hp != null) ! handler = ((UncaughtExceptionHandler)ClassLoader. getSystemClassLoader().loadClass(hp).newInstance()); } catch (Exception ignore) { } ! if (parallelism < 0) ! parallelism = Runtime.getRuntime().availableProcessors(); ! if (parallelism > MAX_CAP) ! parallelism = MAX_CAP; ! return new ForkJoinPool(parallelism, factory, handler, false, ! "ForkJoinPool.commonPool-worker-"); } }