--- jsr166/src/jsr166y/ForkJoinPool.java 2012/11/19 01:04:24 1.145
+++ jsr166/src/jsr166y/ForkJoinPool.java 2012/11/19 18:12:42 1.146
@@ -37,7 +37,7 @@ import java.util.concurrent.TimeUnit;
* ForkJoinPool}s may also be appropriate for use with event-style
* tasks that are never joined.
*
- * A static {@link #commonPool} is available and appropriate for
+ *
A static {@link #commonPool()} is available and appropriate for
* most applications. The common pool is used by any ForkJoinTask that
* is not explicitly submitted to a specified pool. Using the common
* pool normally reduces resource usage (its threads are slowly
@@ -103,8 +103,12 @@ import java.util.concurrent.TimeUnit;
* java.util.concurrent.ForkJoinPool.common}: {@code parallelism} --
* an integer greater than zero, {@code threadFactory} -- the class
* name of a {@link ForkJoinWorkerThreadFactory}, and {@code
+<<<<<<< ForkJoinPool.java
+ * exceptionHandler} -- the class name of a {@code
+=======
* exceptionHandler} -- the class name of a {@link
* java.lang.Thread.UncaughtExceptionHandler
+>>>>>>> 1.111
* Thread.UncaughtExceptionHandler}. Upon any error in establishing
* these settings, default parameters are used.
*
@@ -239,7 +243,7 @@ public class ForkJoinPool extends Abstra
* enable shutdown. When used as a lock, it is normally only very
* briefly held, so is nearly always available after at most a
* brief spin, but we use a monitor-based backup strategy to
- * blocking when needed.
+ * block when needed.
*
* Recording WorkQueues. WorkQueues are recorded in the
* "workQueues" array that is created upon first use and expanded
@@ -248,7 +252,7 @@ public class ForkJoinPool extends Abstra
* by a lock but the array is otherwise concurrently readable, and
* accessed directly. To simplify index-based operations, the
* array size is always a power of two, and all readers must
- * tolerate null slots. Worker queues are at odd indices Shared
+ * tolerate null slots. Worker queues are at odd indices. Shared
* (submission) queues are at even indices, up to a maximum of 64
* slots, to limit growth even if array needs to expand to add
* more workers. Grouping them together in this way simplifies and
@@ -318,14 +322,15 @@ public class ForkJoinPool extends Abstra
* general, pools will be over-signalled. When a submission is
* added or another worker adds a task to a queue that is
* apparently empty, they signal waiting workers (or trigger
- * creation of new ones if fewer than the given parallelism level
- * -- see signalWork). These primary signals are buttressed by
- * signals whenever other threads scan for work or do not have a
- * task to process. On most platforms, signalling (unpark)
- * overhead time is noticeably long, and the time between
- * signalling a thread and it actually making progress can be very
- * noticeably long, so it is worth offloading these delays from
- * critical paths as much as possible.
+ * creation of new ones if fewer than the given parallelism
+ * level). These primary signals are buttressed by signals
+ * whenever other threads scan for work or do not have a task to
+ * process (including the case of leaving a hint to unparked
+ * threads to help signal others upon wakeup). On most platforms,
+ * signalling (unpark) overhead time is noticeably long, and the
+ * time between signalling a thread and it actually making
+ * progress can be very noticeably long, so it is worth offloading
+ * these delays from critical paths as much as possible.
*
* Trimming workers. To release resources after periods of lack of
* use, a worker starting to wait when the pool is quiescent will
@@ -393,12 +398,12 @@ public class ForkJoinPool extends Abstra
* steals, rather than use per-task bookkeeping. This sometimes
* requires a linear scan of workQueues array to locate stealers,
* but often doesn't because stealers leave hints (that may become
- * stale/wrong) of where to locate them. A stealHint is only a
- * hint because a worker might have had multiple steals and the
- * hint records only one of them (usually the most current).
- * Hinting isolates cost to when it is needed, rather than adding
- * to per-task overhead. (2) It is "shallow", ignoring nesting
- * and potentially cyclic mutual steals. (3) It is intentionally
+ * stale/wrong) of where to locate them. It is only a hint
+ * because a worker might have had multiple steals and the hint
+ * records only one of them (usually the most current). Hinting
+ * isolates cost to when it is needed, rather than adding to
+ * per-task overhead. (2) It is "shallow", ignoring nesting and
+ * potentially cyclic mutual steals. (3) It is intentionally
* racy: field currentJoin is updated only while actively joining,
* which means that we miss links in the chain during long-lived
* tasks, GC stalls etc (which is OK since blocking in such cases
@@ -525,9 +530,9 @@ public class ForkJoinPool extends Abstra
* Default ForkJoinWorkerThreadFactory implementation; creates a
* new ForkJoinWorkerThread.
*/
- static class DefaultForkJoinWorkerThreadFactory
+ static final class DefaultForkJoinWorkerThreadFactory
implements ForkJoinWorkerThreadFactory {
- public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
+ public final ForkJoinWorkerThread newThread(ForkJoinPool pool) {
return new ForkJoinWorkerThread(pool);
}
}
@@ -598,10 +603,7 @@ public class ForkJoinPool extends Abstra
* trades off slightly slower average field access for the sake of
* avoiding really bad worst-case access. (Until better JVM
* support is in place, this padding is dependent on transient
- * properties of JVM field layout rules.) We also take care in
- * allocating, sizing and resizing the array. Non-shared queue
- * arrays are initialized by workers before use. Others are
- * allocated on first use.
+ * properties of JVM field layout rules.)
*/
static final class WorkQueue {
/**
@@ -627,10 +629,10 @@ public class ForkJoinPool extends Abstra
int seed; // for random scanning; initialize nonzero
volatile int eventCount; // encoded inactivation count; < 0 if inactive
int nextWait; // encoded record of next event waiter
- final int mode; // lifo, fifo, or shared
- int nsteals; // cumulative number of steals
+ int hint; // steal or signal hint (index)
int poolIndex; // index of this queue in pool (or 0)
- int stealHint; // index of most recent known stealer
+ final int mode; // 0: lifo, > 0: fifo, < 0: shared
+ int nsteals; // number of steals
volatile int qlock; // 1: locked, -1: terminate; else 0
volatile int base; // index of next slot for poll
int top; // index of next slot for push
@@ -640,15 +642,19 @@ public class ForkJoinPool extends Abstra
volatile Thread parker; // == owner during call to park; else null
volatile ForkJoinTask currentJoin; // task being joined in awaitJoin
ForkJoinTask currentSteal; // current non-local task being executed
+
// Heuristic padding to ameliorate unfortunate memory placements
Object p00, p01, p02, p03, p04, p05, p06, p07;
- Object p08, p09, p0a, p0b, p0c, p0d, p0e;
+ Object p08, p09, p0a, p0b, p0c;
- WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode) {
- this.mode = mode;
+ WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode,
+ int seed) {
+ this.array = new ForkJoinTask[WorkQueue.INITIAL_QUEUE_CAPACITY];
this.pool = pool;
this.owner = owner;
- // Place indices in the center of array (that is not yet allocated)
+ this.mode = mode;
+ this.seed = seed;
+ // Place indices in the center of array
base = top = INITIAL_QUEUE_CAPACITY >>> 1;
}
@@ -661,74 +667,75 @@ public class ForkJoinPool extends Abstra
* @throw RejectedExecutionException if array cannot be resized
*/
final void push(ForkJoinTask task) {
- ForkJoinPool p; ForkJoinTask[] a;
- int s = top, n;
- if ((a = array) != null && a.length > (n = s + 1 - base)) {
+ ForkJoinTask[] a; ForkJoinPool p;
+ int s = top, m, n;
+ if ((a = array) != null) { // ignore if queue removed
U.putOrderedObject
- (a, (((a.length - 1) & s) << ASHIFT) + ABASE, task);
- top = s + 1;
- if (n <= 1 && (p = pool) != null)
- p.signalWork(this, 1);
+ (a, (((m = a.length - 1) & s) << ASHIFT) + ABASE, task);
+ if ((n = (top = s + 1) - base) <= 1) {
+ if ((p = pool) != null)
+ p.signalWork(this, 0);
+ }
+ else if (n >= m)
+ growArray();
}
- else
- fullPush(task, true);
}
/**
* Pushes a task if lock is free and array is either big
- * enough or can be resized to be big enough. Note: a
- * specialization of a common fast path of this method is in
- * ForkJoinPool.externalPush. When called from a FJWT queue,
- * this can fail only if the pool has been shut down or
- * an out of memory error.
+ * enough or can be resized to be big enough.
*
* @param task the task. Caller must ensure non-null.
- * @param owned if true, throw RJE on failure
+ * @return true if submitted
*/
- final boolean fullPush(ForkJoinTask task, boolean owned) {
- ForkJoinPool p; ForkJoinTask[] a;
- if (owned) {
- if (qlock < 0) // must be shutting down
- throw new RejectedExecutionException();
- }
- else if (!U.compareAndSwapInt(this, QLOCK, 0, 1))
- return false;
- try {
- int s = top, oldLen, len;
- if ((a = array) == null)
- a = array = new ForkJoinTask[len=INITIAL_QUEUE_CAPACITY];
- else if ((oldLen = a.length) > s + 1 - base)
- len = oldLen;
- else if ((len = oldLen << 1) > MAXIMUM_QUEUE_CAPACITY)
- throw new RejectedExecutionException("Capacity exceeded");
- else {
- int oldMask, b;
- ForkJoinTask[] oldA = a;
- a = array = new ForkJoinTask[len];
- if ((oldMask = oldLen - 1) >= 0 && s - (b = base) > 0) {
- int mask = len - 1;
- do {
- ForkJoinTask x;
- int oldj = ((b & oldMask) << ASHIFT) + ABASE;
- int j = ((b & mask) << ASHIFT) + ABASE;
- x = (ForkJoinTask)
- U.getObjectVolatile(oldA, oldj);
- if (x != null &&
- U.compareAndSwapObject(oldA, oldj, x, null))
- U.putObjectVolatile(a, j, x);
- } while (++b != s);
- }
- }
- U.putOrderedObject
- (a, (((len - 1) & s) << ASHIFT) + ABASE, task);
- top = s + 1;
- } finally {
- if (!owned)
- qlock = 0;
+ final boolean trySharedPush(ForkJoinTask task) {
+ boolean submitted = false;
+ if (qlock == 0 && U.compareAndSwapInt(this, QLOCK, 0, 1)) {
+ ForkJoinTask[] a = array; ForkJoinPool p;
+ int s = top;
+ try {
+ if ((a != null && a.length > s + 1 - base) ||
+ (a = growArray()) != null) { // must presize
+ int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
+ U.putOrderedObject(a, j, task);
+ top = s + 1;
+ submitted = true;
+ }
+ } finally {
+ qlock = 0; // unlock
+ }
+ if (submitted && (p = pool) != null)
+ p.signalWork(this, 0);
+ }
+ return submitted;
+ }
+
+ /**
+ * Initializes or doubles the capacity of array. Call either
+ * by owner or with lock held -- it is OK for base, but not
+ * top, to move while resizings are in progress.
+ */
+ final ForkJoinTask[] growArray() {
+ ForkJoinTask[] oldA = array;
+ int size = oldA != null ? oldA.length << 1 : INITIAL_QUEUE_CAPACITY;
+ if (size > MAXIMUM_QUEUE_CAPACITY)
+ throw new RejectedExecutionException("Queue capacity exceeded");
+ int oldMask, t, b;
+ ForkJoinTask[] a = array = new ForkJoinTask[size];
+ if (oldA != null && (oldMask = oldA.length - 1) >= 0 &&
+ (t = top) - (b = base) > 0) {
+ int mask = size - 1;
+ do {
+ ForkJoinTask x;
+ int oldj = ((b & oldMask) << ASHIFT) + ABASE;
+ int j = ((b & mask) << ASHIFT) + ABASE;
+ x = (ForkJoinTask)U.getObjectVolatile(oldA, oldj);
+ if (x != null &&
+ U.compareAndSwapObject(oldA, oldj, x, null))
+ U.putObjectVolatile(a, j, x);
+ } while (++b != t);
}
- if ((p = pool) != null)
- p.signalWork(this, 1);
- return true;
+ return a;
}
/**
@@ -980,11 +987,7 @@ public class ForkJoinPool extends Abstra
if (t != null) {
(currentSteal = t).doExec();
currentSteal = null;
- if (++nsteals < 0) { // spill on overflow
- ForkJoinPool p;
- if ((p = pool) != null)
- p.collectStealCount(this);
- }
+ ++nsteals;
if (top != base) { // process remaining local tasks
if (mode == 0)
popAndExecAll();
@@ -1057,6 +1060,15 @@ public class ForkJoinPool extends Abstra
}
}
+ // static fields (initialized in static initializer below)
+
+ /**
+ * Creates a new ForkJoinWorkerThread. This factory is used unless
+ * overridden in ForkJoinPool constructors.
+ */
+ public static final ForkJoinWorkerThreadFactory
+ defaultForkJoinWorkerThreadFactory;
+
/**
* Per-thread records for threads that submit to pools. Currently
* holds only pseudo-random seed / index that is used to choose
@@ -1077,18 +1089,14 @@ public class ForkJoinPool extends Abstra
Submitter(int s) { seed = s; }
}
- /** Property prefix for constructing common pool */
- private static final String propPrefix =
- "java.util.concurrent.ForkJoinPool.common.";
-
- // static fields (initialized in static initializer below)
-
/**
- * Creates a new ForkJoinWorkerThread. This factory is used unless
- * overridden in ForkJoinPool constructors.
+ * 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).
*/
- public static final ForkJoinWorkerThreadFactory
- defaultForkJoinWorkerThreadFactory;
+ static final ThreadLocal submitters;
/**
* Common (static) pool. Non-null for public use unless a static
@@ -1105,15 +1113,6 @@ public class ForkJoinPool extends Abstra
private static final RuntimePermission modifyThreadPermission;
/**
- * 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 submitters;
-
- /**
* Common pool parallelism. Must equal commonPool.parallelism.
*/
static final int commonPoolParallelism;
@@ -1248,22 +1247,25 @@ public class ForkJoinPool extends Abstra
static final int FIFO_QUEUE = 1;
static final int SHARED_QUEUE = -1;
+ // bounds for #steps in scan loop -- must be power 2 minus 1
+ private static final int MIN_SCAN = 0x1ff; // cover estimation slop
+ private static final int MAX_SCAN = 0x1ffff; // 4 * max workers
+
// Instance fields
/*
- * Field layout order in this class tends to matter more than one
- * would like. Runtime layout order is only loosely related to
+ * Field layout of this class tends to matter more than one would
+ * like. Runtime layout order is only loosely related to
* declaration order and may differ across JVMs, but the following
* empirically works OK on current JVMs.
*/
volatile long stealCount; // collects worker counts
volatile long ctl; // main pool control
- final int parallelism; // parallelism level
- final int localMode; // per-worker scheduling mode
- volatile int indexSeed; // worker/submitter index seed
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; // factory for new workers
+ final ForkJoinWorkerThreadFactory factory;
final Thread.UncaughtExceptionHandler ueh; // per-worker UEH
final String workerNamePrefix; // to create worker name string
@@ -1283,8 +1285,16 @@ public class ForkJoinPool extends Abstra
if (((ps = plock) & PL_LOCK) == 0 &&
U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK))
return nps;
- else if (r == 0)
- r = ThreadLocalRandom.current().nextInt(); // randomize spins
+ 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)
@@ -1318,49 +1328,97 @@ public class ForkJoinPool extends Abstra
synchronized (this) { notifyAll(); }
}
- // Registering and deregistering workers
+ /**
+ * Tries to create and start a worker; adjusts counts etc on failure
+ */
+ private void addWorker() {
+ ForkJoinWorkerThread wt = null;
+ try {
+ (wt = factory.newThread(this)).start();
+ } catch (Throwable ex) {
+ deregisterWorker(wt, ex); // adjust on failure
+ }
+ }
/**
- * Callback from ForkJoinWorkerThread constructor to establish its
- * poolIndex and record its WorkQueue. To avoid scanning bias due
- * to packing entries in front of the workQueues array, we treat
- * the array as a simple power-of-two hash table using per-thread
- * seed as hash, expanding as needed.
- *
- * @param w the worker's queue
- */
- final void registerWorker(WorkQueue w) {
- int s, ps; // generate a rarely colliding candidate index seed
- do {} while (!U.compareAndSwapInt(this, INDEXSEED,
- s = indexSeed, s += SEED_INCREMENT) ||
- s == 0); // skip 0
+ * 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.
+ */
+ private void initWorkQueuesArray() {
+ WorkQueue[] ws; 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;
+ WorkQueue[] nws = new WorkQueue[(n + 1) << 1];
if (((ps = plock) & PL_LOCK) != 0 ||
!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
ps = acquirePlock();
+ if ((ws = workQueues) == null || ws.length == 0)
+ workQueues = nws;
int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
- try {
- WorkQueue[] ws;
- if (w != null && (ws = workQueues) != null) {
- w.seed = s;
- int n = ws.length, m = n - 1;
- int r = (s << 1) | 1; // use odd-numbered indices
- if (ws[r &= m] != null) { // collision
- int probes = 0; // step by approx half size
- int step = (n <= 4) ? 2 : ((n >>> 1) & EVENMASK) + 2;
- while (ws[r = (r + step) & m] != null) {
- if (++probes >= n) {
- workQueues = ws = Arrays.copyOf(ws, n <<= 1);
- m = n - 1;
- probes = 0;
+ if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
+ releasePlock(nps);
+ long c; int u;
+ if ((u = (int)((c = ctl) >>> 32)) < 0 && (int)c == 0) {
+ long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
+ ((u + UAC_UNIT) & UAC_MASK)) << 32;
+ if (U.compareAndSwapLong(this, CTL, c, nc))
+ addWorker();
+ }
+
+ }
+
+ // Registering and deregistering workers
+
+ /**
+ * Callback from ForkJoinWorkerThread to establish and record its
+ * WorkQueue. To avoid scanning bias due to packing entries in
+ * front of the workQueues array, we treat the array as a simple
+ * power-of-two hash table using per-thread seed as hash,
+ * expanding as needed.
+ *
+ * @param wt the worker thread
+ */
+ final void registerWorker(ForkJoinWorkerThread wt) {
+ if (wt != null && wt.workQueue == null) {
+ int s, ps; // generate a rarely colliding candidate index seed
+ do {} while (!U.compareAndSwapInt(this, INDEXSEED, s = indexSeed,
+ s += SEED_INCREMENT) ||
+ s == 0); // skip 0
+ WorkQueue w = new WorkQueue(this, wt, config >>> 16, s);
+ if (((ps = plock) & PL_LOCK) != 0 ||
+ !U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
+ ps = acquirePlock();
+ int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
+ try {
+ WorkQueue[] ws;
+ if ((ws = workQueues) != null && wt.workQueue == null) {
+ int n = ws.length, m = n - 1;
+ int r = (s << 1) | 1; // use odd-numbered indices
+ if (ws[r &= m] != null) { // collision
+ int probes = 0; // step by approx half size
+ int step = (n <= 4) ? 2 : ((n >>> 1) & EVENMASK) + 2;
+ while (ws[r = (r + step) & m] != null) {
+ if (++probes >= n) {
+ workQueues = ws = Arrays.copyOf(ws, n <<= 1);
+ m = n - 1;
+ probes = 0;
+ }
}
}
+ w.eventCount = w.poolIndex = r; // volatile write orders
+ wt.workQueue = ws[r] = w;
}
- w.eventCount = w.poolIndex = r; // establish before recording
- ws[r] = w;
+ } finally {
+ if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
+ releasePlock(nps);
}
- } finally {
- if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
- releasePlock(nps);
}
}
@@ -1377,8 +1435,10 @@ public class ForkJoinPool extends Abstra
WorkQueue w = null;
if (wt != null && (w = wt.workQueue) != null) {
int ps;
- collectStealCount(w);
w.qlock = -1; // ensure set
+ long ns = w.nsteals, sc; // collect steal count
+ do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
+ sc = stealCount, sc + ns));
if (((ps = plock) & PL_LOCK) != 0 ||
!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
ps = acquirePlock();
@@ -1403,7 +1463,7 @@ public class ForkJoinPool extends Abstra
if (!tryTerminate(false, false) && w != null) {
w.cancelAll(); // cancel remaining tasks
if (w.array != null) // suppress signal if never ran
- signalWork(null, 1); // wake up or create replacement
+ helpSignal(null, 0); // wake up or create replacement
if (ex == null) // help clean refs on way out
ForkJoinTask.helpExpungeStaleExceptions();
}
@@ -1412,23 +1472,6 @@ public class ForkJoinPool extends Abstra
ForkJoinTask.rethrow(ex);
}
- /**
- * Collect worker steal count into total. Called on termination
- * and upon int overflow of local count. (There is a possible race
- * in the latter case vs any caller of getStealCount, which can
- * make its results less accurate than usual.)
- */
- final void collectStealCount(WorkQueue w) {
- if (w != null) {
- long sc;
- int ns = w.nsteals;
- w.nsteals = 0; // handle overflow
- long steals = (ns >= 0) ? ns : 1L + (long)(Integer.MAX_VALUE);
- do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
- sc = stealCount, sc + steals));
- }
- }
-
// Submissions
/**
@@ -1445,14 +1488,13 @@ public class ForkJoinPool extends Abstra
(ws = workQueues) != null && (m = (ws.length - 1)) >= 0 &&
(q = ws[m & z.seed & SQMASK]) != null &&
U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock
- int s = q.top, n;
- if ((a = q.array) != null && a.length > (n = s + 1 - q.base)) {
- U.putObject(a, (long)(((a.length - 1) & s) << ASHIFT) + ABASE,
- task);
+ int b = q.base, s = q.top, n, an;
+ if ((a = q.array) != null && (an = a.length) > (n = s + 1 - b)) {
+ U.putObject(a, (long)(((an - 1) & s) << ASHIFT) + ABASE, task);
q.top = s + 1; // push on to deque
q.qlock = 0;
- if (n <= 1)
- signalWork(q, 1);
+ if (n <= 2)
+ signalWork(q, 0);
return;
}
q.qlock = 0;
@@ -1463,64 +1505,53 @@ public class ForkJoinPool extends Abstra
/**
* 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: creating
- * workQueue array and setting plock to a valid value. 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 lock bodies must be
- * exception-free (so no try/finally) so we optimistically
- * allocate new queues/arrays outside the locks and throw them
- * away if (very rarely) not needed. Note that the plock seq value
- * can eventually wrap around zero, but if so harmlessly fails to
- * reinitialize.
+ * pool, so must perform secondary initialization (via
+ * initWorkQueuesArray). 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
+ * 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) {
- for (Submitter z = null;;) {
- WorkQueue[] ws; WorkQueue q; int ps, m, r, s;
- if ((ps = plock) < 0)
+ int r = 0;
+ 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 ((ws = workQueues) == null || (m = ws.length - 1) < 0) {
- int n = parallelism - 1; n |= n >>> 1; n |= n >>> 2;
- n |= n >>> 4; n |= n >>> 8; n |= n >>> 16;
- WorkQueue[] nws = new WorkQueue[(n + 1) << 1]; // power of two
- if ((ps & PL_LOCK) != 0 ||
+ else if (ps == 0 || (ws = workQueues) == null ||
+ (m = ws.length - 1) < 0)
+ initWorkQueuesArray();
+ else if ((q = ws[k = r & m & SQMASK]) != null) {
+ if (q.trySharedPush(task))
+ return;
+ else
+ r = 0; // move on contention
+ }
+ 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))
ps = acquirePlock();
- if ((ws = workQueues) == null)
- workQueues = nws;
+ if ((ws = workQueues) != null && k < ws.length && ws[k] == null)
+ ws[k] = q;
int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
releasePlock(nps);
}
- else if (z == null && (z = submitters.get()) == null) {
- if (U.compareAndSwapInt(this, INDEXSEED,
- s = indexSeed, s += SEED_INCREMENT) &&
- s != 0) // skip 0
- submitters.set(z = new Submitter(s));
- }
- else {
- int k = (r = z.seed) & m & SQMASK;
- if ((q = ws[k]) == null && (ps & PL_LOCK) == 0) {
- (q = new WorkQueue(this, null, SHARED_QUEUE)).poolIndex = k;
- if (((ps = plock) & PL_LOCK) != 0 ||
- !U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
- ps = acquirePlock();
- WorkQueue w = null;
- if ((ws = workQueues) != null && k < ws.length &&
- (w = ws[k]) == null)
- ws[k] = q;
- else
- q = w;
- int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
- if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
- releasePlock(nps);
- }
- if (q != null && q.qlock == 0 && q.fullPush(task, false))
- return;
- r ^= r << 13; // same xorshift as WorkQueues
- r ^= r >>> 17;
- z.seed = r ^= r << 5; // move to a different index
- }
+ else
+ r = 0; // try elsewhere while lock held
}
}
@@ -1541,10 +1572,11 @@ public class ForkJoinPool extends Abstra
* empty or all workers are active.
*
* @param q if non-null, the queue holding tasks to be signalled
- * @param signals the target number of signals.
+ * @param signals the target number of signals (at least one --
+ * if argument is zero also sets signallee hint if parked).
*/
final void signalWork(WorkQueue q, int signals) {
- long c; int e, u, i; WorkQueue[] ws; WorkQueue w; Thread p;
+ long c; int e, u, i, s; WorkQueue[] ws; WorkQueue w; Thread p;
while ((u = (int)((c = ctl) >>> 32)) < 0) {
if ((e = (int)c) > 0) {
if ((ws = workQueues) != null && ws.length > (i = e & SMASK) &&
@@ -1553,14 +1585,16 @@ public class ForkJoinPool extends Abstra
((long)(u + UAC_UNIT) << 32));
if (U.compareAndSwapLong(this, CTL, c, nc)) {
w.eventCount = (e + E_SEQ) & E_MASK;
- if ((p = w.parker) != null)
+ if ((p = w.parker) != null) {
+ if (q != null && signals == 0)
+ w.hint = q.poolIndex;
U.unpark(p);
+ }
if (--signals <= 0)
break;
}
- else
- signals = 1;
- if ((q != null && q.queueSize() == 0))
+ if (q != null && (s = q.queueSize()) <= signals &&
+ (signals = s) <= 0)
break;
}
else
@@ -1570,21 +1604,7 @@ public class ForkJoinPool extends Abstra
long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
((u + UAC_UNIT) & UAC_MASK)) << 32;
if (U.compareAndSwapLong(this, CTL, c, nc)) {
- ForkJoinWorkerThread wt = null;
- Throwable ex = null;
- boolean started = false;
- try {
- ForkJoinWorkerThreadFactory fac;
- if ((fac = factory) != null &&
- (wt = fac.newThread(this)) != null) {
- wt.start();
- started = true;
- }
- } catch (Throwable rex) {
- ex = rex;
- }
- if (!started)
- deregisterWorker(wt, ex); // adjust counts on failure
+ addWorker();
break;
}
}
@@ -1599,9 +1619,8 @@ public class ForkJoinPool extends Abstra
* Top-level runloop for workers, called by ForkJoinWorkerThread.run.
*/
final void runWorker(WorkQueue w) {
- // initialize queue array in this thread
- w.array = new ForkJoinTask[WorkQueue.INITIAL_QUEUE_CAPACITY];
- do { w.runTask(scan(w)); } while (w.qlock >= 0);
+ if (w != null) // skip on initialization failure
+ do { w.runTask(scan(w)); } while (w.qlock >= 0);
}
/**
@@ -1612,17 +1631,18 @@ public class ForkJoinPool extends Abstra
* contention, or state changes that indicate possible success on
* re-invocation.
*
- * The scan searches for tasks across a random permutation of
- * queues (starting at a random index and stepping by a random
- * relative prime, checking each at least once). The scan
- * terminates upon either finding a non-empty queue, or completing
- * the sweep. If the worker is not inactivated, it takes and
- * returns a task from this queue. Otherwise, if not activated, it
- * signals workers (that may include itself) and returns so caller
- * can retry. Also returns for trtry if the worker array may have
- * changed during an empty scan. On failure to find a task, we
- * take one of the following actions, after which the caller will
- * retry calling this method unless terminated.
+ * The scan searches for tasks across queues (starting at a random
+ * index, and relying on registerWorker to irregularly scatter
+ * them within array to avoid bias), checking each at least twice.
+ * The scan terminates upon either finding a non-empty queue, or
+ * completing the sweep. If the worker is not inactivated, it
+ * takes and returns a task from this queue. Otherwise, if not
+ * activated, it signals workers (that may include itself) and
+ * returns so caller can retry. Also returns for true if the
+ * worker array may have changed during an empty scan. On failure
+ * to find a task, we take one of the following actions, after
+ * which the caller will retry calling this method unless
+ * terminated.
*
* * If pool is terminating, terminate the worker.
*
@@ -1639,53 +1659,58 @@ public class ForkJoinPool extends Abstra
* @return a task or null if none found
*/
private final ForkJoinTask scan(WorkQueue w) {
- WorkQueue[] ws; WorkQueue q; // first update random seed
- int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
- int ps = plock, m; // volatile read order matters
- if ((ws = workQueues) != null && (m = ws.length - 1) > 0) {
- int ec = w.eventCount; // ec is negative if inactive
- int step = (r >>> 16) | 1; // relatively prime
- for (int j = (m + 1) << 2; ; --j, r += step) {
- ForkJoinTask t; ForkJoinTask[] a; int b, n;
- if ((q = ws[r & m]) != null && (b = q.base) - q.top < 0 &&
- (a = q.array) != null) { // probably nonempty
+ WorkQueue[] ws; int m, hint;
+ int ps = plock; // read plock before ws
+ if (w != null && (ws = workQueues) != null && (m = ws.length - 1) >= 0) {
+ int ec = w.eventCount; // ec is negative if inactive
+ int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
+ for (int j = ((m + m + 1) | MIN_SCAN) & MAX_SCAN; ; --j) {
+ WorkQueue q; ForkJoinTask[] a; int b;
+ if ((q = ws[(r + j) & m]) != null && (b = q.base) - q.top < 0 &&
+ (a = q.array) != null) { // probably nonempty
int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
- t = (ForkJoinTask)U.getObjectVolatile(a, i);
+ ForkJoinTask t = (ForkJoinTask)
+ U.getObjectVolatile(a, i);
if (q.base == b && ec >= 0 && t != null &&
U.compareAndSwapObject(a, i, t, null)) {
- if ((n = q.top - (q.base = b + 1)) > 0)
- signalWork(q, n);
- return t; // taken
- }
- if (j < m || (ec < 0 && (ec = w.eventCount) < 0)) {
- if ((n = q.queueSize() - 1) > 0)
- signalWork(q, n);
- break; // let caller retry after signal
+ if ((q.base = b + 1) - q.top < 0)
+ signalWork(q, 0);
+ return t; // taken
+ }
+ else if (ec < 0 || j < m) { // cannot take or cannot rescan
+ w.hint = q.poolIndex; // use hint below
+ break; // let caller retry after signal
+ }
+ }
+ else if (j < 0) { // end of scan; in loop to simplify code
+ long c, sc; int e, ns;
+ if ((ns = w.nsteals) != 0) {
+ if (U.compareAndSwapLong(this, STEALCOUNT,
+ sc = stealCount, sc + ns))
+ w.nsteals = 0; // collect steals
}
- }
- else if (j < 0) { // end of scan
- long c = ctl; int e;
- if (plock != ps) // incomplete sweep
+ else if (plock != ps) // ws may have changed
break;
- if ((e = (int)c) < 0) // pool is terminating
- w.qlock = -1;
- else if (ec >= 0) { // try to enqueue/inactivate
+ else if ((e = (int)(c = ctl)) < 0)
+ w.qlock = -1; // pool is terminating
+ else if (ec >= 0) { // try to enqueue/inactivate
long nc = ((long)ec |
((c - AC_UNIT) & (AC_MASK|TC_MASK)));
- w.nextWait = e;
- w.eventCount = ec | INT_SIGN; // mark as inactive
+ w.nextWait = e; // link and mark inactive
+ w.hint = -1; // use hint if set while parked
+ w.eventCount = ec | INT_SIGN;
if (ctl != c ||
!U.compareAndSwapLong(this, CTL, c, nc))
- w.eventCount = ec; // unmark on CAS failure
- else if ((int)(c >> AC_SHIFT) == 1 - parallelism)
- idleAwaitWork(w, nc, c); // quiescent
+ w.eventCount = ec; // unmark on CAS failure
+ else if ((int)(c >> AC_SHIFT) == 1 - (config & SMASK))
+ idleAwaitWork(w, nc, c);
}
- else if (w.seed >= 0 && w.eventCount < 0) {
+ else if (w.eventCount < 0) { // block
Thread wt = Thread.currentThread();
- Thread.interrupted(); // clear status
+ Thread.interrupted(); // clear status
U.putObject(wt, PARKBLOCKER, this);
- w.parker = wt; // emulate LockSupport.park
- if (w.eventCount < 0) // recheck
+ w.parker = wt; // emulate LockSupport.park
+ if (w.eventCount < 0) // recheck
U.park(false, 0L);
w.parker = null;
U.putObject(wt, PARKBLOCKER, null);
@@ -1693,6 +1718,13 @@ public class ForkJoinPool extends Abstra
break;
}
}
+ if ((hint = w.hint) >= 0) { // help signal
+ WorkQueue[] vs; WorkQueue v; int k;
+ w.hint = -1; // suppress resignal
+ if ((vs = workQueues) != null && hint < vs.length &&
+ (v = vs[hint]) != null && (k = v.base - v.top) < -1)
+ signalWork(v, 1 - k);
+ }
}
return null;
}
@@ -1710,9 +1742,8 @@ public class ForkJoinPool extends Abstra
* @param prevCtl the ctl value to restore if thread is terminated
*/
private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) {
- if (w.eventCount < 0 &&
- (this == commonPool || !tryTerminate(false, false)) &&
- (int)prevCtl != 0) {
+ 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 - 100000L; // 1ms slop
@@ -1731,6 +1762,7 @@ public class ForkJoinPool extends Abstra
U.compareAndSwapLong(this, CTL, currentCtl, prevCtl)) {
w.eventCount = (w.eventCount + E_SEQ) | E_MASK;
w.qlock = -1; // shrink
+ w.hint = -1; // suppress helping
break;
}
}
@@ -1738,23 +1770,23 @@ public class ForkJoinPool extends Abstra
}
/**
- * Scans through queues looking for work while joining a task;
- * if any are present, signals.
+ * Scans through queues looking for work (optionally, while
+ * joining a task); if any are present, signals. May return early
+ * if more signalling is detectably unneeded.
*
- * @param task to return early if done
+ * @param task if non-null, return early if done
* @param origin an index to start scan
*/
final int helpSignal(ForkJoinTask task, int origin) {
- WorkQueue[] ws; WorkQueue q; int m, n, s;
- if (task != null && (ws = workQueues) != null &&
- (m = ws.length - 1) >= 0) {
+ WorkQueue[] ws; WorkQueue q; int m, n, s, u;
+ if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
for (int i = 0; i <= m; ++i) {
- if ((s = task.status) < 0)
+ if (task != null && (s = task.status) < 0)
return s;
if ((q = ws[(i + origin) & m]) != null &&
(n = q.queueSize()) > 0) {
signalWork(q, n);
- if ((int)(ctl >> AC_SHIFT) >= 0)
+ if ((u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0)
break;
}
}
@@ -1793,7 +1825,7 @@ public class ForkJoinPool extends Abstra
}
if ((ws = workQueues) == null || (m = ws.length - 1) <= 0)
break restart; // shutting down
- if ((v = ws[h = (j.stealHint | 1) & m]) == null ||
+ if ((v = ws[h = (j.hint | 1) & m]) == null ||
v.currentSteal != subtask) {
for (int origin = h;;) { // find stealer
if (((h = (h + 2) & m) & 15) == 1 &&
@@ -1801,7 +1833,7 @@ public class ForkJoinPool extends Abstra
continue restart; // occasional staleness check
if ((v = ws[h]) != null &&
v.currentSteal == subtask) {
- j.stealHint = h; // save hint
+ j.hint = h; // save hint
break;
}
if (h == origin)
@@ -1858,7 +1890,7 @@ public class ForkJoinPool extends Abstra
*
*/
private int helpComplete(ForkJoinTask task, int mode) {
- WorkQueue[] ws; WorkQueue q; int m, n, s;
+ WorkQueue[] ws; WorkQueue q; int m, n, s, u;
if (task != null && (ws = workQueues) != null &&
(m = ws.length - 1) >= 0) {
for (int j = 1, origin = j;;) {
@@ -1866,7 +1898,8 @@ public class ForkJoinPool extends Abstra
return s;
if ((q = ws[j & m]) != null && q.pollAndExecCC(task)) {
origin = j;
- if (mode == SHARED_QUEUE && (int)(ctl >> AC_SHIFT) >= 0)
+ if (mode == SHARED_QUEUE &&
+ ((u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0))
break;
}
else if ((j = (j + 2) & m) == origin)
@@ -1884,9 +1917,9 @@ public class ForkJoinPool extends Abstra
* may become starved.
*/
final boolean tryCompensate() {
- int pc = parallelism, e, u, i, tc; long c;
+ int pc = config & SMASK, e, i, tc; long c;
WorkQueue[] ws; WorkQueue w; Thread p;
- if ((e = (int)(c = ctl)) >= 0 && (ws = workQueues) != null) {
+ if ((ws = workQueues) != null && (e = (int)(c = ctl)) >= 0) {
if (e != 0 && (i = e & SMASK) < ws.length &&
(w = ws[i]) != null && w.eventCount == (e | INT_SIGN)) {
long nc = ((long)(w.nextWait & E_MASK) |
@@ -1898,28 +1931,17 @@ public class ForkJoinPool extends Abstra
return true; // replace with idle worker
}
}
- else if ((short)((u = (int)(c >>> 32)) >>> UTC_SHIFT) >= 0 &&
- (u >> UAC_SHIFT) + pc > 1) {
+ else if ((tc = (short)(c >>> TC_SHIFT)) >= 0 &&
+ (int)(c >> AC_SHIFT) + pc > 1) {
long nc = ((c - AC_UNIT) & AC_MASK) | (c & ~AC_MASK);
if (U.compareAndSwapLong(this, CTL, c, nc))
- return true; // no compensation
+ return true; // no compensation
}
- else if ((tc = u + pc) < MAX_CAP) {
+ else if (tc + pc < MAX_CAP) {
long nc = ((c + TC_UNIT) & TC_MASK) | (c & ~TC_MASK);
if (U.compareAndSwapLong(this, CTL, c, nc)) {
- Throwable ex = null;
- ForkJoinWorkerThread wt = null;
- try {
- ForkJoinWorkerThreadFactory fac;
- if ((fac = factory) != null &&
- (wt = fac.newThread(this)) != null) {
- wt.start();
- return true;
- }
- } catch (Throwable rex) {
- ex = rex;
- }
- deregisterWorker(wt, ex); // adjust counts etc
+ addWorker();
+ return true;
}
}
}
@@ -1945,25 +1967,36 @@ public class ForkJoinPool extends Abstra
(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
(task instanceof CountedCompleter))
s = helpComplete(task, LIFO_QUEUE);
+ int k = 0; // to perform pre-block yield for politeness
while (s >= 0 && (s = task.status) >= 0) {
if ((joiner.queueSize() > 0 || // try helping
(s = tryHelpStealer(joiner, task)) == 0) &&
- (s = task.status) >= 0 && tryCompensate()) {
- if (task.trySetSignal() && (s = task.status) >= 0) {
- synchronized (task) {
- if (task.status >= 0) {
- try { // see ForkJoinTask
- task.wait(); // for explanation
- } catch (InterruptedException ie) {
+ (s = task.status) >= 0) {
+ if (k < 3) {
+ if (++k < 3)
+ s = helpSignal(task, joiner.poolIndex);
+ else
+ Thread.yield();
+ }
+ else if (!tryCompensate())
+ k = 0;
+ else {
+ if (task.trySetSignal() && (s = task.status) >= 0) {
+ synchronized (task) {
+ if (task.status >= 0) {
+ try { // see ForkJoinTask
+ task.wait(); // for explanation
+ } catch (InterruptedException ie) {
+ }
}
+ else
+ task.notifyAll();
}
- else
- task.notifyAll();
}
+ long c; // re-activate
+ do {} while (!U.compareAndSwapLong
+ (this, CTL, c = ctl, c + AC_UNIT));
}
- long c; // re-activate
- do {} while (!U.compareAndSwapLong
- (this, CTL, c = ctl, c + AC_UNIT));
}
}
joiner.currentJoin = prevJoin;
@@ -2007,15 +2040,17 @@ public class ForkJoinPool extends Abstra
* @param r a (random) seed for scanning
*/
private WorkQueue findNonEmptyStealQueue(int r) {
- int step = (r >>> 16) | 1;
for (WorkQueue[] ws;;) {
- int ps = plock, m;
+ int ps = plock, m, n;
if ((ws = workQueues) == null || (m = ws.length - 1) < 1)
return null;
- for (int j = (m + 1) << 2; ; r += step) {
- WorkQueue q = ws[((r << 1) | 1) & m];
- if (q != null && q.queueSize() > 0)
+ for (int j = (m + 1) << 2; ;) {
+ WorkQueue q = ws[(((r + j) << 1) | 1) & m];
+ if (q != null && (n = q.queueSize()) > 0) {
+ if (n > 1)
+ signalWork(q, 0);
return q;
+ }
else if (--j < 0) {
if (plock == ps)
return null;
@@ -2058,7 +2093,7 @@ public class ForkJoinPool extends Abstra
}
else
c = ctl; // re-increment on exit
- if ((int)(c >> AC_SHIFT) + parallelism == 0) {
+ if ((int)(c >> AC_SHIFT) + (config & SMASK) == 0) {
do {} while (!U.compareAndSwapLong
(this, CTL, c = ctl, c + AC_UNIT));
break;
@@ -2133,14 +2168,14 @@ public class ForkJoinPool extends Abstra
static int getSurplusQueuedTaskCount() {
Thread t; ForkJoinWorkerThread wt; ForkJoinPool pool; WorkQueue q;
if (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)) {
- int b = (q = (wt = (ForkJoinWorkerThread)t).workQueue).base;
- int p = (pool = wt.pool).parallelism;
+ int p = (pool = (wt = (ForkJoinWorkerThread)t).pool).config & SMASK;
+ int n = (q = wt.workQueue).top - q.base;
int a = (int)(pool.ctl >> AC_SHIFT) + p;
- return q.top - b - (a > (p >>>= 1) ? 0 :
- a > (p >>>= 1) ? 1 :
- a > (p >>>= 1) ? 2 :
- a > (p >>>= 1) ? 4 :
- 8);
+ return n - (a > (p >>>= 1) ? 0 :
+ a > (p >>>= 1) ? 1 :
+ a > (p >>>= 1) ? 2 :
+ a > (p >>>= 1) ? 4 :
+ 8);
}
return 0;
}
@@ -2166,7 +2201,7 @@ public class ForkJoinPool extends Abstra
return false;
for (long c;;) {
if (((c = ctl) & STOP_BIT) != 0) { // already terminating
- if ((short)(c >>> TC_SHIFT) == -parallelism) {
+ if ((short)(c >>> TC_SHIFT) == -(config & SMASK)) {
synchronized (this) {
notifyAll(); // signal when 0 workers
}
@@ -2185,7 +2220,7 @@ public class ForkJoinPool extends Abstra
releasePlock(nps);
}
if (!now) { // check if idle & no tasks
- if ((int)(c >> AC_SHIFT) != -parallelism ||
+ if ((int)(c >> AC_SHIFT) != -(config & SMASK) ||
hasQueuedSubmissions())
return false;
// Check for unqueued inactive workers. One pass suffices.
@@ -2287,7 +2322,7 @@ public class ForkJoinPool extends Abstra
if (q != null && (a = q.array) != null && (m = (a.length - 1)) >= 0 &&
root != null && root.status >= 0) {
for (;;) {
- int s; Object o; CountedCompleter task = null;
+ int s, u; Object o; CountedCompleter task = null;
if ((s = q.top) - q.base > 0) {
long j = ((m & (s - 1)) << ASHIFT) + ABASE;
if ((o = U.getObject(a, j)) != null &&
@@ -2310,7 +2345,8 @@ public class ForkJoinPool extends Abstra
}
if (task != null)
task.doExec();
- if (root.status < 0 || (int)(ctl >> AC_SHIFT) >= 0)
+ if (root.status < 0 ||
+ (u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0)
break;
if (task == null) {
if (helpSignal(root, q.poolIndex) >= 0)
@@ -2329,13 +2365,14 @@ public class ForkJoinPool extends Abstra
// Some hard-to-avoid overlap with tryExternalUnpush
ForkJoinPool p; WorkQueue[] ws; WorkQueue q, w; Submitter z;
ForkJoinTask[] a; int m, s, n; long j;
- if (t != null && t.status >= 0 &&
+ 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) {
+ (a = q.array) != null &&
+ t.status >= 0) {
if ((s = q.top) != q.base &&
U.getObjectVolatile
(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
@@ -2363,9 +2400,8 @@ public class ForkJoinPool extends Abstra
*/
static void externalHelpQuiescePool() {
ForkJoinPool p; ForkJoinTask t; WorkQueue q; int b;
- int r = ThreadLocalRandom.current().nextInt();
if ((p = commonPool) != null &&
- (q = p.findNonEmptyStealQueue(r)) != null &&
+ (q = p.findNonEmptyStealQueue(1)) != null &&
(b = q.base) - q.top < 0 &&
(t = q.pollAt(b)) != null)
t.doExec();
@@ -2442,10 +2478,9 @@ public class ForkJoinPool extends Abstra
throw new NullPointerException();
if (parallelism <= 0 || parallelism > MAX_CAP)
throw new IllegalArgumentException();
- this.parallelism = parallelism;
this.factory = factory;
this.ueh = handler;
- this.localMode = asyncMode ? FIFO_QUEUE : LIFO_QUEUE;
+ 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();
@@ -2462,11 +2497,10 @@ public class ForkJoinPool extends Abstra
ForkJoinPool(int parallelism, long ctl,
ForkJoinWorkerThreadFactory factory,
Thread.UncaughtExceptionHandler handler) {
- this.parallelism = parallelism;
+ this.config = parallelism;
this.ctl = ctl;
this.factory = factory;
this.ueh = handler;
- this.localMode = LIFO_QUEUE;
this.workerNamePrefix = "ForkJoinPool.commonPool-worker-";
}
@@ -2476,7 +2510,8 @@ public class ForkJoinPool extends Abstra
* @return the common pool instance
*/
public static ForkJoinPool commonPool() {
- return commonPool; // cannot be null (if so, a static init error)
+ // assert commonPool != null : "static init error";
+ return commonPool;
}
// Execution methods
@@ -2648,7 +2683,7 @@ public class ForkJoinPool extends Abstra
* @return the targeted parallelism level of this pool
*/
public int getParallelism() {
- return parallelism;
+ return config & SMASK;
}
/**
@@ -2669,7 +2704,7 @@ public class ForkJoinPool extends Abstra
* @return the number of worker threads
*/
public int getPoolSize() {
- return parallelism + (short)(ctl >>> TC_SHIFT);
+ return (config & SMASK) + (short)(ctl >>> TC_SHIFT);
}
/**
@@ -2679,7 +2714,7 @@ public class ForkJoinPool extends Abstra
* @return {@code true} if this pool uses async mode
*/
public boolean getAsyncMode() {
- return localMode != 0;
+ return (config >>> 16) == FIFO_QUEUE;
}
/**
@@ -2710,7 +2745,7 @@ public class ForkJoinPool extends Abstra
* @return the number of active threads
*/
public int getActiveThreadCount() {
- int r = parallelism + (int)(ctl >> AC_SHIFT);
+ int r = (config & SMASK) + (int)(ctl >> AC_SHIFT);
return (r <= 0) ? 0 : r; // suppress momentarily negative values
}
@@ -2726,7 +2761,7 @@ public class ForkJoinPool extends Abstra
* @return {@code true} if all threads are currently idle
*/
public boolean isQuiescent() {
- return (int)(ctl >> AC_SHIFT) + parallelism == 0;
+ return (int)(ctl >> AC_SHIFT) + (config & SMASK) == 0;
}
/**
@@ -2889,7 +2924,7 @@ public class ForkJoinPool extends Abstra
}
}
}
- int pc = parallelism;
+ int pc = (config & SMASK);
int tc = pc + (short)(c >>> TC_SHIFT);
int ac = pc + (int)(c >> AC_SHIFT);
if (ac < 0) // ignore transient negative
@@ -2962,7 +2997,7 @@ public class ForkJoinPool extends Abstra
public boolean isTerminated() {
long c = ctl;
return ((c & STOP_BIT) != 0L &&
- (short)(c >>> TC_SHIFT) == -parallelism);
+ (short)(c >>> TC_SHIFT) == -(config & SMASK));
}
/**
@@ -2981,7 +3016,7 @@ public class ForkJoinPool extends Abstra
public boolean isTerminating() {
long c = ctl;
return ((c & STOP_BIT) != 0L &&
- (short)(c >>> TC_SHIFT) != -parallelism);
+ (short)(c >>> TC_SHIFT) != -(config & SMASK));
}
/**
@@ -3125,14 +3160,15 @@ public class ForkJoinPool extends Abstra
if (t instanceof ForkJoinWorkerThread) {
ForkJoinPool p = ((ForkJoinWorkerThread)t).pool;
while (!blocker.isReleasable()) { // variant of helpSignal
- WorkQueue[] ws; WorkQueue q; int m, n;
+ WorkQueue[] ws; WorkQueue q; int m, n, u;
if ((ws = p.workQueues) != null && (m = ws.length - 1) >= 0) {
for (int i = 0; i <= m; ++i) {
if (blocker.isReleasable())
return;
if ((q = ws[i]) != null && (n = q.queueSize()) > 0) {
p.signalWork(q, n);
- if ((int)(p.ctl >> AC_SHIFT) >= 0)
+ if ((u = (int)(p.ctl >>> 32)) >= 0 ||
+ (u >> UAC_SHIFT) >= 0)
break;
}
}
@@ -3178,27 +3214,6 @@ public class ForkJoinPool extends Abstra
private static final long QLOCK;
static {
- // Establish common pool parameters
- // TBD: limit or report ignored exceptions?
-
- int par = 0;
- ForkJoinWorkerThreadFactory fac = null;
- Thread.UncaughtExceptionHandler handler = null;
- try {
- String pp = System.getProperty(propPrefix + "parallelism");
- String hp = System.getProperty(propPrefix + "exceptionHandler");
- String fp = System.getProperty(propPrefix + "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) {
- }
-
int s; // initialize field offsets for CAS etc
try {
U = getUnsafe();
@@ -3227,26 +3242,45 @@ public class ForkJoinPool extends Abstra
if ((s & (s-1)) != 0)
throw new Error("data type scale not a power of two");
+ submitters = new ThreadLocal();
+ ForkJoinWorkerThreadFactory fac = defaultForkJoinWorkerThreadFactory =
+ new DefaultForkJoinWorkerThreadFactory();
/*
- * For extra caution, computations to set up pool state are
- * here; the constructor just assigns these values to fields.
+ * Establish common pool parameters. For extra caution,
+ * computations to set up common pool state are here; the
+ * constructor just assigns these values to fields.
*/
- ForkJoinWorkerThreadFactory defaultFac =
- defaultForkJoinWorkerThreadFactory =
- new DefaultForkJoinWorkerThreadFactory();
- if (fac == null)
- fac = defaultFac;
+
+ 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);
- commonPoolParallelism = par;
commonPool = new ForkJoinPool(par, ct, fac, handler);
modifyThreadPermission = new RuntimePermission("modifyThread");
- submitters = new ThreadLocal();
}
/**