# HG changeset patch # User jmasa # Date 1349276932 25200 # Node ID 159131321ed4c9cc714eebd36ff4097d4f158ed9 # Parent 4271ff38528f9fbc2fdb5a7135928db3856046d2 7199349: NPG: PS: Crash seen in jprt Reviewed-by: johnc diff -r 4271ff38528f -r 159131321ed4 hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp --- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp Mon Oct 01 13:29:11 2012 +0200 +++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp Wed Oct 03 08:08:52 2012 -0700 @@ -121,103 +121,12 @@ // We get passed the space_top value to prevent us from traversing into // the old_gen promotion labs, which cannot be safely parsed. -void CardTableExtension::scavenge_contents(ObjectStartArray* start_array, - MutableSpace* sp, - HeapWord* space_top, - PSPromotionManager* pm) -{ - assert(start_array != NULL && sp != NULL && pm != NULL, "Sanity"); - assert(start_array->covered_region().contains(sp->used_region()), - "ObjectStartArray does not cover space"); - if (sp->not_empty()) { - oop* sp_top = (oop*)space_top; - oop* prev_top = NULL; - jbyte* current_card = byte_for(sp->bottom()); - jbyte* end_card = byte_for(sp_top - 1); // sp_top is exclusive - // scan card marking array - while (current_card <= end_card) { - jbyte value = *current_card; - // skip clean cards - if (card_is_clean(value)) { - current_card++; - } else { - // we found a non-clean card - jbyte* first_nonclean_card = current_card++; - oop* bottom = (oop*)addr_for(first_nonclean_card); - // find object starting on card - oop* bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom); - // bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom); - assert(bottom_obj <= bottom, "just checking"); - // make sure we don't scan oops we already looked at - if (bottom < prev_top) bottom = prev_top; - // figure out when to stop scanning - jbyte* first_clean_card; - oop* top; - bool restart_scanning; - do { - restart_scanning = false; - // find a clean card - while (current_card <= end_card) { - value = *current_card; - if (card_is_clean(value)) break; - current_card++; - } - // check if we reached the end, if so we are done - if (current_card >= end_card) { - first_clean_card = end_card + 1; - current_card++; - top = sp_top; - } else { - // we have a clean card, find object starting on that card - first_clean_card = current_card++; - top = (oop*)addr_for(first_clean_card); - oop* top_obj = (oop*)start_array->object_start((HeapWord*)top); - // top_obj = (oop*)start_array->object_start((HeapWord*)top); - assert(top_obj <= top, "just checking"); - if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { - // an arrayOop is starting on the clean card - since we do exact store - // checks for objArrays we are done - } else { - // otherwise, it is possible that the object starting on the clean card - // spans the entire card, and that the store happened on a later card. - // figure out where the object ends - top = top_obj + oop(top_obj)->size(); - jbyte* top_card = CardTableModRefBS::byte_for(top - 1); // top is exclusive - if (top_card > first_clean_card) { - // object ends a different card - current_card = top_card + 1; - if (card_is_clean(*top_card)) { - // the ending card is clean, we are done - first_clean_card = top_card; - } else { - // the ending card is not clean, continue scanning at start of do-while - restart_scanning = true; - } - } else { - // object ends on the clean card, we are done. - assert(first_clean_card == top_card, "just checking"); - } - } - } - } while (restart_scanning); - // we know which cards to scan, now clear them - while (first_nonclean_card < first_clean_card) { - *first_nonclean_card++ = clean_card; - } - // scan oops in objects - do { - oop(bottom_obj)->push_contents(pm); - bottom_obj += oop(bottom_obj)->size(); - assert(bottom_obj <= sp_top, "just checking"); - } while (bottom_obj < top); - pm->drain_stacks_cond_depth(); - // remember top oop* scanned - prev_top = top; - } - } - } -} +// Do not call this method if the space is empty. +// It is a waste to start tasks and get here only to +// do no work. If this method needs to be called +// when the space is empty, fix the calculation of +// end_card to allow sp_top == sp->bottom(). void CardTableExtension::scavenge_contents_parallel(ObjectStartArray* start_array, MutableSpace* sp, @@ -228,10 +137,11 @@ int ssize = 128; // Naked constant! Work unit = 64k. int dirty_card_count = 0; + // It is a waste to get here if empty. + assert(sp->bottom() < sp->top(), "Should not be called if empty"); oop* sp_top = (oop*)space_top; - oop* sp_last = sp->bottom() == space_top ? sp_top : sp_top - 1; jbyte* start_card = byte_for(sp->bottom()); - jbyte* end_card = byte_for(sp_last) + 1; + jbyte* end_card = byte_for(sp_top - 1) + 1; oop* last_scanned = NULL; // Prevent scanning objects more than once // The width of the stripe ssize*stripe_total must be // consistent with the number of stripes so that the complete slice @@ -255,6 +165,16 @@ HeapWord* slice_start = addr_for(worker_start_card); HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card)); +#ifdef ASSERT + if (GCWorkerDelayMillis > 0) { + // Delay 1 worker so that it proceeds after all the work + // has been completed. + if (stripe_number < 2) { + os::sleep(Thread::current(), GCWorkerDelayMillis, false); + } + } +#endif + // If there are not objects starting within the chunk, skip it. if (!start_array->object_starts_in_range(slice_start, slice_end)) { continue; diff -r 4271ff38528f -r 159131321ed4 hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.hpp --- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.hpp Mon Oct 01 13:29:11 2012 +0200 +++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.hpp Wed Oct 03 08:08:52 2012 -0700 @@ -60,11 +60,6 @@ // BarrierSet::Name kind() { return BarrierSet::CardTableExtension; } // Scavenge support - void scavenge_contents(ObjectStartArray* start_array, - MutableSpace* sp, - HeapWord* space_top, - PSPromotionManager* pm); - void scavenge_contents_parallel(ObjectStartArray* start_array, MutableSpace* sp, HeapWord* space_top, diff -r 4271ff38528f -r 159131321ed4 hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.inline.hpp --- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.inline.hpp Mon Oct 01 13:29:11 2012 +0200 +++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.inline.hpp Wed Oct 03 08:08:52 2012 -0700 @@ -136,6 +136,13 @@ HeapWord* lab_base = old_gen()->cas_allocate(OldPLABSize); if(lab_base != NULL) { +#ifdef ASSERT + // Delay the initialization of the promotion lab (plab). + // This exposes uninitialized plabs to card table processing. + if (GCWorkerDelayMillis > 0) { + os::sleep(Thread::current(), GCWorkerDelayMillis, false); + } +#endif _old_lab.initialize(MemRegion(lab_base, OldPLABSize)); // Try the old lab allocation again. new_obj = (oop) _old_lab.allocate(new_obj_size); diff -r 4271ff38528f -r 159131321ed4 hotspot/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp --- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp Mon Oct 01 13:29:11 2012 +0200 +++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp Wed Oct 03 08:08:52 2012 -0700 @@ -395,9 +395,13 @@ GCTaskQueue* q = GCTaskQueue::create(); - uint stripe_total = active_workers; - for(uint i=0; i < stripe_total; i++) { - q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); + if (!old_gen->object_space()->is_empty()) { + // There are only old-to-young pointers if there are objects + // in the old gen. + uint stripe_total = active_workers; + for(uint i=0; i < stripe_total; i++) { + q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); + } } q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); diff -r 4271ff38528f -r 159131321ed4 hotspot/src/share/vm/gc_implementation/parallelScavenge/psTasks.cpp --- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psTasks.cpp Mon Oct 01 13:29:11 2012 +0200 +++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psTasks.cpp Wed Oct 03 08:08:52 2012 -0700 @@ -165,35 +165,13 @@ } // -// SerialOldToYoungRootsTask -// - -void SerialOldToYoungRootsTask::do_it(GCTaskManager* manager, uint which) { - assert(_gen != NULL, "Sanity"); - assert(_gen->object_space()->contains(_gen_top) || _gen_top == _gen->object_space()->top(), "Sanity"); - - { - PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(which); - - assert(Universe::heap()->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); - CardTableExtension* card_table = (CardTableExtension *)Universe::heap()->barrier_set(); - // FIX ME! Assert that card_table is the type we believe it to be. - - card_table->scavenge_contents(_gen->start_array(), - _gen->object_space(), - _gen_top, - pm); - - // Do the real work - pm->drain_stacks(false); - } -} - -// // OldToYoungRootsTask // void OldToYoungRootsTask::do_it(GCTaskManager* manager, uint which) { + // There are not old-to-young pointers if the old gen is empty. + assert(!_gen->object_space()->is_empty(), + "Should not be called is there is no work"); assert(_gen != NULL, "Sanity"); assert(_gen->object_space()->contains(_gen_top) || _gen_top == _gen->object_space()->top(), "Sanity"); assert(_stripe_number < ParallelGCThreads, "Sanity"); diff -r 4271ff38528f -r 159131321ed4 hotspot/src/share/vm/gc_implementation/parallelScavenge/psTasks.hpp --- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psTasks.hpp Mon Oct 01 13:29:11 2012 +0200 +++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psTasks.hpp Wed Oct 03 08:08:52 2012 -0700 @@ -113,25 +113,6 @@ }; // -// SerialOldToYoungRootsTask -// -// This task is used to scan for roots in the perm gen - -class SerialOldToYoungRootsTask : public GCTask { - private: - PSOldGen* _gen; - HeapWord* _gen_top; - - public: - SerialOldToYoungRootsTask(PSOldGen *gen, HeapWord* gen_top) : - _gen(gen), _gen_top(gen_top) { } - - char* name() { return (char *)"serial-old-to-young-roots-task"; } - - virtual void do_it(GCTaskManager* manager, uint which); -}; - -// // OldToYoungRootsTask // // This task is used to scan old to young roots in parallel diff -r 4271ff38528f -r 159131321ed4 hotspot/src/share/vm/runtime/globals.hpp --- a/hotspot/src/share/vm/runtime/globals.hpp Mon Oct 01 13:29:11 2012 +0200 +++ b/hotspot/src/share/vm/runtime/globals.hpp Wed Oct 03 08:08:52 2012 -0700 @@ -3065,6 +3065,9 @@ develop(uintx, GCExpandToAllocateDelayMillis, 0, \ "Delay in ms between expansion and allocation") \ \ + develop(uintx, GCWorkerDelayMillis, 0, \ + "Delay in ms in scheduling GC workers") \ + \ product(intx, DeferThrSuspendLoopCount, 4000, \ "(Unstable) Number of times to iterate in safepoint loop " \ " before blocking VM threads ") \