--- a/hotspot/src/share/vm/gc/cms/concurrentMarkSweepGeneration.cpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/gc/cms/concurrentMarkSweepGeneration.cpp Fri Jul 29 20:23:24 2016 +0000
@@ -2888,7 +2888,10 @@
CMSParInitialMarkTask tsk(this, &srs, n_workers);
initialize_sequential_subtasks_for_young_gen_rescan(n_workers);
- if (n_workers > 1) {
+ // If the total workers is greater than 1, then multiple workers
+ // may be used at some time and the initialization has been set
+ // such that the single threaded path cannot be used.
+ if (workers->total_workers() > 1) {
workers->run_task(&tsk);
} else {
tsk.work(0);
@@ -3507,7 +3510,7 @@
uint num_workers = AdaptiveSizePolicy::calc_active_conc_workers(conc_workers()->total_workers(),
conc_workers()->active_workers(),
Threads::number_of_non_daemon_threads());
- conc_workers()->set_active_workers(num_workers);
+ num_workers = conc_workers()->update_active_workers(num_workers);
CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace();
--- a/hotspot/src/share/vm/gc/cms/parNewGeneration.cpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/gc/cms/parNewGeneration.cpp Fri Jul 29 20:23:24 2016 +0000
@@ -898,7 +898,7 @@
AdaptiveSizePolicy::calc_active_workers(workers->total_workers(),
workers->active_workers(),
Threads::number_of_non_daemon_threads());
- workers->set_active_workers(active_workers);
+ active_workers = workers->update_active_workers(active_workers);
_old_gen = gch->old_gen();
// If the next generation is too full to accommodate worst-case promotion
@@ -952,7 +952,9 @@
// separate thread causes wide variance in run times. We can't help this
// in the multi-threaded case, but we special-case n=1 here to get
// repeatable measurements of the 1-thread overhead of the parallel code.
- if (active_workers > 1) {
+ // Might multiple workers ever be used? If yes, initialization
+ // has been done such that the single threaded path should not be used.
+ if (workers->total_workers() > 1) {
workers->run_task(&tsk);
} else {
tsk.work(0);
--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp Fri Jul 29 20:23:24 2016 +0000
@@ -1331,7 +1331,7 @@
AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
workers()->active_workers(),
Threads::number_of_non_daemon_threads());
- workers()->set_active_workers(n_workers);
+ workers()->update_active_workers(n_workers);
ParRebuildRSTask rebuild_rs_task(this);
workers()->run_task(&rebuild_rs_task);
@@ -3067,7 +3067,7 @@
uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
workers()->active_workers(),
Threads::number_of_non_daemon_threads());
- workers()->set_active_workers(active_workers);
+ workers()->update_active_workers(active_workers);
TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
--- a/hotspot/src/share/vm/gc/g1/g1ConcurrentMark.cpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/gc/g1/g1ConcurrentMark.cpp Fri Jul 29 20:23:24 2016 +0000
@@ -1031,11 +1031,14 @@
uint active_workers = MAX2(1U, parallel_marking_threads());
assert(active_workers > 0, "Should have been set");
+ // Setting active workers is not guaranteed since fewer
+ // worker threads may currently exist and more may not be
+ // available.
+ active_workers = _parallel_workers->update_active_workers(active_workers);
// Parallel task terminator is set in "set_concurrency_and_phase()"
set_concurrency_and_phase(active_workers, true /* concurrent */);
G1CMConcurrentMarkingTask markingTask(this, cmThread());
- _parallel_workers->set_active_workers(active_workers);
_parallel_workers->run_task(&markingTask);
print_stats();
}
--- a/hotspot/src/share/vm/gc/parallel/gcTaskManager.cpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/gc/parallel/gcTaskManager.cpp Fri Jul 29 20:23:24 2016 +0000
@@ -537,7 +537,7 @@
created_workers() - active_workers() - idle_workers();
if (more_inactive_workers < 0) {
int reduced_active_workers = active_workers() + more_inactive_workers;
- set_active_workers(reduced_active_workers);
+ update_active_workers(reduced_active_workers);
more_inactive_workers = 0;
}
log_trace(gc, task)("JT: %d workers %d active %d idle %d more %d",
--- a/hotspot/src/share/vm/gc/parallel/gcTaskManager.hpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/gc/parallel/gcTaskManager.hpp Fri Jul 29 20:23:24 2016 +0000
@@ -457,11 +457,12 @@
uint workers() const {
return _workers;
}
- void set_active_workers(uint v) {
+ uint update_active_workers(uint v) {
assert(v <= _workers, "Trying to set more workers active than there are");
_active_workers = MIN2(v, _workers);
assert(v != 0, "Trying to set active workers to 0");
_active_workers = MAX2(1U, _active_workers);
+ return _active_workers;
}
// Sets the number of threads that will be used in a collection
void set_active_gang();
--- a/hotspot/src/share/vm/gc/parallel/psScavenge.cpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/gc/parallel/psScavenge.cpp Fri Jul 29 20:23:24 2016 +0000
@@ -391,11 +391,15 @@
ParallelTaskTerminator terminator(
active_workers,
(TaskQueueSetSuper*) promotion_manager->stack_array_depth());
- if (active_workers > 1) {
- for (uint j = 0; j < active_workers; j++) {
- q->enqueue(new StealTask(&terminator));
+ // If active_workers can exceed 1, add a StrealTask.
+ // PSPromotionManager::drain_stacks_depth() does not fully drain its
+ // stacks and expects a StealTask to complete the draining if
+ // ParallelGCThreads is > 1.
+ if (gc_task_manager()->workers() > 1) {
+ for (uint j = 0; j < active_workers; j++) {
+ q->enqueue(new StealTask(&terminator));
+ }
}
- }
gc_task_manager()->execute_and_wait(q);
}
--- a/hotspot/src/share/vm/gc/shared/workerManager.hpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/gc/shared/workerManager.hpp Fri Jul 29 20:23:24 2016 +0000
@@ -55,18 +55,29 @@
uint start = created_workers;
uint end = MIN2(active_workers, total_workers);
for (uint worker_id = start; worker_id < end; worker_id += 1) {
- WorkerThread* new_worker = holder->install_worker(worker_id);
- assert(new_worker != NULL, "Failed to allocate GangWorker");
+ WorkerThread* new_worker = NULL;
+ if (initializing || !InjectGCWorkerCreationFailure) {
+ new_worker = holder->install_worker(worker_id);
+ }
if (new_worker == NULL || !os::create_thread(new_worker, worker_type)) {
+ log_trace(gc, task)("WorkerManager::add_workers() : "
+ "creation failed due to failed allocation of native %s",
+ new_worker == NULL ? "memory" : "thread");
+ if (new_worker != NULL) {
+ delete new_worker;
+ }
if (initializing) {
- vm_exit_out_of_memory(0, OOM_MALLOC_ERROR,
- "Cannot create worker GC thread. Out of system resources.");
+ vm_exit_out_of_memory(0, OOM_MALLOC_ERROR, "Cannot create worker GC thread. Out of system resources.");
}
+ break;
}
created_workers++;
os::start_thread(new_worker);
}
+ log_trace(gc, task)("WorkerManager::add_workers() : "
+ "created_workers: %u", created_workers);
+
return created_workers;
}
--- a/hotspot/src/share/vm/gc/shared/workgroup.cpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/gc/shared/workgroup.cpp Fri Jul 29 20:23:24 2016 +0000
@@ -274,8 +274,10 @@
"Trying to execute task %s with %u workers which is more than the amount of total workers %u.",
task->name(), num_workers, total_workers());
guarantee(num_workers > 0, "Trying to execute task %s with zero workers", task->name());
- add_workers(num_workers, false);
+ uint old_num_workers = _active_workers;
+ update_active_workers(num_workers);
_dispatcher->coordinator_execute_on_workers(task, num_workers);
+ update_active_workers(old_num_workers);
}
AbstractGangWorker::AbstractGangWorker(AbstractWorkGang* gang, uint id) {
--- a/hotspot/src/share/vm/gc/shared/workgroup.hpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/gc/shared/workgroup.hpp Fri Jul 29 20:23:24 2016 +0000
@@ -156,15 +156,14 @@
return _active_workers;
}
- void set_active_workers(uint v) {
+ uint update_active_workers(uint v) {
assert(v <= _total_workers,
"Trying to set more workers active than there are");
_active_workers = MIN2(v, _total_workers);
add_workers(false /* exit_on_failure */);
assert(v != 0, "Trying to set active workers to 0");
- assert(UseDynamicNumberOfGCThreads || _active_workers == _total_workers,
- "Unless dynamic should use total workers");
log_info(gc, task)("GC Workers: using %d out of %d", _active_workers, _total_workers);
+ return _active_workers;
}
// Add GC workers as needed.
--- a/hotspot/src/share/vm/runtime/globals.hpp Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/src/share/vm/runtime/globals.hpp Fri Jul 29 20:23:24 2016 +0000
@@ -1438,6 +1438,10 @@
"Dynamically choose the number of parallel threads " \
"parallel gc will use") \
\
+ diagnostic(bool, InjectGCWorkerCreationFailure, false, \
+ "Inject thread creation failures for " \
+ "UseDynamicNumberOfGCThreads") \
+ \
diagnostic(bool, ForceDynamicNumberOfGCThreads, false, \
"Force dynamic selection of the number of " \
"parallel threads parallel gc will use to aid debugging") \
--- a/hotspot/test/gc/stress/TestGCOld.java Fri Jul 29 11:38:07 2016 -0700
+++ b/hotspot/test/gc/stress/TestGCOld.java Fri Jul 29 20:23:24 2016 +0000
@@ -1,5 +1,5 @@
/*
-* Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+* Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -33,6 +33,7 @@
* @run main/othervm -Xmx384M -XX:+UseConcMarkSweepGC TestGCOld 50 1 20 10 10000
* @run main/othervm -Xmx384M -XX:+UseG1GC TestGCOld 50 1 20 10 10000
* @run main/othervm -Xms64m -Xmx128m -XX:+UseG1GC -XX:+UseDynamicNumberOfGCThreads -Xlog:gc,gc+task=trace TestGCOld 50 5 20 1 5000
+ * @run main/othervm -Xms64m -Xmx128m -XX:+UseG1GC -XX:+UseDynamicNumberOfGCThreads -XX:+UnlockDiagnosticVMOptions -XX:+InjectGCWorkerCreationFailure -Xlog:gc,gc+task=trace TestGCOld 50 5 20 1 5000
*/
import java.text.*;