// locking, so we don't do that.
Capability *last_free_capability;
+/* GC indicator, in scope for the scheduler, init'ed to false */
+volatile StgWord waiting_for_gc = 0;
+
#if defined(THREADED_RTS)
STATIC_INLINE rtsBool
globalWorkToDo (void)
return;
}
+ /* if waiting_for_gc was the reason to release the cap: thread
+ comes from yieldCap->releaseAndQueueWorker. Unconditionally set
+ cap. free and return (see default after the if-protected other
+ special cases). Thread will wait on cond.var and re-acquire the
+ same cap after GC (GC-triggering cap. calls releaseCap and
+ enters the spare_workers case)
+ */
+ if (waiting_for_gc) {
+ last_free_capability = cap; // needed?
+ trace(TRACE_sched | DEBUG_sched,
+ "GC pending, set capability %d free", cap->no);
+ return;
+ }
+
+
// If the next thread on the run queue is a bound thread,
// give this Capability to the appropriate Task.
if (!emptyRunQueue(cap) && cap->run_queue_hd->bound) {
// The fast path has no locking, if we don't enter this while loop
- while ( cap->returning_tasks_hd != NULL || !anyWorkForMe(cap,task) ) {
+ while ( waiting_for_gc
+ /* i.e. another capability triggered HeapOverflow, is busy
+ getting capabilities (stopping their owning tasks) */
+ || cap->returning_tasks_hd != NULL
+ /* cap reserved for another task */
+ || !anyWorkForMe(cap,task)
+ /* cap/task have no work */
+ ) {
debugTrace(DEBUG_sched, "giving up capability %d", cap->no);
// We must now release the capability and wait to be woken up
* ------------------------------------------------------------------------- */
void
-shutdownCapability (Capability *cap, Task *task)
+shutdownCapability (Capability *cap, Task *task, rtsBool safe)
{
nat i;
for (t = cap->spare_workers; t != NULL; t = t->next) {
if (!osThreadIsAlive(t->id)) {
debugTrace(DEBUG_sched,
- "worker thread %p has died unexpectedly", t->id);
+ "worker thread %p has died unexpectedly", (void *)t->id);
if (!prev) {
cap->spare_workers = t->next;
} else {
yieldThread();
continue;
}
+
+ // If "safe", then busy-wait for any threads currently doing
+ // foreign calls. If we're about to unload this DLL, for
+ // example, we need to be sure that there are no OS threads
+ // that will try to return to code that has been unloaded.
+ // We can be a bit more relaxed when this is a standalone
+ // program that is about to terminate, and let safe=false.
+ if (cap->suspended_ccalling_tasks && safe) {
+ debugTrace(DEBUG_sched,
+ "thread(s) are involved in foreign calls, yielding");
+ cap->running_task = NULL;
+ RELEASE_LOCK(&cap->lock);
+ yieldThread();
+ continue;
+ }
+
debugTrace(DEBUG_sched, "capability %d is stopped.", cap->no);
- freeCapability(cap);
+ freeCapability(cap);
RELEASE_LOCK(&cap->lock);
break;
}
#endif
}
+/* ---------------------------------------------------------------------------
+ Mark everything directly reachable from the Capabilities. When
+ using multiple GC threads, each GC thread marks all Capabilities
+ for which (c `mod` n == 0), for Capability c and thread n.
+ ------------------------------------------------------------------------ */
+
+void
+markSomeCapabilities (evac_fn evac, void *user, nat i0, nat delta)
+{
+ nat i;
+ Capability *cap;
+ Task *task;
+
+ // Each GC thread is responsible for following roots from the
+ // Capability of the same number. There will usually be the same
+ // or fewer Capabilities as GC threads, but just in case there
+ // are more, we mark every Capability whose number is the GC
+ // thread's index plus a multiple of the number of GC threads.
+ for (i = i0; i < n_capabilities; i += delta) {
+ cap = &capabilities[i];
+ evac(user, (StgClosure **)(void *)&cap->run_queue_hd);
+ evac(user, (StgClosure **)(void *)&cap->run_queue_tl);
+#if defined(THREADED_RTS)
+ evac(user, (StgClosure **)(void *)&cap->wakeup_queue_hd);
+ evac(user, (StgClosure **)(void *)&cap->wakeup_queue_tl);
+#endif
+ for (task = cap->suspended_ccalling_tasks; task != NULL;
+ task=task->next) {
+ debugTrace(DEBUG_sched,
+ "evac'ing suspended TSO %lu", (unsigned long)task->suspended_tso->id);
+ evac(user, (StgClosure **)(void *)&task->suspended_tso);
+ }
+
+#if defined(THREADED_RTS)
+ markSparkQueue (evac, user, cap);
+#endif
+ }
+
+#if !defined(THREADED_RTS)
+ evac(user, (StgClosure **)(void *)&blocked_queue_hd);
+ evac(user, (StgClosure **)(void *)&blocked_queue_tl);
+ evac(user, (StgClosure **)(void *)&sleeping_queue);
+#endif
+}
+
+// This function is used by the compacting GC to thread all the
+// pointers from spark queues.
+void
+traverseSparkQueues (evac_fn evac USED_IF_THREADS, void *user USED_IF_THREADS)
+{
+#if defined(THREADED_RTS)
+ nat i;
+ for (i = 0; i < n_capabilities; i++) {
+ traverseSparkQueue (evac, user, &capabilities[i]);
+ }
+#endif // THREADED_RTS
+
+}
+
+void
+markCapabilities (evac_fn evac, void *user)
+{
+ markSomeCapabilities(evac, user, 0, 1);
+}
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