1 /* ---------------------------------------------------------------------------
3 * (c) The GHC Team, 1998-2006
5 * The scheduler and thread-related functionality
7 * --------------------------------------------------------------------------*/
9 #include "PosixSource.h"
10 #define KEEP_LOCKCLOSURE
15 #include "OSThreads.h"
20 #include "StgMiscClosures.h"
21 #include "Interpreter.h"
23 #include "RtsSignals.h"
29 #include "ThreadLabels.h"
30 #include "LdvProfile.h"
32 #include "Proftimer.h"
35 /* PARALLEL_HASKELL includes go here */
38 #include "Capability.h"
40 #include "AwaitEvent.h"
41 #if defined(mingw32_HOST_OS)
42 #include "win32/IOManager.h"
45 #include "RaiseAsync.h"
47 #include "ThrIOManager.h"
49 #ifdef HAVE_SYS_TYPES_H
50 #include <sys/types.h>
64 // Turn off inlining when debugging - it obfuscates things
67 # define STATIC_INLINE static
70 /* -----------------------------------------------------------------------------
72 * -------------------------------------------------------------------------- */
74 #if !defined(THREADED_RTS)
75 // Blocked/sleeping thrads
76 StgTSO *blocked_queue_hd = NULL;
77 StgTSO *blocked_queue_tl = NULL;
78 StgTSO *sleeping_queue = NULL; // perhaps replace with a hash table?
81 /* Threads blocked on blackholes.
82 * LOCK: sched_mutex+capability, or all capabilities
84 StgTSO *blackhole_queue = NULL;
86 /* The blackhole_queue should be checked for threads to wake up. See
87 * Schedule.h for more thorough comment.
88 * LOCK: none (doesn't matter if we miss an update)
90 rtsBool blackholes_need_checking = rtsFalse;
92 /* flag that tracks whether we have done any execution in this time slice.
93 * LOCK: currently none, perhaps we should lock (but needs to be
94 * updated in the fast path of the scheduler).
96 nat recent_activity = ACTIVITY_YES;
98 /* if this flag is set as well, give up execution
99 * LOCK: none (changes once, from false->true)
101 rtsBool sched_state = SCHED_RUNNING;
103 /* This is used in `TSO.h' and gcc 2.96 insists that this variable actually
104 * exists - earlier gccs apparently didn't.
110 * Set to TRUE when entering a shutdown state (via shutdownHaskellAndExit()) --
111 * in an MT setting, needed to signal that a worker thread shouldn't hang around
112 * in the scheduler when it is out of work.
114 rtsBool shutting_down_scheduler = rtsFalse;
117 * This mutex protects most of the global scheduler data in
118 * the THREADED_RTS runtime.
120 #if defined(THREADED_RTS)
124 #if !defined(mingw32_HOST_OS)
125 #define FORKPROCESS_PRIMOP_SUPPORTED
128 /* -----------------------------------------------------------------------------
129 * static function prototypes
130 * -------------------------------------------------------------------------- */
132 static Capability *schedule (Capability *initialCapability, Task *task);
135 // These function all encapsulate parts of the scheduler loop, and are
136 // abstracted only to make the structure and control flow of the
137 // scheduler clearer.
139 static void schedulePreLoop (void);
140 static void scheduleFindWork (Capability *cap);
141 #if defined(THREADED_RTS)
142 static void scheduleYield (Capability **pcap, Task *task);
144 static void scheduleStartSignalHandlers (Capability *cap);
145 static void scheduleCheckBlockedThreads (Capability *cap);
146 static void scheduleCheckWakeupThreads(Capability *cap USED_IF_NOT_THREADS);
147 static void scheduleCheckBlackHoles (Capability *cap);
148 static void scheduleDetectDeadlock (Capability *cap, Task *task);
149 static void schedulePushWork(Capability *cap, Task *task);
150 #if defined(PARALLEL_HASKELL)
151 static rtsBool scheduleGetRemoteWork(Capability *cap);
152 static void scheduleSendPendingMessages(void);
154 #if defined(PARALLEL_HASKELL) || defined(THREADED_RTS)
155 static void scheduleActivateSpark(Capability *cap);
157 static void schedulePostRunThread(Capability *cap, StgTSO *t);
158 static rtsBool scheduleHandleHeapOverflow( Capability *cap, StgTSO *t );
159 static void scheduleHandleStackOverflow( Capability *cap, Task *task,
161 static rtsBool scheduleHandleYield( Capability *cap, StgTSO *t,
162 nat prev_what_next );
163 static void scheduleHandleThreadBlocked( StgTSO *t );
164 static rtsBool scheduleHandleThreadFinished( Capability *cap, Task *task,
166 static rtsBool scheduleNeedHeapProfile(rtsBool ready_to_gc);
167 static Capability *scheduleDoGC(Capability *cap, Task *task,
168 rtsBool force_major);
170 static rtsBool checkBlackHoles(Capability *cap);
172 static StgTSO *threadStackOverflow(Capability *cap, StgTSO *tso);
173 static StgTSO *threadStackUnderflow(Task *task, StgTSO *tso);
175 static void deleteThread (Capability *cap, StgTSO *tso);
176 static void deleteAllThreads (Capability *cap);
178 #ifdef FORKPROCESS_PRIMOP_SUPPORTED
179 static void deleteThread_(Capability *cap, StgTSO *tso);
183 static char *whatNext_strs[] = {
193 /* -----------------------------------------------------------------------------
194 * Putting a thread on the run queue: different scheduling policies
195 * -------------------------------------------------------------------------- */
198 addToRunQueue( Capability *cap, StgTSO *t )
200 #if defined(PARALLEL_HASKELL)
201 if (RtsFlags.ParFlags.doFairScheduling) {
202 // this does round-robin scheduling; good for concurrency
203 appendToRunQueue(cap,t);
205 // this does unfair scheduling; good for parallelism
206 pushOnRunQueue(cap,t);
209 // this does round-robin scheduling; good for concurrency
210 appendToRunQueue(cap,t);
214 /* ---------------------------------------------------------------------------
215 Main scheduling loop.
217 We use round-robin scheduling, each thread returning to the
218 scheduler loop when one of these conditions is detected:
221 * timer expires (thread yields)
227 In a GranSim setup this loop iterates over the global event queue.
228 This revolves around the global event queue, which determines what
229 to do next. Therefore, it's more complicated than either the
230 concurrent or the parallel (GUM) setup.
231 This version has been entirely removed (JB 2008/08).
234 GUM iterates over incoming messages.
235 It starts with nothing to do (thus CurrentTSO == END_TSO_QUEUE),
236 and sends out a fish whenever it has nothing to do; in-between
237 doing the actual reductions (shared code below) it processes the
238 incoming messages and deals with delayed operations
239 (see PendingFetches).
240 This is not the ugliest code you could imagine, but it's bloody close.
242 (JB 2008/08) This version was formerly indicated by a PP-Flag PAR,
243 now by PP-flag PARALLEL_HASKELL. The Eden RTS (in GHC-6.x) uses it,
244 as well as future GUM versions. This file has been refurbished to
245 only contain valid code, which is however incomplete, refers to
246 invalid includes etc.
248 ------------------------------------------------------------------------ */
251 schedule (Capability *initialCapability, Task *task)
255 StgThreadReturnCode ret;
256 #if defined(PARALLEL_HASKELL)
257 rtsBool receivedFinish = rtsFalse;
261 #if defined(THREADED_RTS)
262 rtsBool first = rtsTrue;
265 cap = initialCapability;
267 // Pre-condition: this task owns initialCapability.
268 // The sched_mutex is *NOT* held
269 // NB. on return, we still hold a capability.
271 debugTrace (DEBUG_sched,
272 "### NEW SCHEDULER LOOP (task: %p, cap: %p)",
273 task, initialCapability);
277 // -----------------------------------------------------------
278 // Scheduler loop starts here:
280 #if defined(PARALLEL_HASKELL)
281 #define TERMINATION_CONDITION (!receivedFinish)
283 #define TERMINATION_CONDITION rtsTrue
286 while (TERMINATION_CONDITION) {
288 // Check whether we have re-entered the RTS from Haskell without
289 // going via suspendThread()/resumeThread (i.e. a 'safe' foreign
291 if (cap->in_haskell) {
292 errorBelch("schedule: re-entered unsafely.\n"
293 " Perhaps a 'foreign import unsafe' should be 'safe'?");
294 stg_exit(EXIT_FAILURE);
297 // The interruption / shutdown sequence.
299 // In order to cleanly shut down the runtime, we want to:
300 // * make sure that all main threads return to their callers
301 // with the state 'Interrupted'.
302 // * clean up all OS threads assocated with the runtime
303 // * free all memory etc.
305 // So the sequence for ^C goes like this:
307 // * ^C handler sets sched_state := SCHED_INTERRUPTING and
308 // arranges for some Capability to wake up
310 // * all threads in the system are halted, and the zombies are
311 // placed on the run queue for cleaning up. We acquire all
312 // the capabilities in order to delete the threads, this is
313 // done by scheduleDoGC() for convenience (because GC already
314 // needs to acquire all the capabilities). We can't kill
315 // threads involved in foreign calls.
317 // * somebody calls shutdownHaskell(), which calls exitScheduler()
319 // * sched_state := SCHED_SHUTTING_DOWN
321 // * all workers exit when the run queue on their capability
322 // drains. All main threads will also exit when their TSO
323 // reaches the head of the run queue and they can return.
325 // * eventually all Capabilities will shut down, and the RTS can
328 // * We might be left with threads blocked in foreign calls,
329 // we should really attempt to kill these somehow (TODO);
331 switch (sched_state) {
334 case SCHED_INTERRUPTING:
335 debugTrace(DEBUG_sched, "SCHED_INTERRUPTING");
336 #if defined(THREADED_RTS)
337 discardSparksCap(cap);
339 /* scheduleDoGC() deletes all the threads */
340 cap = scheduleDoGC(cap,task,rtsFalse);
342 case SCHED_SHUTTING_DOWN:
343 debugTrace(DEBUG_sched, "SCHED_SHUTTING_DOWN");
344 // If we are a worker, just exit. If we're a bound thread
345 // then we will exit below when we've removed our TSO from
347 if (task->tso == NULL && emptyRunQueue(cap)) {
352 barf("sched_state: %d", sched_state);
355 scheduleFindWork(cap);
357 /* work pushing, currently relevant only for THREADED_RTS:
358 (pushes threads, wakes up idle capabilities for stealing) */
359 schedulePushWork(cap,task);
361 #if defined(PARALLEL_HASKELL)
362 /* since we perform a blocking receive and continue otherwise,
363 either we never reach here or we definitely have work! */
364 // from here: non-empty run queue
365 ASSERT(!emptyRunQueue(cap));
367 if (PacketsWaiting()) { /* now process incoming messages, if any
370 CAUTION: scheduleGetRemoteWork called
371 above, waits for messages as well! */
372 processMessages(cap, &receivedFinish);
374 #endif // PARALLEL_HASKELL: non-empty run queue!
376 scheduleDetectDeadlock(cap,task);
378 #if defined(THREADED_RTS)
379 cap = task->cap; // reload cap, it might have changed
382 // Normally, the only way we can get here with no threads to
383 // run is if a keyboard interrupt received during
384 // scheduleCheckBlockedThreads() or scheduleDetectDeadlock().
385 // Additionally, it is not fatal for the
386 // threaded RTS to reach here with no threads to run.
388 // win32: might be here due to awaitEvent() being abandoned
389 // as a result of a console event having been delivered.
391 #if defined(THREADED_RTS)
395 // // don't yield the first time, we want a chance to run this
396 // // thread for a bit, even if there are others banging at the
399 // ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task);
403 scheduleYield(&cap,task);
404 if (emptyRunQueue(cap)) continue; // look for work again
407 #if !defined(THREADED_RTS) && !defined(mingw32_HOST_OS)
408 if ( emptyRunQueue(cap) ) {
409 ASSERT(sched_state >= SCHED_INTERRUPTING);
414 // Get a thread to run
416 t = popRunQueue(cap);
418 // Sanity check the thread we're about to run. This can be
419 // expensive if there is lots of thread switching going on...
420 IF_DEBUG(sanity,checkTSO(t));
422 #if defined(THREADED_RTS)
423 // Check whether we can run this thread in the current task.
424 // If not, we have to pass our capability to the right task.
426 Task *bound = t->bound;
430 debugTrace(DEBUG_sched,
431 "### Running thread %lu in bound thread", (unsigned long)t->id);
432 // yes, the Haskell thread is bound to the current native thread
434 debugTrace(DEBUG_sched,
435 "### thread %lu bound to another OS thread", (unsigned long)t->id);
436 // no, bound to a different Haskell thread: pass to that thread
437 pushOnRunQueue(cap,t);
441 // The thread we want to run is unbound.
443 debugTrace(DEBUG_sched,
444 "### this OS thread cannot run thread %lu", (unsigned long)t->id);
445 // no, the current native thread is bound to a different
446 // Haskell thread, so pass it to any worker thread
447 pushOnRunQueue(cap,t);
454 /* context switches are initiated by the timer signal, unless
455 * the user specified "context switch as often as possible", with
458 if (RtsFlags.ConcFlags.ctxtSwitchTicks == 0
459 && !emptyThreadQueues(cap)) {
460 cap->context_switch = 1;
465 // CurrentTSO is the thread to run. t might be different if we
466 // loop back to run_thread, so make sure to set CurrentTSO after
468 cap->r.rCurrentTSO = t;
470 debugTrace(DEBUG_sched, "-->> running thread %ld %s ...",
471 (long)t->id, whatNext_strs[t->what_next]);
473 startHeapProfTimer();
475 // Check for exceptions blocked on this thread
476 maybePerformBlockedException (cap, t);
478 // ----------------------------------------------------------------------
479 // Run the current thread
481 ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task);
482 ASSERT(t->cap == cap);
483 ASSERT(t->bound ? t->bound->cap == cap : 1);
485 prev_what_next = t->what_next;
487 errno = t->saved_errno;
489 SetLastError(t->saved_winerror);
492 cap->in_haskell = rtsTrue;
496 #if defined(THREADED_RTS)
497 if (recent_activity == ACTIVITY_DONE_GC) {
498 // ACTIVITY_DONE_GC means we turned off the timer signal to
499 // conserve power (see #1623). Re-enable it here.
501 prev = xchg((P_)&recent_activity, ACTIVITY_YES);
502 if (prev == ACTIVITY_DONE_GC) {
506 recent_activity = ACTIVITY_YES;
510 switch (prev_what_next) {
514 /* Thread already finished, return to scheduler. */
515 ret = ThreadFinished;
521 r = StgRun((StgFunPtr) stg_returnToStackTop, &cap->r);
522 cap = regTableToCapability(r);
527 case ThreadInterpret:
528 cap = interpretBCO(cap);
533 barf("schedule: invalid what_next field");
536 cap->in_haskell = rtsFalse;
538 // The TSO might have moved, eg. if it re-entered the RTS and a GC
539 // happened. So find the new location:
540 t = cap->r.rCurrentTSO;
542 // We have run some Haskell code: there might be blackhole-blocked
543 // threads to wake up now.
544 // Lock-free test here should be ok, we're just setting a flag.
545 if ( blackhole_queue != END_TSO_QUEUE ) {
546 blackholes_need_checking = rtsTrue;
549 // And save the current errno in this thread.
550 // XXX: possibly bogus for SMP because this thread might already
551 // be running again, see code below.
552 t->saved_errno = errno;
554 // Similarly for Windows error code
555 t->saved_winerror = GetLastError();
558 #if defined(THREADED_RTS)
559 // If ret is ThreadBlocked, and this Task is bound to the TSO that
560 // blocked, we are in limbo - the TSO is now owned by whatever it
561 // is blocked on, and may in fact already have been woken up,
562 // perhaps even on a different Capability. It may be the case
563 // that task->cap != cap. We better yield this Capability
564 // immediately and return to normaility.
565 if (ret == ThreadBlocked) {
566 debugTrace(DEBUG_sched,
567 "--<< thread %lu (%s) stopped: blocked",
568 (unsigned long)t->id, whatNext_strs[t->what_next]);
573 ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task);
574 ASSERT(t->cap == cap);
576 // ----------------------------------------------------------------------
578 // Costs for the scheduler are assigned to CCS_SYSTEM
580 #if defined(PROFILING)
584 schedulePostRunThread(cap,t);
586 t = threadStackUnderflow(task,t);
588 ready_to_gc = rtsFalse;
592 ready_to_gc = scheduleHandleHeapOverflow(cap,t);
596 scheduleHandleStackOverflow(cap,task,t);
600 if (scheduleHandleYield(cap, t, prev_what_next)) {
601 // shortcut for switching between compiler/interpreter:
607 scheduleHandleThreadBlocked(t);
611 if (scheduleHandleThreadFinished(cap, task, t)) return cap;
612 ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task);
616 barf("schedule: invalid thread return code %d", (int)ret);
619 if (ready_to_gc || scheduleNeedHeapProfile(ready_to_gc)) {
620 cap = scheduleDoGC(cap,task,rtsFalse);
622 } /* end of while() */
625 /* ----------------------------------------------------------------------------
626 * Setting up the scheduler loop
627 * ------------------------------------------------------------------------- */
630 schedulePreLoop(void)
632 // initialisation for scheduler - what cannot go into initScheduler()
635 /* -----------------------------------------------------------------------------
638 * Search for work to do, and handle messages from elsewhere.
639 * -------------------------------------------------------------------------- */
642 scheduleFindWork (Capability *cap)
644 scheduleStartSignalHandlers(cap);
646 // Only check the black holes here if we've nothing else to do.
647 // During normal execution, the black hole list only gets checked
648 // at GC time, to avoid repeatedly traversing this possibly long
649 // list each time around the scheduler.
650 if (emptyRunQueue(cap)) { scheduleCheckBlackHoles(cap); }
652 scheduleCheckWakeupThreads(cap);
654 scheduleCheckBlockedThreads(cap);
656 #if defined(THREADED_RTS) || defined(PARALLEL_HASKELL)
657 if (emptyRunQueue(cap)) { scheduleActivateSpark(cap); }
660 #if defined(PARALLEL_HASKELL)
661 // if messages have been buffered...
662 scheduleSendPendingMessages();
665 #if defined(PARALLEL_HASKELL)
666 if (emptyRunQueue(cap)) {
667 receivedFinish = scheduleGetRemoteWork(cap);
668 continue; // a new round, (hopefully) with new work
670 in GUM, this a) sends out a FISH and returns IF no fish is
672 b) (blocking) awaits and receives messages
674 in Eden, this is only the blocking receive, as b) in GUM.
680 #if defined(THREADED_RTS)
681 STATIC_INLINE rtsBool
682 shouldYieldCapability (Capability *cap, Task *task)
684 // we need to yield this capability to someone else if..
685 // - another thread is initiating a GC
686 // - another Task is returning from a foreign call
687 // - the thread at the head of the run queue cannot be run
688 // by this Task (it is bound to another Task, or it is unbound
689 // and this task it bound).
690 return (waiting_for_gc ||
691 cap->returning_tasks_hd != NULL ||
692 (!emptyRunQueue(cap) && (task->tso == NULL
693 ? cap->run_queue_hd->bound != NULL
694 : cap->run_queue_hd->bound != task)));
697 // This is the single place where a Task goes to sleep. There are
698 // two reasons it might need to sleep:
699 // - there are no threads to run
700 // - we need to yield this Capability to someone else
701 // (see shouldYieldCapability())
703 // The return value indicates whether
706 scheduleYield (Capability **pcap, Task *task)
708 Capability *cap = *pcap;
710 // if we have work, and we don't need to give up the Capability, continue.
711 if (!shouldYieldCapability(cap,task) &&
712 (!emptyRunQueue(cap) || blackholes_need_checking))
715 // otherwise yield (sleep), and keep yielding if necessary.
717 yieldCapability(&cap,task);
719 while (shouldYieldCapability(cap,task));
721 // note there may still be no threads on the run queue at this
722 // point, the caller has to check.
729 /* -----------------------------------------------------------------------------
732 * Push work to other Capabilities if we have some.
733 * -------------------------------------------------------------------------- */
736 schedulePushWork(Capability *cap USED_IF_THREADS,
737 Task *task USED_IF_THREADS)
739 /* following code not for PARALLEL_HASKELL. I kept the call general,
740 future GUM versions might use pushing in a distributed setup */
741 #if defined(THREADED_RTS)
743 Capability *free_caps[n_capabilities], *cap0;
746 // migration can be turned off with +RTS -qg
747 if (!RtsFlags.ParFlags.migrate) return;
749 // Check whether we have more threads on our run queue, or sparks
750 // in our pool, that we could hand to another Capability.
751 if ((emptyRunQueue(cap) || cap->run_queue_hd->_link == END_TSO_QUEUE)
752 && sparkPoolSizeCap(cap) < 2) {
756 // First grab as many free Capabilities as we can.
757 for (i=0, n_free_caps=0; i < n_capabilities; i++) {
758 cap0 = &capabilities[i];
759 if (cap != cap0 && tryGrabCapability(cap0,task)) {
760 if (!emptyRunQueue(cap0) || cap->returning_tasks_hd != NULL) {
761 // it already has some work, we just grabbed it at
762 // the wrong moment. Or maybe it's deadlocked!
763 releaseCapability(cap0);
765 free_caps[n_free_caps++] = cap0;
770 // we now have n_free_caps free capabilities stashed in
771 // free_caps[]. Share our run queue equally with them. This is
772 // probably the simplest thing we could do; improvements we might
773 // want to do include:
775 // - giving high priority to moving relatively new threads, on
776 // the gournds that they haven't had time to build up a
777 // working set in the cache on this CPU/Capability.
779 // - giving low priority to moving long-lived threads
781 if (n_free_caps > 0) {
782 StgTSO *prev, *t, *next;
783 rtsBool pushed_to_all;
785 debugTrace(DEBUG_sched,
786 "cap %d: %s and %d free capabilities, sharing...",
788 (!emptyRunQueue(cap) && cap->run_queue_hd->_link != END_TSO_QUEUE)?
789 "excess threads on run queue":"sparks to share (>=2)",
793 pushed_to_all = rtsFalse;
795 if (cap->run_queue_hd != END_TSO_QUEUE) {
796 prev = cap->run_queue_hd;
798 prev->_link = END_TSO_QUEUE;
799 for (; t != END_TSO_QUEUE; t = next) {
801 t->_link = END_TSO_QUEUE;
802 if (t->what_next == ThreadRelocated
803 || t->bound == task // don't move my bound thread
804 || tsoLocked(t)) { // don't move a locked thread
805 setTSOLink(cap, prev, t);
807 } else if (i == n_free_caps) {
808 pushed_to_all = rtsTrue;
811 setTSOLink(cap, prev, t);
814 debugTrace(DEBUG_sched, "pushing thread %lu to capability %d", (unsigned long)t->id, free_caps[i]->no);
815 appendToRunQueue(free_caps[i],t);
816 if (t->bound) { t->bound->cap = free_caps[i]; }
817 t->cap = free_caps[i];
821 cap->run_queue_tl = prev;
825 /* JB I left this code in place, it would work but is not necessary */
827 // If there are some free capabilities that we didn't push any
828 // threads to, then try to push a spark to each one.
829 if (!pushed_to_all) {
831 // i is the next free capability to push to
832 for (; i < n_free_caps; i++) {
833 if (emptySparkPoolCap(free_caps[i])) {
834 spark = tryStealSpark(cap->sparks);
836 debugTrace(DEBUG_sched, "pushing spark %p to capability %d", spark, free_caps[i]->no);
837 newSpark(&(free_caps[i]->r), spark);
842 #endif /* SPARK_PUSHING */
844 // release the capabilities
845 for (i = 0; i < n_free_caps; i++) {
846 task->cap = free_caps[i];
847 releaseAndWakeupCapability(free_caps[i]);
850 task->cap = cap; // reset to point to our Capability.
852 #endif /* THREADED_RTS */
856 /* ----------------------------------------------------------------------------
857 * Start any pending signal handlers
858 * ------------------------------------------------------------------------- */
860 #if defined(RTS_USER_SIGNALS) && !defined(THREADED_RTS)
862 scheduleStartSignalHandlers(Capability *cap)
864 if (RtsFlags.MiscFlags.install_signal_handlers && signals_pending()) {
865 // safe outside the lock
866 startSignalHandlers(cap);
871 scheduleStartSignalHandlers(Capability *cap STG_UNUSED)
876 /* ----------------------------------------------------------------------------
877 * Check for blocked threads that can be woken up.
878 * ------------------------------------------------------------------------- */
881 scheduleCheckBlockedThreads(Capability *cap USED_IF_NOT_THREADS)
883 #if !defined(THREADED_RTS)
885 // Check whether any waiting threads need to be woken up. If the
886 // run queue is empty, and there are no other tasks running, we
887 // can wait indefinitely for something to happen.
889 if ( !emptyQueue(blocked_queue_hd) || !emptyQueue(sleeping_queue) )
891 awaitEvent( emptyRunQueue(cap) && !blackholes_need_checking );
897 /* ----------------------------------------------------------------------------
898 * Check for threads woken up by other Capabilities
899 * ------------------------------------------------------------------------- */
902 scheduleCheckWakeupThreads(Capability *cap USED_IF_THREADS)
904 #if defined(THREADED_RTS)
905 // Any threads that were woken up by other Capabilities get
906 // appended to our run queue.
907 if (!emptyWakeupQueue(cap)) {
908 ACQUIRE_LOCK(&cap->lock);
909 if (emptyRunQueue(cap)) {
910 cap->run_queue_hd = cap->wakeup_queue_hd;
911 cap->run_queue_tl = cap->wakeup_queue_tl;
913 setTSOLink(cap, cap->run_queue_tl, cap->wakeup_queue_hd);
914 cap->run_queue_tl = cap->wakeup_queue_tl;
916 cap->wakeup_queue_hd = cap->wakeup_queue_tl = END_TSO_QUEUE;
917 RELEASE_LOCK(&cap->lock);
922 /* ----------------------------------------------------------------------------
923 * Check for threads blocked on BLACKHOLEs that can be woken up
924 * ------------------------------------------------------------------------- */
926 scheduleCheckBlackHoles (Capability *cap)
928 if ( blackholes_need_checking ) // check without the lock first
930 ACQUIRE_LOCK(&sched_mutex);
931 if ( blackholes_need_checking ) {
932 blackholes_need_checking = rtsFalse;
933 // important that we reset the flag *before* checking the
934 // blackhole queue, otherwise we could get deadlock. This
935 // happens as follows: we wake up a thread that
936 // immediately runs on another Capability, blocks on a
937 // blackhole, and then we reset the blackholes_need_checking flag.
938 checkBlackHoles(cap);
940 RELEASE_LOCK(&sched_mutex);
944 /* ----------------------------------------------------------------------------
945 * Detect deadlock conditions and attempt to resolve them.
946 * ------------------------------------------------------------------------- */
949 scheduleDetectDeadlock (Capability *cap, Task *task)
952 #if defined(PARALLEL_HASKELL)
953 // ToDo: add deadlock detection in GUM (similar to THREADED_RTS) -- HWL
958 * Detect deadlock: when we have no threads to run, there are no
959 * threads blocked, waiting for I/O, or sleeping, and all the
960 * other tasks are waiting for work, we must have a deadlock of
963 if ( emptyThreadQueues(cap) )
965 #if defined(THREADED_RTS)
967 * In the threaded RTS, we only check for deadlock if there
968 * has been no activity in a complete timeslice. This means
969 * we won't eagerly start a full GC just because we don't have
970 * any threads to run currently.
972 if (recent_activity != ACTIVITY_INACTIVE) return;
975 debugTrace(DEBUG_sched, "deadlocked, forcing major GC...");
977 // Garbage collection can release some new threads due to
978 // either (a) finalizers or (b) threads resurrected because
979 // they are unreachable and will therefore be sent an
980 // exception. Any threads thus released will be immediately
982 cap = scheduleDoGC (cap, task, rtsTrue/*force major GC*/);
984 recent_activity = ACTIVITY_DONE_GC;
985 // disable timer signals (see #1623)
988 if ( !emptyRunQueue(cap) ) return;
990 #if defined(RTS_USER_SIGNALS) && !defined(THREADED_RTS)
991 /* If we have user-installed signal handlers, then wait
992 * for signals to arrive rather then bombing out with a
995 if ( RtsFlags.MiscFlags.install_signal_handlers && anyUserHandlers() ) {
996 debugTrace(DEBUG_sched,
997 "still deadlocked, waiting for signals...");
1001 if (signals_pending()) {
1002 startSignalHandlers(cap);
1005 // either we have threads to run, or we were interrupted:
1006 ASSERT(!emptyRunQueue(cap) || sched_state >= SCHED_INTERRUPTING);
1012 #if !defined(THREADED_RTS)
1013 /* Probably a real deadlock. Send the current main thread the
1014 * Deadlock exception.
1017 switch (task->tso->why_blocked) {
1019 case BlockedOnBlackHole:
1020 case BlockedOnException:
1022 throwToSingleThreaded(cap, task->tso,
1023 (StgClosure *)nonTermination_closure);
1026 barf("deadlock: main thread blocked in a strange way");
1035 /* ----------------------------------------------------------------------------
1036 * Send pending messages (PARALLEL_HASKELL only)
1037 * ------------------------------------------------------------------------- */
1039 #if defined(PARALLEL_HASKELL)
1041 scheduleSendPendingMessages(void)
1044 # if defined(PAR) // global Mem.Mgmt., omit for now
1045 if (PendingFetches != END_BF_QUEUE) {
1050 if (RtsFlags.ParFlags.BufferTime) {
1051 // if we use message buffering, we must send away all message
1052 // packets which have become too old...
1058 /* ----------------------------------------------------------------------------
1059 * Activate spark threads (PARALLEL_HASKELL and THREADED_RTS)
1060 * ------------------------------------------------------------------------- */
1062 #if defined(PARALLEL_HASKELL) || defined(THREADED_RTS)
1064 scheduleActivateSpark(Capability *cap)
1068 createSparkThread(cap);
1069 debugTrace(DEBUG_sched, "creating a spark thread");
1072 #endif // PARALLEL_HASKELL || THREADED_RTS
1074 /* ----------------------------------------------------------------------------
1075 * Get work from a remote node (PARALLEL_HASKELL only)
1076 * ------------------------------------------------------------------------- */
1078 #if defined(PARALLEL_HASKELL)
1079 static rtsBool /* return value used in PARALLEL_HASKELL only */
1080 scheduleGetRemoteWork (Capability *cap STG_UNUSED)
1082 #if defined(PARALLEL_HASKELL)
1083 rtsBool receivedFinish = rtsFalse;
1085 // idle() , i.e. send all buffers, wait for work
1086 if (RtsFlags.ParFlags.BufferTime) {
1087 IF_PAR_DEBUG(verbose,
1088 debugBelch("...send all pending data,"));
1091 for (i=1; i<=nPEs; i++)
1092 sendImmediately(i); // send all messages away immediately
1096 /* this would be the place for fishing in GUM...
1098 if (no-earlier-fish-around)
1099 sendFish(choosePe());
1102 // Eden:just look for incoming messages (blocking receive)
1103 IF_PAR_DEBUG(verbose,
1104 debugBelch("...wait for incoming messages...\n"));
1105 processMessages(cap, &receivedFinish); // blocking receive...
1108 return receivedFinish;
1109 // reenter scheduling look after having received something
1111 #else /* !PARALLEL_HASKELL, i.e. THREADED_RTS */
1113 return rtsFalse; /* return value unused in THREADED_RTS */
1115 #endif /* PARALLEL_HASKELL */
1117 #endif // PARALLEL_HASKELL || THREADED_RTS
1119 /* ----------------------------------------------------------------------------
1120 * After running a thread...
1121 * ------------------------------------------------------------------------- */
1124 schedulePostRunThread (Capability *cap, StgTSO *t)
1126 // We have to be able to catch transactions that are in an
1127 // infinite loop as a result of seeing an inconsistent view of
1131 // [a,b] <- mapM readTVar [ta,tb]
1132 // when (a == b) loop
1134 // and a is never equal to b given a consistent view of memory.
1136 if (t -> trec != NO_TREC && t -> why_blocked == NotBlocked) {
1137 if (!stmValidateNestOfTransactions (t -> trec)) {
1138 debugTrace(DEBUG_sched | DEBUG_stm,
1139 "trec %p found wasting its time", t);
1141 // strip the stack back to the
1142 // ATOMICALLY_FRAME, aborting the (nested)
1143 // transaction, and saving the stack of any
1144 // partially-evaluated thunks on the heap.
1145 throwToSingleThreaded_(cap, t, NULL, rtsTrue, NULL);
1147 ASSERT(get_itbl((StgClosure *)t->sp)->type == ATOMICALLY_FRAME);
1151 /* some statistics gathering in the parallel case */
1154 /* -----------------------------------------------------------------------------
1155 * Handle a thread that returned to the scheduler with ThreadHeepOverflow
1156 * -------------------------------------------------------------------------- */
1159 scheduleHandleHeapOverflow( Capability *cap, StgTSO *t )
1161 // did the task ask for a large block?
1162 if (cap->r.rHpAlloc > BLOCK_SIZE) {
1163 // if so, get one and push it on the front of the nursery.
1167 blocks = (lnat)BLOCK_ROUND_UP(cap->r.rHpAlloc) / BLOCK_SIZE;
1169 debugTrace(DEBUG_sched,
1170 "--<< thread %ld (%s) stopped: requesting a large block (size %ld)\n",
1171 (long)t->id, whatNext_strs[t->what_next], blocks);
1173 // don't do this if the nursery is (nearly) full, we'll GC first.
1174 if (cap->r.rCurrentNursery->link != NULL ||
1175 cap->r.rNursery->n_blocks == 1) { // paranoia to prevent infinite loop
1176 // if the nursery has only one block.
1179 bd = allocGroup( blocks );
1181 cap->r.rNursery->n_blocks += blocks;
1183 // link the new group into the list
1184 bd->link = cap->r.rCurrentNursery;
1185 bd->u.back = cap->r.rCurrentNursery->u.back;
1186 if (cap->r.rCurrentNursery->u.back != NULL) {
1187 cap->r.rCurrentNursery->u.back->link = bd;
1189 #if !defined(THREADED_RTS)
1190 ASSERT(g0s0->blocks == cap->r.rCurrentNursery &&
1191 g0s0 == cap->r.rNursery);
1193 cap->r.rNursery->blocks = bd;
1195 cap->r.rCurrentNursery->u.back = bd;
1197 // initialise it as a nursery block. We initialise the
1198 // step, gen_no, and flags field of *every* sub-block in
1199 // this large block, because this is easier than making
1200 // sure that we always find the block head of a large
1201 // block whenever we call Bdescr() (eg. evacuate() and
1202 // isAlive() in the GC would both have to do this, at
1206 for (x = bd; x < bd + blocks; x++) {
1207 x->step = cap->r.rNursery;
1213 // This assert can be a killer if the app is doing lots
1214 // of large block allocations.
1215 IF_DEBUG(sanity, checkNurserySanity(cap->r.rNursery));
1217 // now update the nursery to point to the new block
1218 cap->r.rCurrentNursery = bd;
1220 // we might be unlucky and have another thread get on the
1221 // run queue before us and steal the large block, but in that
1222 // case the thread will just end up requesting another large
1224 pushOnRunQueue(cap,t);
1225 return rtsFalse; /* not actually GC'ing */
1229 debugTrace(DEBUG_sched,
1230 "--<< thread %ld (%s) stopped: HeapOverflow",
1231 (long)t->id, whatNext_strs[t->what_next]);
1233 if (cap->context_switch) {
1234 // Sometimes we miss a context switch, e.g. when calling
1235 // primitives in a tight loop, MAYBE_GC() doesn't check the
1236 // context switch flag, and we end up waiting for a GC.
1237 // See #1984, and concurrent/should_run/1984
1238 cap->context_switch = 0;
1239 addToRunQueue(cap,t);
1241 pushOnRunQueue(cap,t);
1244 /* actual GC is done at the end of the while loop in schedule() */
1247 /* -----------------------------------------------------------------------------
1248 * Handle a thread that returned to the scheduler with ThreadStackOverflow
1249 * -------------------------------------------------------------------------- */
1252 scheduleHandleStackOverflow (Capability *cap, Task *task, StgTSO *t)
1254 debugTrace (DEBUG_sched,
1255 "--<< thread %ld (%s) stopped, StackOverflow",
1256 (long)t->id, whatNext_strs[t->what_next]);
1258 /* just adjust the stack for this thread, then pop it back
1262 /* enlarge the stack */
1263 StgTSO *new_t = threadStackOverflow(cap, t);
1265 /* The TSO attached to this Task may have moved, so update the
1268 if (task->tso == t) {
1271 pushOnRunQueue(cap,new_t);
1275 /* -----------------------------------------------------------------------------
1276 * Handle a thread that returned to the scheduler with ThreadYielding
1277 * -------------------------------------------------------------------------- */
1280 scheduleHandleYield( Capability *cap, StgTSO *t, nat prev_what_next )
1282 // Reset the context switch flag. We don't do this just before
1283 // running the thread, because that would mean we would lose ticks
1284 // during GC, which can lead to unfair scheduling (a thread hogs
1285 // the CPU because the tick always arrives during GC). This way
1286 // penalises threads that do a lot of allocation, but that seems
1287 // better than the alternative.
1288 cap->context_switch = 0;
1290 /* put the thread back on the run queue. Then, if we're ready to
1291 * GC, check whether this is the last task to stop. If so, wake
1292 * up the GC thread. getThread will block during a GC until the
1296 if (t->what_next != prev_what_next) {
1297 debugTrace(DEBUG_sched,
1298 "--<< thread %ld (%s) stopped to switch evaluators",
1299 (long)t->id, whatNext_strs[t->what_next]);
1301 debugTrace(DEBUG_sched,
1302 "--<< thread %ld (%s) stopped, yielding",
1303 (long)t->id, whatNext_strs[t->what_next]);
1308 //debugBelch("&& Doing sanity check on yielding TSO %ld.", t->id);
1310 ASSERT(t->_link == END_TSO_QUEUE);
1312 // Shortcut if we're just switching evaluators: don't bother
1313 // doing stack squeezing (which can be expensive), just run the
1315 if (t->what_next != prev_what_next) {
1319 addToRunQueue(cap,t);
1324 /* -----------------------------------------------------------------------------
1325 * Handle a thread that returned to the scheduler with ThreadBlocked
1326 * -------------------------------------------------------------------------- */
1329 scheduleHandleThreadBlocked( StgTSO *t
1330 #if !defined(GRAN) && !defined(DEBUG)
1336 // We don't need to do anything. The thread is blocked, and it
1337 // has tidied up its stack and placed itself on whatever queue
1338 // it needs to be on.
1340 // ASSERT(t->why_blocked != NotBlocked);
1341 // Not true: for example,
1342 // - in THREADED_RTS, the thread may already have been woken
1343 // up by another Capability. This actually happens: try
1344 // conc023 +RTS -N2.
1345 // - the thread may have woken itself up already, because
1346 // threadPaused() might have raised a blocked throwTo
1347 // exception, see maybePerformBlockedException().
1350 if (traceClass(DEBUG_sched)) {
1351 debugTraceBegin("--<< thread %lu (%s) stopped: ",
1352 (unsigned long)t->id, whatNext_strs[t->what_next]);
1353 printThreadBlockage(t);
1359 /* -----------------------------------------------------------------------------
1360 * Handle a thread that returned to the scheduler with ThreadFinished
1361 * -------------------------------------------------------------------------- */
1364 scheduleHandleThreadFinished (Capability *cap STG_UNUSED, Task *task, StgTSO *t)
1366 /* Need to check whether this was a main thread, and if so,
1367 * return with the return value.
1369 * We also end up here if the thread kills itself with an
1370 * uncaught exception, see Exception.cmm.
1372 debugTrace(DEBUG_sched, "--++ thread %lu (%s) finished",
1373 (unsigned long)t->id, whatNext_strs[t->what_next]);
1376 // Check whether the thread that just completed was a bound
1377 // thread, and if so return with the result.
1379 // There is an assumption here that all thread completion goes
1380 // through this point; we need to make sure that if a thread
1381 // ends up in the ThreadKilled state, that it stays on the run
1382 // queue so it can be dealt with here.
1387 if (t->bound != task) {
1388 #if !defined(THREADED_RTS)
1389 // Must be a bound thread that is not the topmost one. Leave
1390 // it on the run queue until the stack has unwound to the
1391 // point where we can deal with this. Leaving it on the run
1392 // queue also ensures that the garbage collector knows about
1393 // this thread and its return value (it gets dropped from the
1394 // step->threads list so there's no other way to find it).
1395 appendToRunQueue(cap,t);
1398 // this cannot happen in the threaded RTS, because a
1399 // bound thread can only be run by the appropriate Task.
1400 barf("finished bound thread that isn't mine");
1404 ASSERT(task->tso == t);
1406 if (t->what_next == ThreadComplete) {
1408 // NOTE: return val is tso->sp[1] (see StgStartup.hc)
1409 *(task->ret) = (StgClosure *)task->tso->sp[1];
1411 task->stat = Success;
1414 *(task->ret) = NULL;
1416 if (sched_state >= SCHED_INTERRUPTING) {
1417 task->stat = Interrupted;
1419 task->stat = Killed;
1423 removeThreadLabel((StgWord)task->tso->id);
1425 return rtsTrue; // tells schedule() to return
1431 /* -----------------------------------------------------------------------------
1432 * Perform a heap census
1433 * -------------------------------------------------------------------------- */
1436 scheduleNeedHeapProfile( rtsBool ready_to_gc STG_UNUSED )
1438 // When we have +RTS -i0 and we're heap profiling, do a census at
1439 // every GC. This lets us get repeatable runs for debugging.
1440 if (performHeapProfile ||
1441 (RtsFlags.ProfFlags.profileInterval==0 &&
1442 RtsFlags.ProfFlags.doHeapProfile && ready_to_gc)) {
1449 /* -----------------------------------------------------------------------------
1450 * Perform a garbage collection if necessary
1451 * -------------------------------------------------------------------------- */
1454 scheduleDoGC (Capability *cap, Task *task USED_IF_THREADS, rtsBool force_major)
1456 rtsBool heap_census;
1458 /* extern static volatile StgWord waiting_for_gc;
1459 lives inside capability.c */
1460 rtsBool was_waiting;
1465 // In order to GC, there must be no threads running Haskell code.
1466 // Therefore, the GC thread needs to hold *all* the capabilities,
1467 // and release them after the GC has completed.
1469 // This seems to be the simplest way: previous attempts involved
1470 // making all the threads with capabilities give up their
1471 // capabilities and sleep except for the *last* one, which
1472 // actually did the GC. But it's quite hard to arrange for all
1473 // the other tasks to sleep and stay asleep.
1476 /* Other capabilities are prevented from running yet more Haskell
1477 threads if waiting_for_gc is set. Tested inside
1478 yieldCapability() and releaseCapability() in Capability.c */
1480 was_waiting = cas(&waiting_for_gc, 0, 1);
1483 debugTrace(DEBUG_sched, "someone else is trying to GC...");
1484 if (cap) yieldCapability(&cap,task);
1485 } while (waiting_for_gc);
1486 return cap; // NOTE: task->cap might have changed here
1489 setContextSwitches();
1490 for (i=0; i < n_capabilities; i++) {
1491 debugTrace(DEBUG_sched, "ready_to_gc, grabbing all the capabilies (%d/%d)", i, n_capabilities);
1492 if (cap != &capabilities[i]) {
1493 Capability *pcap = &capabilities[i];
1494 // we better hope this task doesn't get migrated to
1495 // another Capability while we're waiting for this one.
1496 // It won't, because load balancing happens while we have
1497 // all the Capabilities, but even so it's a slightly
1498 // unsavoury invariant.
1500 waitForReturnCapability(&pcap, task);
1501 if (pcap != &capabilities[i]) {
1502 barf("scheduleDoGC: got the wrong capability");
1507 waiting_for_gc = rtsFalse;
1510 // so this happens periodically:
1511 if (cap) scheduleCheckBlackHoles(cap);
1513 IF_DEBUG(scheduler, printAllThreads());
1516 * We now have all the capabilities; if we're in an interrupting
1517 * state, then we should take the opportunity to delete all the
1518 * threads in the system.
1520 if (sched_state >= SCHED_INTERRUPTING) {
1521 deleteAllThreads(&capabilities[0]);
1522 sched_state = SCHED_SHUTTING_DOWN;
1525 heap_census = scheduleNeedHeapProfile(rtsTrue);
1527 /* everybody back, start the GC.
1528 * Could do it in this thread, or signal a condition var
1529 * to do it in another thread. Either way, we need to
1530 * broadcast on gc_pending_cond afterward.
1532 #if defined(THREADED_RTS)
1533 debugTrace(DEBUG_sched, "doing GC");
1535 GarbageCollect(force_major || heap_census);
1538 debugTrace(DEBUG_sched, "performing heap census");
1540 performHeapProfile = rtsFalse;
1545 Once we are all together... this would be the place to balance all
1546 spark pools. No concurrent stealing or adding of new sparks can
1547 occur. Should be defined in Sparks.c. */
1548 balanceSparkPoolsCaps(n_capabilities, capabilities);
1551 #if defined(THREADED_RTS)
1552 // release our stash of capabilities.
1553 for (i = 0; i < n_capabilities; i++) {
1554 if (cap != &capabilities[i]) {
1555 task->cap = &capabilities[i];
1556 releaseCapability(&capabilities[i]);
1569 /* ---------------------------------------------------------------------------
1570 * Singleton fork(). Do not copy any running threads.
1571 * ------------------------------------------------------------------------- */
1574 forkProcess(HsStablePtr *entry
1575 #ifndef FORKPROCESS_PRIMOP_SUPPORTED
1580 #ifdef FORKPROCESS_PRIMOP_SUPPORTED
1587 #if defined(THREADED_RTS)
1588 if (RtsFlags.ParFlags.nNodes > 1) {
1589 errorBelch("forking not supported with +RTS -N<n> greater than 1");
1590 stg_exit(EXIT_FAILURE);
1594 debugTrace(DEBUG_sched, "forking!");
1596 // ToDo: for SMP, we should probably acquire *all* the capabilities
1599 // no funny business: hold locks while we fork, otherwise if some
1600 // other thread is holding a lock when the fork happens, the data
1601 // structure protected by the lock will forever be in an
1602 // inconsistent state in the child. See also #1391.
1603 ACQUIRE_LOCK(&sched_mutex);
1604 ACQUIRE_LOCK(&cap->lock);
1605 ACQUIRE_LOCK(&cap->running_task->lock);
1609 if (pid) { // parent
1611 RELEASE_LOCK(&sched_mutex);
1612 RELEASE_LOCK(&cap->lock);
1613 RELEASE_LOCK(&cap->running_task->lock);
1615 // just return the pid
1621 #if defined(THREADED_RTS)
1622 initMutex(&sched_mutex);
1623 initMutex(&cap->lock);
1624 initMutex(&cap->running_task->lock);
1627 // Now, all OS threads except the thread that forked are
1628 // stopped. We need to stop all Haskell threads, including
1629 // those involved in foreign calls. Also we need to delete
1630 // all Tasks, because they correspond to OS threads that are
1633 for (s = 0; s < total_steps; s++) {
1634 for (t = all_steps[s].threads; t != END_TSO_QUEUE; t = next) {
1635 if (t->what_next == ThreadRelocated) {
1638 next = t->global_link;
1639 // don't allow threads to catch the ThreadKilled
1640 // exception, but we do want to raiseAsync() because these
1641 // threads may be evaluating thunks that we need later.
1642 deleteThread_(cap,t);
1647 // Empty the run queue. It seems tempting to let all the
1648 // killed threads stay on the run queue as zombies to be
1649 // cleaned up later, but some of them correspond to bound
1650 // threads for which the corresponding Task does not exist.
1651 cap->run_queue_hd = END_TSO_QUEUE;
1652 cap->run_queue_tl = END_TSO_QUEUE;
1654 // Any suspended C-calling Tasks are no more, their OS threads
1656 cap->suspended_ccalling_tasks = NULL;
1658 // Empty the threads lists. Otherwise, the garbage
1659 // collector may attempt to resurrect some of these threads.
1660 for (s = 0; s < total_steps; s++) {
1661 all_steps[s].threads = END_TSO_QUEUE;
1664 // Wipe the task list, except the current Task.
1665 ACQUIRE_LOCK(&sched_mutex);
1666 for (task = all_tasks; task != NULL; task=task->all_link) {
1667 if (task != cap->running_task) {
1668 #if defined(THREADED_RTS)
1669 initMutex(&task->lock); // see #1391
1674 RELEASE_LOCK(&sched_mutex);
1676 #if defined(THREADED_RTS)
1677 // Wipe our spare workers list, they no longer exist. New
1678 // workers will be created if necessary.
1679 cap->spare_workers = NULL;
1680 cap->returning_tasks_hd = NULL;
1681 cap->returning_tasks_tl = NULL;
1684 // On Unix, all timers are reset in the child, so we need to start
1689 cap = rts_evalStableIO(cap, entry, NULL); // run the action
1690 rts_checkSchedStatus("forkProcess",cap);
1693 hs_exit(); // clean up and exit
1694 stg_exit(EXIT_SUCCESS);
1696 #else /* !FORKPROCESS_PRIMOP_SUPPORTED */
1697 barf("forkProcess#: primop not supported on this platform, sorry!\n");
1702 /* ---------------------------------------------------------------------------
1703 * Delete all the threads in the system
1704 * ------------------------------------------------------------------------- */
1707 deleteAllThreads ( Capability *cap )
1709 // NOTE: only safe to call if we own all capabilities.
1714 debugTrace(DEBUG_sched,"deleting all threads");
1715 for (s = 0; s < total_steps; s++) {
1716 for (t = all_steps[s].threads; t != END_TSO_QUEUE; t = next) {
1717 if (t->what_next == ThreadRelocated) {
1720 next = t->global_link;
1721 deleteThread(cap,t);
1726 // The run queue now contains a bunch of ThreadKilled threads. We
1727 // must not throw these away: the main thread(s) will be in there
1728 // somewhere, and the main scheduler loop has to deal with it.
1729 // Also, the run queue is the only thing keeping these threads from
1730 // being GC'd, and we don't want the "main thread has been GC'd" panic.
1732 #if !defined(THREADED_RTS)
1733 ASSERT(blocked_queue_hd == END_TSO_QUEUE);
1734 ASSERT(sleeping_queue == END_TSO_QUEUE);
1738 /* -----------------------------------------------------------------------------
1739 Managing the suspended_ccalling_tasks list.
1740 Locks required: sched_mutex
1741 -------------------------------------------------------------------------- */
1744 suspendTask (Capability *cap, Task *task)
1746 ASSERT(task->next == NULL && task->prev == NULL);
1747 task->next = cap->suspended_ccalling_tasks;
1749 if (cap->suspended_ccalling_tasks) {
1750 cap->suspended_ccalling_tasks->prev = task;
1752 cap->suspended_ccalling_tasks = task;
1756 recoverSuspendedTask (Capability *cap, Task *task)
1759 task->prev->next = task->next;
1761 ASSERT(cap->suspended_ccalling_tasks == task);
1762 cap->suspended_ccalling_tasks = task->next;
1765 task->next->prev = task->prev;
1767 task->next = task->prev = NULL;
1770 /* ---------------------------------------------------------------------------
1771 * Suspending & resuming Haskell threads.
1773 * When making a "safe" call to C (aka _ccall_GC), the task gives back
1774 * its capability before calling the C function. This allows another
1775 * task to pick up the capability and carry on running Haskell
1776 * threads. It also means that if the C call blocks, it won't lock
1779 * The Haskell thread making the C call is put to sleep for the
1780 * duration of the call, on the susepended_ccalling_threads queue. We
1781 * give out a token to the task, which it can use to resume the thread
1782 * on return from the C function.
1783 * ------------------------------------------------------------------------- */
1786 suspendThread (StgRegTable *reg)
1793 StgWord32 saved_winerror;
1796 saved_errno = errno;
1798 saved_winerror = GetLastError();
1801 /* assume that *reg is a pointer to the StgRegTable part of a Capability.
1803 cap = regTableToCapability(reg);
1805 task = cap->running_task;
1806 tso = cap->r.rCurrentTSO;
1808 debugTrace(DEBUG_sched,
1809 "thread %lu did a safe foreign call",
1810 (unsigned long)cap->r.rCurrentTSO->id);
1812 // XXX this might not be necessary --SDM
1813 tso->what_next = ThreadRunGHC;
1815 threadPaused(cap,tso);
1817 if ((tso->flags & TSO_BLOCKEX) == 0) {
1818 tso->why_blocked = BlockedOnCCall;
1819 tso->flags |= TSO_BLOCKEX;
1820 tso->flags &= ~TSO_INTERRUPTIBLE;
1822 tso->why_blocked = BlockedOnCCall_NoUnblockExc;
1825 // Hand back capability
1826 task->suspended_tso = tso;
1828 ACQUIRE_LOCK(&cap->lock);
1830 suspendTask(cap,task);
1831 cap->in_haskell = rtsFalse;
1832 releaseCapability_(cap,rtsFalse);
1834 RELEASE_LOCK(&cap->lock);
1836 #if defined(THREADED_RTS)
1837 /* Preparing to leave the RTS, so ensure there's a native thread/task
1838 waiting to take over.
1840 debugTrace(DEBUG_sched, "thread %lu: leaving RTS", (unsigned long)tso->id);
1843 errno = saved_errno;
1845 SetLastError(saved_winerror);
1851 resumeThread (void *task_)
1858 StgWord32 saved_winerror;
1861 saved_errno = errno;
1863 saved_winerror = GetLastError();
1867 // Wait for permission to re-enter the RTS with the result.
1868 waitForReturnCapability(&cap,task);
1869 // we might be on a different capability now... but if so, our
1870 // entry on the suspended_ccalling_tasks list will also have been
1873 // Remove the thread from the suspended list
1874 recoverSuspendedTask(cap,task);
1876 tso = task->suspended_tso;
1877 task->suspended_tso = NULL;
1878 tso->_link = END_TSO_QUEUE; // no write barrier reqd
1879 debugTrace(DEBUG_sched, "thread %lu: re-entering RTS", (unsigned long)tso->id);
1881 if (tso->why_blocked == BlockedOnCCall) {
1882 awakenBlockedExceptionQueue(cap,tso);
1883 tso->flags &= ~(TSO_BLOCKEX | TSO_INTERRUPTIBLE);
1886 /* Reset blocking status */
1887 tso->why_blocked = NotBlocked;
1889 cap->r.rCurrentTSO = tso;
1890 cap->in_haskell = rtsTrue;
1891 errno = saved_errno;
1893 SetLastError(saved_winerror);
1896 /* We might have GC'd, mark the TSO dirty again */
1899 IF_DEBUG(sanity, checkTSO(tso));
1904 /* ---------------------------------------------------------------------------
1907 * scheduleThread puts a thread on the end of the runnable queue.
1908 * This will usually be done immediately after a thread is created.
1909 * The caller of scheduleThread must create the thread using e.g.
1910 * createThread and push an appropriate closure
1911 * on this thread's stack before the scheduler is invoked.
1912 * ------------------------------------------------------------------------ */
1915 scheduleThread(Capability *cap, StgTSO *tso)
1917 // The thread goes at the *end* of the run-queue, to avoid possible
1918 // starvation of any threads already on the queue.
1919 appendToRunQueue(cap,tso);
1923 scheduleThreadOn(Capability *cap, StgWord cpu USED_IF_THREADS, StgTSO *tso)
1925 #if defined(THREADED_RTS)
1926 tso->flags |= TSO_LOCKED; // we requested explicit affinity; don't
1927 // move this thread from now on.
1928 cpu %= RtsFlags.ParFlags.nNodes;
1929 if (cpu == cap->no) {
1930 appendToRunQueue(cap,tso);
1932 wakeupThreadOnCapability(cap, &capabilities[cpu], tso);
1935 appendToRunQueue(cap,tso);
1940 scheduleWaitThread (StgTSO* tso, /*[out]*/HaskellObj* ret, Capability *cap)
1944 // We already created/initialised the Task
1945 task = cap->running_task;
1947 // This TSO is now a bound thread; make the Task and TSO
1948 // point to each other.
1954 task->stat = NoStatus;
1956 appendToRunQueue(cap,tso);
1958 debugTrace(DEBUG_sched, "new bound thread (%lu)", (unsigned long)tso->id);
1960 cap = schedule(cap,task);
1962 ASSERT(task->stat != NoStatus);
1963 ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task);
1965 debugTrace(DEBUG_sched, "bound thread (%lu) finished", (unsigned long)task->tso->id);
1969 /* ----------------------------------------------------------------------------
1971 * ------------------------------------------------------------------------- */
1973 #if defined(THREADED_RTS)
1974 void OSThreadProcAttr
1975 workerStart(Task *task)
1979 // See startWorkerTask().
1980 ACQUIRE_LOCK(&task->lock);
1982 RELEASE_LOCK(&task->lock);
1984 // set the thread-local pointer to the Task:
1987 // schedule() runs without a lock.
1988 cap = schedule(cap,task);
1990 // On exit from schedule(), we have a Capability.
1991 releaseCapability(cap);
1992 workerTaskStop(task);
1996 /* ---------------------------------------------------------------------------
1999 * Initialise the scheduler. This resets all the queues - if the
2000 * queues contained any threads, they'll be garbage collected at the
2003 * ------------------------------------------------------------------------ */
2008 #if !defined(THREADED_RTS)
2009 blocked_queue_hd = END_TSO_QUEUE;
2010 blocked_queue_tl = END_TSO_QUEUE;
2011 sleeping_queue = END_TSO_QUEUE;
2014 blackhole_queue = END_TSO_QUEUE;
2016 sched_state = SCHED_RUNNING;
2017 recent_activity = ACTIVITY_YES;
2019 #if defined(THREADED_RTS)
2020 /* Initialise the mutex and condition variables used by
2022 initMutex(&sched_mutex);
2025 ACQUIRE_LOCK(&sched_mutex);
2027 /* A capability holds the state a native thread needs in
2028 * order to execute STG code. At least one capability is
2029 * floating around (only THREADED_RTS builds have more than one).
2035 #if defined(THREADED_RTS) || defined(PARALLEL_HASKELL)
2039 #if defined(THREADED_RTS)
2041 * Eagerly start one worker to run each Capability, except for
2042 * Capability 0. The idea is that we're probably going to start a
2043 * bound thread on Capability 0 pretty soon, so we don't want a
2044 * worker task hogging it.
2049 for (i = 1; i < n_capabilities; i++) {
2050 cap = &capabilities[i];
2051 ACQUIRE_LOCK(&cap->lock);
2052 startWorkerTask(cap, workerStart);
2053 RELEASE_LOCK(&cap->lock);
2058 trace(TRACE_sched, "start: %d capabilities", n_capabilities);
2060 RELEASE_LOCK(&sched_mutex);
2065 rtsBool wait_foreign
2066 #if !defined(THREADED_RTS)
2067 __attribute__((unused))
2070 /* see Capability.c, shutdownCapability() */
2074 #if defined(THREADED_RTS)
2075 ACQUIRE_LOCK(&sched_mutex);
2076 task = newBoundTask();
2077 RELEASE_LOCK(&sched_mutex);
2080 // If we haven't killed all the threads yet, do it now.
2081 if (sched_state < SCHED_SHUTTING_DOWN) {
2082 sched_state = SCHED_INTERRUPTING;
2083 scheduleDoGC(NULL,task,rtsFalse);
2085 sched_state = SCHED_SHUTTING_DOWN;
2087 #if defined(THREADED_RTS)
2091 for (i = 0; i < n_capabilities; i++) {
2092 shutdownCapability(&capabilities[i], task, wait_foreign);
2094 boundTaskExiting(task);
2101 freeScheduler( void )
2105 if (n_capabilities != 1) {
2106 stgFree(capabilities);
2108 #if defined(THREADED_RTS)
2109 closeMutex(&sched_mutex);
2113 /* -----------------------------------------------------------------------------
2116 This is the interface to the garbage collector from Haskell land.
2117 We provide this so that external C code can allocate and garbage
2118 collect when called from Haskell via _ccall_GC.
2119 -------------------------------------------------------------------------- */
2122 performGC_(rtsBool force_major)
2125 // We must grab a new Task here, because the existing Task may be
2126 // associated with a particular Capability, and chained onto the
2127 // suspended_ccalling_tasks queue.
2128 ACQUIRE_LOCK(&sched_mutex);
2129 task = newBoundTask();
2130 RELEASE_LOCK(&sched_mutex);
2131 scheduleDoGC(NULL,task,force_major);
2132 boundTaskExiting(task);
2138 performGC_(rtsFalse);
2142 performMajorGC(void)
2144 performGC_(rtsTrue);
2147 /* -----------------------------------------------------------------------------
2150 If the thread has reached its maximum stack size, then raise the
2151 StackOverflow exception in the offending thread. Otherwise
2152 relocate the TSO into a larger chunk of memory and adjust its stack
2154 -------------------------------------------------------------------------- */
2157 threadStackOverflow(Capability *cap, StgTSO *tso)
2159 nat new_stack_size, stack_words;
2164 IF_DEBUG(sanity,checkTSO(tso));
2166 // don't allow throwTo() to modify the blocked_exceptions queue
2167 // while we are moving the TSO:
2168 lockClosure((StgClosure *)tso);
2170 if (tso->stack_size >= tso->max_stack_size && !(tso->flags & TSO_BLOCKEX)) {
2171 // NB. never raise a StackOverflow exception if the thread is
2172 // inside Control.Exceptino.block. It is impractical to protect
2173 // against stack overflow exceptions, since virtually anything
2174 // can raise one (even 'catch'), so this is the only sensible
2175 // thing to do here. See bug #767.
2177 debugTrace(DEBUG_gc,
2178 "threadStackOverflow of TSO %ld (%p): stack too large (now %ld; max is %ld)",
2179 (long)tso->id, tso, (long)tso->stack_size, (long)tso->max_stack_size);
2181 /* If we're debugging, just print out the top of the stack */
2182 printStackChunk(tso->sp, stg_min(tso->stack+tso->stack_size,
2185 // Send this thread the StackOverflow exception
2187 throwToSingleThreaded(cap, tso, (StgClosure *)stackOverflow_closure);
2191 /* Try to double the current stack size. If that takes us over the
2192 * maximum stack size for this thread, then use the maximum instead
2193 * (that is, unless we're already at or over the max size and we
2194 * can't raise the StackOverflow exception (see above), in which
2195 * case just double the size). Finally round up so the TSO ends up as
2196 * a whole number of blocks.
2198 if (tso->stack_size >= tso->max_stack_size) {
2199 new_stack_size = tso->stack_size * 2;
2201 new_stack_size = stg_min(tso->stack_size * 2, tso->max_stack_size);
2203 new_tso_size = (lnat)BLOCK_ROUND_UP(new_stack_size * sizeof(W_) +
2204 TSO_STRUCT_SIZE)/sizeof(W_);
2205 new_tso_size = round_to_mblocks(new_tso_size); /* Be MBLOCK-friendly */
2206 new_stack_size = new_tso_size - TSO_STRUCT_SIZEW;
2208 debugTrace(DEBUG_sched,
2209 "increasing stack size from %ld words to %d.",
2210 (long)tso->stack_size, new_stack_size);
2212 dest = (StgTSO *)allocateLocal(cap,new_tso_size);
2213 TICK_ALLOC_TSO(new_stack_size,0);
2215 /* copy the TSO block and the old stack into the new area */
2216 memcpy(dest,tso,TSO_STRUCT_SIZE);
2217 stack_words = tso->stack + tso->stack_size - tso->sp;
2218 new_sp = (P_)dest + new_tso_size - stack_words;
2219 memcpy(new_sp, tso->sp, stack_words * sizeof(W_));
2221 /* relocate the stack pointers... */
2223 dest->stack_size = new_stack_size;
2225 /* Mark the old TSO as relocated. We have to check for relocated
2226 * TSOs in the garbage collector and any primops that deal with TSOs.
2228 * It's important to set the sp value to just beyond the end
2229 * of the stack, so we don't attempt to scavenge any part of the
2232 tso->what_next = ThreadRelocated;
2233 setTSOLink(cap,tso,dest);
2234 tso->sp = (P_)&(tso->stack[tso->stack_size]);
2235 tso->why_blocked = NotBlocked;
2237 IF_PAR_DEBUG(verbose,
2238 debugBelch("@@ threadStackOverflow of TSO %d (now at %p): stack size increased to %ld\n",
2239 tso->id, tso, tso->stack_size);
2240 /* If we're debugging, just print out the top of the stack */
2241 printStackChunk(tso->sp, stg_min(tso->stack+tso->stack_size,
2247 IF_DEBUG(sanity,checkTSO(dest));
2249 IF_DEBUG(scheduler,printTSO(dest));
2256 threadStackUnderflow (Task *task STG_UNUSED, StgTSO *tso)
2258 bdescr *bd, *new_bd;
2259 lnat free_w, tso_size_w;
2262 tso_size_w = tso_sizeW(tso);
2264 if (tso_size_w < MBLOCK_SIZE_W ||
2265 (nat)(tso->stack + tso->stack_size - tso->sp) > tso->stack_size / 4)
2270 // don't allow throwTo() to modify the blocked_exceptions queue
2271 // while we are moving the TSO:
2272 lockClosure((StgClosure *)tso);
2274 // this is the number of words we'll free
2275 free_w = round_to_mblocks(tso_size_w/2);
2277 bd = Bdescr((StgPtr)tso);
2278 new_bd = splitLargeBlock(bd, free_w / BLOCK_SIZE_W);
2279 bd->free = bd->start + TSO_STRUCT_SIZEW;
2281 new_tso = (StgTSO *)new_bd->start;
2282 memcpy(new_tso,tso,TSO_STRUCT_SIZE);
2283 new_tso->stack_size = new_bd->free - new_tso->stack;
2285 debugTrace(DEBUG_sched, "thread %ld: reducing TSO size from %lu words to %lu",
2286 (long)tso->id, tso_size_w, tso_sizeW(new_tso));
2288 tso->what_next = ThreadRelocated;
2289 tso->_link = new_tso; // no write barrier reqd: same generation
2291 // The TSO attached to this Task may have moved, so update the
2293 if (task->tso == tso) {
2294 task->tso = new_tso;
2300 IF_DEBUG(sanity,checkTSO(new_tso));
2305 /* ---------------------------------------------------------------------------
2307 - usually called inside a signal handler so it mustn't do anything fancy.
2308 ------------------------------------------------------------------------ */
2311 interruptStgRts(void)
2313 sched_state = SCHED_INTERRUPTING;
2314 setContextSwitches();
2318 /* -----------------------------------------------------------------------------
2321 This function causes at least one OS thread to wake up and run the
2322 scheduler loop. It is invoked when the RTS might be deadlocked, or
2323 an external event has arrived that may need servicing (eg. a
2324 keyboard interrupt).
2326 In the single-threaded RTS we don't do anything here; we only have
2327 one thread anyway, and the event that caused us to want to wake up
2328 will have interrupted any blocking system call in progress anyway.
2329 -------------------------------------------------------------------------- */
2334 #if defined(THREADED_RTS)
2335 // This forces the IO Manager thread to wakeup, which will
2336 // in turn ensure that some OS thread wakes up and runs the
2337 // scheduler loop, which will cause a GC and deadlock check.
2342 /* -----------------------------------------------------------------------------
2345 * Check the blackhole_queue for threads that can be woken up. We do
2346 * this periodically: before every GC, and whenever the run queue is
2349 * An elegant solution might be to just wake up all the blocked
2350 * threads with awakenBlockedQueue occasionally: they'll go back to
2351 * sleep again if the object is still a BLACKHOLE. Unfortunately this
2352 * doesn't give us a way to tell whether we've actually managed to
2353 * wake up any threads, so we would be busy-waiting.
2355 * -------------------------------------------------------------------------- */
2358 checkBlackHoles (Capability *cap)
2361 rtsBool any_woke_up = rtsFalse;
2364 // blackhole_queue is global:
2365 ASSERT_LOCK_HELD(&sched_mutex);
2367 debugTrace(DEBUG_sched, "checking threads blocked on black holes");
2369 // ASSUMES: sched_mutex
2370 prev = &blackhole_queue;
2371 t = blackhole_queue;
2372 while (t != END_TSO_QUEUE) {
2373 ASSERT(t->why_blocked == BlockedOnBlackHole);
2374 type = get_itbl(UNTAG_CLOSURE(t->block_info.closure))->type;
2375 if (type != BLACKHOLE && type != CAF_BLACKHOLE) {
2376 IF_DEBUG(sanity,checkTSO(t));
2377 t = unblockOne(cap, t);
2379 any_woke_up = rtsTrue;
2389 /* -----------------------------------------------------------------------------
2392 This is used for interruption (^C) and forking, and corresponds to
2393 raising an exception but without letting the thread catch the
2395 -------------------------------------------------------------------------- */
2398 deleteThread (Capability *cap, StgTSO *tso)
2400 // NOTE: must only be called on a TSO that we have exclusive
2401 // access to, because we will call throwToSingleThreaded() below.
2402 // The TSO must be on the run queue of the Capability we own, or
2403 // we must own all Capabilities.
2405 if (tso->why_blocked != BlockedOnCCall &&
2406 tso->why_blocked != BlockedOnCCall_NoUnblockExc) {
2407 throwToSingleThreaded(cap,tso,NULL);
2411 #ifdef FORKPROCESS_PRIMOP_SUPPORTED
2413 deleteThread_(Capability *cap, StgTSO *tso)
2414 { // for forkProcess only:
2415 // like deleteThread(), but we delete threads in foreign calls, too.
2417 if (tso->why_blocked == BlockedOnCCall ||
2418 tso->why_blocked == BlockedOnCCall_NoUnblockExc) {
2419 unblockOne(cap,tso);
2420 tso->what_next = ThreadKilled;
2422 deleteThread(cap,tso);
2427 /* -----------------------------------------------------------------------------
2428 raiseExceptionHelper
2430 This function is called by the raise# primitve, just so that we can
2431 move some of the tricky bits of raising an exception from C-- into
2432 C. Who knows, it might be a useful re-useable thing here too.
2433 -------------------------------------------------------------------------- */
2436 raiseExceptionHelper (StgRegTable *reg, StgTSO *tso, StgClosure *exception)
2438 Capability *cap = regTableToCapability(reg);
2439 StgThunk *raise_closure = NULL;
2441 StgRetInfoTable *info;
2443 // This closure represents the expression 'raise# E' where E
2444 // is the exception raise. It is used to overwrite all the
2445 // thunks which are currently under evaluataion.
2448 // OLD COMMENT (we don't have MIN_UPD_SIZE now):
2449 // LDV profiling: stg_raise_info has THUNK as its closure
2450 // type. Since a THUNK takes at least MIN_UPD_SIZE words in its
2451 // payload, MIN_UPD_SIZE is more approprate than 1. It seems that
2452 // 1 does not cause any problem unless profiling is performed.
2453 // However, when LDV profiling goes on, we need to linearly scan
2454 // small object pool, where raise_closure is stored, so we should
2455 // use MIN_UPD_SIZE.
2457 // raise_closure = (StgClosure *)RET_STGCALL1(P_,allocate,
2458 // sizeofW(StgClosure)+1);
2462 // Walk up the stack, looking for the catch frame. On the way,
2463 // we update any closures pointed to from update frames with the
2464 // raise closure that we just built.
2468 info = get_ret_itbl((StgClosure *)p);
2469 next = p + stack_frame_sizeW((StgClosure *)p);
2470 switch (info->i.type) {
2473 // Only create raise_closure if we need to.
2474 if (raise_closure == NULL) {
2476 (StgThunk *)allocateLocal(cap,sizeofW(StgThunk)+1);
2477 SET_HDR(raise_closure, &stg_raise_info, CCCS);
2478 raise_closure->payload[0] = exception;
2480 UPD_IND(((StgUpdateFrame *)p)->updatee,(StgClosure *)raise_closure);
2484 case ATOMICALLY_FRAME:
2485 debugTrace(DEBUG_stm, "found ATOMICALLY_FRAME at %p", p);
2487 return ATOMICALLY_FRAME;
2493 case CATCH_STM_FRAME:
2494 debugTrace(DEBUG_stm, "found CATCH_STM_FRAME at %p", p);
2496 return CATCH_STM_FRAME;
2502 case CATCH_RETRY_FRAME:
2511 /* -----------------------------------------------------------------------------
2512 findRetryFrameHelper
2514 This function is called by the retry# primitive. It traverses the stack
2515 leaving tso->sp referring to the frame which should handle the retry.
2517 This should either be a CATCH_RETRY_FRAME (if the retry# is within an orElse#)
2518 or should be a ATOMICALLY_FRAME (if the retry# reaches the top level).
2520 We skip CATCH_STM_FRAMEs (aborting and rolling back the nested tx that they
2521 create) because retries are not considered to be exceptions, despite the
2522 similar implementation.
2524 We should not expect to see CATCH_FRAME or STOP_FRAME because those should
2525 not be created within memory transactions.
2526 -------------------------------------------------------------------------- */
2529 findRetryFrameHelper (StgTSO *tso)
2532 StgRetInfoTable *info;
2536 info = get_ret_itbl((StgClosure *)p);
2537 next = p + stack_frame_sizeW((StgClosure *)p);
2538 switch (info->i.type) {
2540 case ATOMICALLY_FRAME:
2541 debugTrace(DEBUG_stm,
2542 "found ATOMICALLY_FRAME at %p during retry", p);
2544 return ATOMICALLY_FRAME;
2546 case CATCH_RETRY_FRAME:
2547 debugTrace(DEBUG_stm,
2548 "found CATCH_RETRY_FRAME at %p during retrry", p);
2550 return CATCH_RETRY_FRAME;
2552 case CATCH_STM_FRAME: {
2553 StgTRecHeader *trec = tso -> trec;
2554 StgTRecHeader *outer = stmGetEnclosingTRec(trec);
2555 debugTrace(DEBUG_stm,
2556 "found CATCH_STM_FRAME at %p during retry", p);
2557 debugTrace(DEBUG_stm, "trec=%p outer=%p", trec, outer);
2558 stmAbortTransaction(tso -> cap, trec);
2559 stmFreeAbortedTRec(tso -> cap, trec);
2560 tso -> trec = outer;
2567 ASSERT(info->i.type != CATCH_FRAME);
2568 ASSERT(info->i.type != STOP_FRAME);
2575 /* -----------------------------------------------------------------------------
2576 resurrectThreads is called after garbage collection on the list of
2577 threads found to be garbage. Each of these threads will be woken
2578 up and sent a signal: BlockedOnDeadMVar if the thread was blocked
2579 on an MVar, or NonTermination if the thread was blocked on a Black
2582 Locks: assumes we hold *all* the capabilities.
2583 -------------------------------------------------------------------------- */
2586 resurrectThreads (StgTSO *threads)
2592 for (tso = threads; tso != END_TSO_QUEUE; tso = next) {
2593 next = tso->global_link;
2595 step = Bdescr((P_)tso)->step;
2596 tso->global_link = step->threads;
2597 step->threads = tso;
2599 debugTrace(DEBUG_sched, "resurrecting thread %lu", (unsigned long)tso->id);
2601 // Wake up the thread on the Capability it was last on
2604 switch (tso->why_blocked) {
2606 case BlockedOnException:
2607 /* Called by GC - sched_mutex lock is currently held. */
2608 throwToSingleThreaded(cap, tso,
2609 (StgClosure *)blockedOnDeadMVar_closure);
2611 case BlockedOnBlackHole:
2612 throwToSingleThreaded(cap, tso,
2613 (StgClosure *)nonTermination_closure);
2616 throwToSingleThreaded(cap, tso,
2617 (StgClosure *)blockedIndefinitely_closure);
2620 /* This might happen if the thread was blocked on a black hole
2621 * belonging to a thread that we've just woken up (raiseAsync
2622 * can wake up threads, remember...).
2626 barf("resurrectThreads: thread blocked in a strange way");
2631 /* -----------------------------------------------------------------------------
2632 performPendingThrowTos is called after garbage collection, and
2633 passed a list of threads that were found to have pending throwTos
2634 (tso->blocked_exceptions was not empty), and were blocked.
2635 Normally this doesn't happen, because we would deliver the
2636 exception directly if the target thread is blocked, but there are
2637 small windows where it might occur on a multiprocessor (see
2640 NB. we must be holding all the capabilities at this point, just
2641 like resurrectThreads().
2642 -------------------------------------------------------------------------- */
2645 performPendingThrowTos (StgTSO *threads)
2651 for (tso = threads; tso != END_TSO_QUEUE; tso = next) {
2652 next = tso->global_link;
2654 step = Bdescr((P_)tso)->step;
2655 tso->global_link = step->threads;
2656 step->threads = tso;
2658 debugTrace(DEBUG_sched, "performing blocked throwTo to thread %lu", (unsigned long)tso->id);
2661 maybePerformBlockedException(cap, tso);