--- a/hotspot/src/share/vm/utilities/workgroup.cpp Wed Jun 04 13:51:09 2008 -0700
+++ b/hotspot/src/share/vm/utilities/workgroup.cpp Thu Jun 05 15:57:56 2008 -0700
@@ -28,13 +28,19 @@
// Definitions of WorkGang methods.
AbstractWorkGang::AbstractWorkGang(const char* name,
- bool are_GC_threads) :
+ bool are_GC_task_threads,
+ bool are_ConcurrentGC_threads) :
_name(name),
- _are_GC_threads(are_GC_threads) {
+ _are_GC_task_threads(are_GC_task_threads),
+ _are_ConcurrentGC_threads(are_ConcurrentGC_threads) {
+
+ assert(!(are_GC_task_threads && are_ConcurrentGC_threads),
+ "They cannot both be STW GC and Concurrent threads" );
+
// Other initialization.
_monitor = new Monitor(/* priority */ Mutex::leaf,
/* name */ "WorkGroup monitor",
- /* allow_vm_block */ are_GC_threads);
+ /* allow_vm_block */ are_GC_task_threads);
assert(monitor() != NULL, "Failed to allocate monitor");
_terminate = false;
_task = NULL;
@@ -44,16 +50,21 @@
}
WorkGang::WorkGang(const char* name,
- int workers,
- bool are_GC_threads) :
- AbstractWorkGang(name, are_GC_threads) {
+ int workers,
+ bool are_GC_task_threads,
+ bool are_ConcurrentGC_threads) :
+ AbstractWorkGang(name, are_GC_task_threads, are_ConcurrentGC_threads)
+{
// Save arguments.
_total_workers = workers;
+
if (TraceWorkGang) {
tty->print_cr("Constructing work gang %s with %d threads", name, workers);
}
_gang_workers = NEW_C_HEAP_ARRAY(GangWorker*, workers);
- assert(gang_workers() != NULL, "Failed to allocate gang workers");
+ if (gang_workers() == NULL) {
+ vm_exit_out_of_memory(0, "Cannot create GangWorker array.");
+ }
for (int worker = 0; worker < total_workers(); worker += 1) {
GangWorker* new_worker = new GangWorker(this, worker);
assert(new_worker != NULL, "Failed to allocate GangWorker");
@@ -285,7 +296,11 @@
}
bool GangWorker::is_GC_task_thread() const {
- return gang()->are_GC_threads();
+ return gang()->are_GC_task_threads();
+}
+
+bool GangWorker::is_ConcurrentGC_thread() const {
+ return gang()->are_ConcurrentGC_threads();
}
void GangWorker::print_on(outputStream* st) const {
@@ -312,26 +327,43 @@
WorkGangBarrierSync::WorkGangBarrierSync()
: _monitor(Mutex::safepoint, "work gang barrier sync", true),
- _n_workers(0), _n_completed(0) {
+ _n_workers(0), _n_completed(0), _should_reset(false) {
}
WorkGangBarrierSync::WorkGangBarrierSync(int n_workers, const char* name)
: _monitor(Mutex::safepoint, name, true),
- _n_workers(n_workers), _n_completed(0) {
+ _n_workers(n_workers), _n_completed(0), _should_reset(false) {
}
void WorkGangBarrierSync::set_n_workers(int n_workers) {
_n_workers = n_workers;
_n_completed = 0;
+ _should_reset = false;
}
void WorkGangBarrierSync::enter() {
MutexLockerEx x(monitor(), Mutex::_no_safepoint_check_flag);
+ if (should_reset()) {
+ // The should_reset() was set and we are the first worker to enter
+ // the sync barrier. We will zero the n_completed() count which
+ // effectively resets the barrier.
+ zero_completed();
+ set_should_reset(false);
+ }
inc_completed();
if (n_completed() == n_workers()) {
+ // At this point we would like to reset the barrier to be ready in
+ // case it is used again. However, we cannot set n_completed() to
+ // 0, even after the notify_all(), given that some other workers
+ // might still be waiting for n_completed() to become ==
+ // n_workers(). So, if we set n_completed() to 0, those workers
+ // will get stuck (as they will wake up, see that n_completed() !=
+ // n_workers() and go back to sleep). Instead, we raise the
+ // should_reset() flag and the barrier will be reset the first
+ // time a worker enters it again.
+ set_should_reset(true);
monitor()->notify_all();
- }
- else {
+ } else {
while (n_completed() != n_workers()) {
monitor()->wait(/* no_safepoint_check */ true);
}
@@ -442,3 +474,122 @@
}
return false;
}
+
+bool FreeIdSet::_stat_init = false;
+FreeIdSet* FreeIdSet::_sets[NSets];
+bool FreeIdSet::_safepoint;
+
+FreeIdSet::FreeIdSet(int sz, Monitor* mon) :
+ _sz(sz), _mon(mon), _hd(0), _waiters(0), _index(-1), _claimed(0)
+{
+ _ids = new int[sz];
+ for (int i = 0; i < sz; i++) _ids[i] = i+1;
+ _ids[sz-1] = end_of_list; // end of list.
+ if (_stat_init) {
+ for (int j = 0; j < NSets; j++) _sets[j] = NULL;
+ _stat_init = true;
+ }
+ // Add to sets. (This should happen while the system is still single-threaded.)
+ for (int j = 0; j < NSets; j++) {
+ if (_sets[j] == NULL) {
+ _sets[j] = this;
+ _index = j;
+ break;
+ }
+ }
+ guarantee(_index != -1, "Too many FreeIdSets in use!");
+}
+
+FreeIdSet::~FreeIdSet() {
+ _sets[_index] = NULL;
+}
+
+void FreeIdSet::set_safepoint(bool b) {
+ _safepoint = b;
+ if (b) {
+ for (int j = 0; j < NSets; j++) {
+ if (_sets[j] != NULL && _sets[j]->_waiters > 0) {
+ Monitor* mon = _sets[j]->_mon;
+ mon->lock_without_safepoint_check();
+ mon->notify_all();
+ mon->unlock();
+ }
+ }
+ }
+}
+
+#define FID_STATS 0
+
+int FreeIdSet::claim_par_id() {
+#if FID_STATS
+ thread_t tslf = thr_self();
+ tty->print("claim_par_id[%d]: sz = %d, claimed = %d\n", tslf, _sz, _claimed);
+#endif
+ MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
+ while (!_safepoint && _hd == end_of_list) {
+ _waiters++;
+#if FID_STATS
+ if (_waiters > 5) {
+ tty->print("claim_par_id waiting[%d]: %d waiters, %d claimed.\n",
+ tslf, _waiters, _claimed);
+ }
+#endif
+ _mon->wait(Mutex::_no_safepoint_check_flag);
+ _waiters--;
+ }
+ if (_hd == end_of_list) {
+#if FID_STATS
+ tty->print("claim_par_id[%d]: returning EOL.\n", tslf);
+#endif
+ return -1;
+ } else {
+ int res = _hd;
+ _hd = _ids[res];
+ _ids[res] = claimed; // For debugging.
+ _claimed++;
+#if FID_STATS
+ tty->print("claim_par_id[%d]: returning %d, claimed = %d.\n",
+ tslf, res, _claimed);
+#endif
+ return res;
+ }
+}
+
+bool FreeIdSet::claim_perm_id(int i) {
+ assert(0 <= i && i < _sz, "Out of range.");
+ MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
+ int prev = end_of_list;
+ int cur = _hd;
+ while (cur != end_of_list) {
+ if (cur == i) {
+ if (prev == end_of_list) {
+ _hd = _ids[cur];
+ } else {
+ _ids[prev] = _ids[cur];
+ }
+ _ids[cur] = claimed;
+ _claimed++;
+ return true;
+ } else {
+ prev = cur;
+ cur = _ids[cur];
+ }
+ }
+ return false;
+
+}
+
+void FreeIdSet::release_par_id(int id) {
+ MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
+ assert(_ids[id] == claimed, "Precondition.");
+ _ids[id] = _hd;
+ _hd = id;
+ _claimed--;
+#if FID_STATS
+ tty->print("[%d] release_par_id(%d), waiters =%d, claimed = %d.\n",
+ thr_self(), id, _waiters, _claimed);
+#endif
+ if (_waiters > 0)
+ // Notify all would be safer, but this is OK, right?
+ _mon->notify_all();
+}