diff -r 455328d90876 -r abdfc822206f src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp --- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp Tue Mar 29 22:36:16 2011 -0400 +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp Wed Mar 30 10:26:59 2011 -0400 @@ -28,6 +28,7 @@ #include "gc_implementation/g1/concurrentG1Refine.hpp" #include "gc_implementation/g1/concurrentG1RefineThread.hpp" #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" +#include "gc_implementation/g1/g1AllocRegion.inline.hpp" #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" #include "gc_implementation/g1/g1CollectorPolicy.hpp" #include "gc_implementation/g1/g1MarkSweep.hpp" @@ -517,8 +518,7 @@ return NULL; } -HeapRegion* G1CollectedHeap::new_region_work(size_t word_size, - bool do_expand) { +HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) { assert(!isHumongous(word_size) || word_size <= (size_t) HeapRegion::GrainWords, "the only time we use this to allocate a humongous region is " @@ -566,7 +566,7 @@ size_t word_size) { HeapRegion* alloc_region = NULL; if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) { - alloc_region = new_region_work(word_size, true /* do_expand */); + alloc_region = new_region(word_size, true /* do_expand */); if (purpose == GCAllocForSurvived && alloc_region != NULL) { alloc_region->set_survivor(); } @@ -587,7 +587,7 @@ // Only one region to allocate, no need to go through the slower // path. The caller will attempt the expasion if this fails, so // let's not try to expand here too. - HeapRegion* hr = new_region_work(word_size, false /* do_expand */); + HeapRegion* hr = new_region(word_size, false /* do_expand */); if (hr != NULL) { first = hr->hrs_index(); } else { @@ -788,407 +788,12 @@ return result; } -void -G1CollectedHeap::retire_cur_alloc_region(HeapRegion* cur_alloc_region) { - // Other threads might still be trying to allocate using CASes out - // of the region we are retiring, as they can do so without holding - // the Heap_lock. So we first have to make sure that noone else can - // allocate in it by doing a maximal allocation. Even if our CAS - // attempt fails a few times, we'll succeed sooner or later given - // that a failed CAS attempt mean that the region is getting closed - // to being full (someone else succeeded in allocating into it). - size_t free_word_size = cur_alloc_region->free() / HeapWordSize; - - // This is the minimum free chunk we can turn into a dummy - // object. If the free space falls below this, then noone can - // allocate in this region anyway (all allocation requests will be - // of a size larger than this) so we won't have to perform the dummy - // allocation. - size_t min_word_size_to_fill = CollectedHeap::min_fill_size(); - - while (free_word_size >= min_word_size_to_fill) { - HeapWord* dummy = - cur_alloc_region->par_allocate_no_bot_updates(free_word_size); - if (dummy != NULL) { - // If the allocation was successful we should fill in the space. - CollectedHeap::fill_with_object(dummy, free_word_size); - break; - } - - free_word_size = cur_alloc_region->free() / HeapWordSize; - // It's also possible that someone else beats us to the - // allocation and they fill up the region. In that case, we can - // just get out of the loop - } - assert(cur_alloc_region->free() / HeapWordSize < min_word_size_to_fill, - "sanity"); - - retire_cur_alloc_region_common(cur_alloc_region); - assert(_cur_alloc_region == NULL, "post-condition"); -} - -// See the comment in the .hpp file about the locking protocol and -// assumptions of this method (and other related ones). -HeapWord* -G1CollectedHeap::replace_cur_alloc_region_and_allocate(size_t word_size, - bool at_safepoint, - bool do_dirtying, - bool can_expand) { - assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); - assert(_cur_alloc_region == NULL, - "replace_cur_alloc_region_and_allocate() should only be called " - "after retiring the previous current alloc region"); - assert(SafepointSynchronize::is_at_safepoint() == at_safepoint, - "at_safepoint and is_at_safepoint() should be a tautology"); - assert(!can_expand || g1_policy()->can_expand_young_list(), - "we should not call this method with can_expand == true if " - "we are not allowed to expand the young gen"); - - if (can_expand || !g1_policy()->is_young_list_full()) { - HeapRegion* new_cur_alloc_region = new_alloc_region(word_size); - if (new_cur_alloc_region != NULL) { - assert(new_cur_alloc_region->is_empty(), - "the newly-allocated region should be empty, " - "as right now we only allocate new regions out of the free list"); - g1_policy()->update_region_num(true /* next_is_young */); - set_region_short_lived_locked(new_cur_alloc_region); - - assert(!new_cur_alloc_region->isHumongous(), - "Catch a regression of this bug."); - - // We need to ensure that the stores to _cur_alloc_region and, - // subsequently, to top do not float above the setting of the - // young type. - OrderAccess::storestore(); - - // Now, perform the allocation out of the region we just - // allocated. Note that noone else can access that region at - // this point (as _cur_alloc_region has not been updated yet), - // so we can just go ahead and do the allocation without any - // atomics (and we expect this allocation attempt to - // suceeded). Given that other threads can attempt an allocation - // with a CAS and without needing the Heap_lock, if we assigned - // the new region to _cur_alloc_region before first allocating - // into it other threads might have filled up the new region - // before we got a chance to do the allocation ourselves. In - // that case, we would have needed to retire the region, grab a - // new one, and go through all this again. Allocating out of the - // new region before assigning it to _cur_alloc_region avoids - // all this. - HeapWord* result = - new_cur_alloc_region->allocate_no_bot_updates(word_size); - assert(result != NULL, "we just allocate out of an empty region " - "so allocation should have been successful"); - assert(is_in(result), "result should be in the heap"); - - // Now make sure that the store to _cur_alloc_region does not - // float above the store to top. - OrderAccess::storestore(); - _cur_alloc_region = new_cur_alloc_region; - - if (!at_safepoint) { - Heap_lock->unlock(); - } - - // do the dirtying, if necessary, after we release the Heap_lock - if (do_dirtying) { - dirty_young_block(result, word_size); - } - return result; - } - } - - assert(_cur_alloc_region == NULL, "we failed to allocate a new current " - "alloc region, it should still be NULL"); - assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); - return NULL; -} - -// See the comment in the .hpp file about the locking protocol and -// assumptions of this method (and other related ones). -HeapWord* -G1CollectedHeap::attempt_allocation_slow(size_t word_size) { - assert_heap_locked_and_not_at_safepoint(); - assert(!isHumongous(word_size), "attempt_allocation_slow() should not be " - "used for humongous allocations"); - - // We should only reach here when we were unable to allocate - // otherwise. So, we should have not active current alloc region. - assert(_cur_alloc_region == NULL, "current alloc region should be NULL"); - - // We will loop while succeeded is false, which means that we tried - // to do a collection, but the VM op did not succeed. So, when we - // exit the loop, either one of the allocation attempts was - // successful, or we succeeded in doing the VM op but which was - // unable to allocate after the collection. - for (int try_count = 1; /* we'll return or break */; try_count += 1) { - bool succeeded = true; - - // Every time we go round the loop we should be holding the Heap_lock. - assert_heap_locked(); - - if (GC_locker::is_active_and_needs_gc()) { - // We are locked out of GC because of the GC locker. We can - // allocate a new region only if we can expand the young gen. - - if (g1_policy()->can_expand_young_list()) { - // Yes, we are allowed to expand the young gen. Let's try to - // allocate a new current alloc region. - HeapWord* result = - replace_cur_alloc_region_and_allocate(word_size, - false, /* at_safepoint */ - true, /* do_dirtying */ - true /* can_expand */); - if (result != NULL) { - assert_heap_not_locked(); - return result; - } - } - // We could not expand the young gen further (or we could but we - // failed to allocate a new region). We'll stall until the GC - // locker forces a GC. - - // If this thread is not in a jni critical section, we stall - // the requestor until the critical section has cleared and - // GC allowed. When the critical section clears, a GC is - // initiated by the last thread exiting the critical section; so - // we retry the allocation sequence from the beginning of the loop, - // rather than causing more, now probably unnecessary, GC attempts. - JavaThread* jthr = JavaThread::current(); - assert(jthr != NULL, "sanity"); - if (jthr->in_critical()) { - if (CheckJNICalls) { - fatal("Possible deadlock due to allocating while" - " in jni critical section"); - } - // We are returning NULL so the protocol is that we're still - // holding the Heap_lock. - assert_heap_locked(); - return NULL; - } - - Heap_lock->unlock(); - GC_locker::stall_until_clear(); - - // No need to relock the Heap_lock. We'll fall off to the code - // below the else-statement which assumes that we are not - // holding the Heap_lock. - } else { - // We are not locked out. So, let's try to do a GC. The VM op - // will retry the allocation before it completes. - - // Read the GC count while holding the Heap_lock - unsigned int gc_count_before = SharedHeap::heap()->total_collections(); - - Heap_lock->unlock(); - - HeapWord* result = - do_collection_pause(word_size, gc_count_before, &succeeded); - assert_heap_not_locked(); - if (result != NULL) { - assert(succeeded, "the VM op should have succeeded"); - - // Allocations that take place on VM operations do not do any - // card dirtying and we have to do it here. - dirty_young_block(result, word_size); - return result; - } - } - - // Both paths that get us here from above unlock the Heap_lock. - assert_heap_not_locked(); - - // We can reach here when we were unsuccessful in doing a GC, - // because another thread beat us to it, or because we were locked - // out of GC due to the GC locker. In either case a new alloc - // region might be available so we will retry the allocation. - HeapWord* result = attempt_allocation(word_size); - if (result != NULL) { - assert_heap_not_locked(); - return result; - } - - // So far our attempts to allocate failed. The only time we'll go - // around the loop and try again is if we tried to do a GC and the - // VM op that we tried to schedule was not successful because - // another thread beat us to it. If that happened it's possible - // that by the time we grabbed the Heap_lock again and tried to - // allocate other threads filled up the young generation, which - // means that the allocation attempt after the GC also failed. So, - // it's worth trying to schedule another GC pause. - if (succeeded) { - break; - } - - // Give a warning if we seem to be looping forever. - if ((QueuedAllocationWarningCount > 0) && - (try_count % QueuedAllocationWarningCount == 0)) { - warning("G1CollectedHeap::attempt_allocation_slow() " - "retries %d times", try_count); - } - } - - assert_heap_locked(); - return NULL; -} - -// See the comment in the .hpp file about the locking protocol and -// assumptions of this method (and other related ones). -HeapWord* -G1CollectedHeap::attempt_allocation_humongous(size_t word_size, - bool at_safepoint) { - // This is the method that will allocate a humongous object. All - // allocation paths that attempt to allocate a humongous object - // should eventually reach here. Currently, the only paths are from - // mem_allocate() and attempt_allocation_at_safepoint(). - assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); - assert(isHumongous(word_size), "attempt_allocation_humongous() " - "should only be used for humongous allocations"); - assert(SafepointSynchronize::is_at_safepoint() == at_safepoint, - "at_safepoint and is_at_safepoint() should be a tautology"); - - HeapWord* result = NULL; - - // We will loop while succeeded is false, which means that we tried - // to do a collection, but the VM op did not succeed. So, when we - // exit the loop, either one of the allocation attempts was - // successful, or we succeeded in doing the VM op but which was - // unable to allocate after the collection. - for (int try_count = 1; /* we'll return or break */; try_count += 1) { - bool succeeded = true; - - // Given that humongous objects are not allocated in young - // regions, we'll first try to do the allocation without doing a - // collection hoping that there's enough space in the heap. - result = humongous_obj_allocate(word_size); - assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(), - "catch a regression of this bug."); - if (result != NULL) { - if (!at_safepoint) { - // If we're not at a safepoint, unlock the Heap_lock. - Heap_lock->unlock(); - } - return result; - } - - // If we failed to allocate the humongous object, we should try to - // do a collection pause (if we're allowed) in case it reclaims - // enough space for the allocation to succeed after the pause. - if (!at_safepoint) { - // Read the GC count while holding the Heap_lock - unsigned int gc_count_before = SharedHeap::heap()->total_collections(); - - // If we're allowed to do a collection we're not at a - // safepoint, so it is safe to unlock the Heap_lock. - Heap_lock->unlock(); - - result = do_collection_pause(word_size, gc_count_before, &succeeded); - assert_heap_not_locked(); - if (result != NULL) { - assert(succeeded, "the VM op should have succeeded"); - return result; - } - - // If we get here, the VM operation either did not succeed - // (i.e., another thread beat us to it) or it succeeded but - // failed to allocate the object. - - // If we're allowed to do a collection we're not at a - // safepoint, so it is safe to lock the Heap_lock. - Heap_lock->lock(); - } - - assert(result == NULL, "otherwise we should have exited the loop earlier"); - - // So far our attempts to allocate failed. The only time we'll go - // around the loop and try again is if we tried to do a GC and the - // VM op that we tried to schedule was not successful because - // another thread beat us to it. That way it's possible that some - // space was freed up by the thread that successfully scheduled a - // GC. So it's worth trying to allocate again. - if (succeeded) { - break; - } - - // Give a warning if we seem to be looping forever. - if ((QueuedAllocationWarningCount > 0) && - (try_count % QueuedAllocationWarningCount == 0)) { - warning("G1CollectedHeap::attempt_allocation_humongous " - "retries %d times", try_count); - } - } - - assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); - return NULL; -} - -HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, - bool expect_null_cur_alloc_region) { - assert_at_safepoint(true /* should_be_vm_thread */); - assert(_cur_alloc_region == NULL || !expect_null_cur_alloc_region, - err_msg("the current alloc region was unexpectedly found " - "to be non-NULL, cur alloc region: "PTR_FORMAT" " - "expect_null_cur_alloc_region: %d word_size: "SIZE_FORMAT, - _cur_alloc_region, expect_null_cur_alloc_region, word_size)); - - if (!isHumongous(word_size)) { - if (!expect_null_cur_alloc_region) { - HeapRegion* cur_alloc_region = _cur_alloc_region; - if (cur_alloc_region != NULL) { - // We are at a safepoint so no reason to use the MT-safe version. - HeapWord* result = cur_alloc_region->allocate_no_bot_updates(word_size); - if (result != NULL) { - assert(is_in(result), "result should be in the heap"); - - // We will not do any dirtying here. This is guaranteed to be - // called during a safepoint and the thread that scheduled the - // pause will do the dirtying if we return a non-NULL result. - return result; - } - - retire_cur_alloc_region_common(cur_alloc_region); - } - } - - assert(_cur_alloc_region == NULL, - "at this point we should have no cur alloc region"); - return replace_cur_alloc_region_and_allocate(word_size, - true, /* at_safepoint */ - false /* do_dirtying */, - false /* can_expand */); - } else { - return attempt_allocation_humongous(word_size, - true /* at_safepoint */); - } - - ShouldNotReachHere(); -} - HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { assert_heap_not_locked_and_not_at_safepoint(); - assert(!isHumongous(word_size), "we do not allow TLABs of humongous size"); - - // First attempt: Try allocating out of the current alloc region - // using a CAS. If that fails, take the Heap_lock and retry the - // allocation, potentially replacing the current alloc region. - HeapWord* result = attempt_allocation(word_size); - if (result != NULL) { - assert_heap_not_locked(); - return result; - } - - // Second attempt: Go to the slower path where we might try to - // schedule a collection. - result = attempt_allocation_slow(word_size); - if (result != NULL) { - assert_heap_not_locked(); - return result; - } - - assert_heap_locked(); - // Need to unlock the Heap_lock before returning. - Heap_lock->unlock(); - return NULL; + assert(!isHumongous(word_size), "we do not allow humongous TLABs"); + + unsigned int dummy_gc_count_before; + return attempt_allocation(word_size, &dummy_gc_count_before); } HeapWord* @@ -1200,48 +805,18 @@ assert(!is_tlab, "mem_allocate() this should not be called directly " "to allocate TLABs"); - // Loop until the allocation is satisified, - // or unsatisfied after GC. + // Loop until the allocation is satisified, or unsatisfied after GC. for (int try_count = 1; /* we'll return */; try_count += 1) { unsigned int gc_count_before; - { - if (!isHumongous(word_size)) { - // First attempt: Try allocating out of the current alloc region - // using a CAS. If that fails, take the Heap_lock and retry the - // allocation, potentially replacing the current alloc region. - HeapWord* result = attempt_allocation(word_size); - if (result != NULL) { - assert_heap_not_locked(); - return result; - } - - assert_heap_locked(); - - // Second attempt: Go to the slower path where we might try to - // schedule a collection. - result = attempt_allocation_slow(word_size); - if (result != NULL) { - assert_heap_not_locked(); - return result; - } - } else { - // attempt_allocation_humongous() requires the Heap_lock to be held. - Heap_lock->lock(); - - HeapWord* result = attempt_allocation_humongous(word_size, - false /* at_safepoint */); - if (result != NULL) { - assert_heap_not_locked(); - return result; - } - } - - assert_heap_locked(); - // Read the gc count while the heap lock is held. - gc_count_before = SharedHeap::heap()->total_collections(); - - // Release the Heap_lock before attempting the collection. - Heap_lock->unlock(); + + HeapWord* result = NULL; + if (!isHumongous(word_size)) { + result = attempt_allocation(word_size, &gc_count_before); + } else { + result = attempt_allocation_humongous(word_size, &gc_count_before); + } + if (result != NULL) { + return result; } // Create the garbage collection operation... @@ -1249,7 +824,6 @@ // ...and get the VM thread to execute it. VMThread::execute(&op); - assert_heap_not_locked(); if (op.prologue_succeeded() && op.pause_succeeded()) { // If the operation was successful we'll return the result even // if it is NULL. If the allocation attempt failed immediately @@ -1275,21 +849,207 @@ } ShouldNotReachHere(); + return NULL; } -void G1CollectedHeap::abandon_cur_alloc_region() { +HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, + unsigned int *gc_count_before_ret) { + // Make sure you read the note in attempt_allocation_humongous(). + + assert_heap_not_locked_and_not_at_safepoint(); + assert(!isHumongous(word_size), "attempt_allocation_slow() should not " + "be called for humongous allocation requests"); + + // We should only get here after the first-level allocation attempt + // (attempt_allocation()) failed to allocate. + + // We will loop until a) we manage to successfully perform the + // allocation or b) we successfully schedule a collection which + // fails to perform the allocation. b) is the only case when we'll + // return NULL. + HeapWord* result = NULL; + for (int try_count = 1; /* we'll return */; try_count += 1) { + bool should_try_gc; + unsigned int gc_count_before; + + { + MutexLockerEx x(Heap_lock); + + result = _mutator_alloc_region.attempt_allocation_locked(word_size, + false /* bot_updates */); + if (result != NULL) { + return result; + } + + // If we reach here, attempt_allocation_locked() above failed to + // allocate a new region. So the mutator alloc region should be NULL. + assert(_mutator_alloc_region.get() == NULL, "only way to get here"); + + if (GC_locker::is_active_and_needs_gc()) { + if (g1_policy()->can_expand_young_list()) { + result = _mutator_alloc_region.attempt_allocation_force(word_size, + false /* bot_updates */); + if (result != NULL) { + return result; + } + } + should_try_gc = false; + } else { + // Read the GC count while still holding the Heap_lock. + gc_count_before = SharedHeap::heap()->total_collections(); + should_try_gc = true; + } + } + + if (should_try_gc) { + bool succeeded; + result = do_collection_pause(word_size, gc_count_before, &succeeded); + if (result != NULL) { + assert(succeeded, "only way to get back a non-NULL result"); + return result; + } + + if (succeeded) { + // If we get here we successfully scheduled a collection which + // failed to allocate. No point in trying to allocate + // further. We'll just return NULL. + MutexLockerEx x(Heap_lock); + *gc_count_before_ret = SharedHeap::heap()->total_collections(); + return NULL; + } + } else { + GC_locker::stall_until_clear(); + } + + // We can reach here if we were unsuccessul in scheduling a + // collection (because another thread beat us to it) or if we were + // stalled due to the GC locker. In either can we should retry the + // allocation attempt in case another thread successfully + // performed a collection and reclaimed enough space. We do the + // first attempt (without holding the Heap_lock) here and the + // follow-on attempt will be at the start of the next loop + // iteration (after taking the Heap_lock). + result = _mutator_alloc_region.attempt_allocation(word_size, + false /* bot_updates */); + if (result != NULL ){ + return result; + } + + // Give a warning if we seem to be looping forever. + if ((QueuedAllocationWarningCount > 0) && + (try_count % QueuedAllocationWarningCount == 0)) { + warning("G1CollectedHeap::attempt_allocation_slow() " + "retries %d times", try_count); + } + } + + ShouldNotReachHere(); + return NULL; +} + +HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, + unsigned int * gc_count_before_ret) { + // The structure of this method has a lot of similarities to + // attempt_allocation_slow(). The reason these two were not merged + // into a single one is that such a method would require several "if + // allocation is not humongous do this, otherwise do that" + // conditional paths which would obscure its flow. In fact, an early + // version of this code did use a unified method which was harder to + // follow and, as a result, it had subtle bugs that were hard to + // track down. So keeping these two methods separate allows each to + // be more readable. It will be good to keep these two in sync as + // much as possible. + + assert_heap_not_locked_and_not_at_safepoint(); + assert(isHumongous(word_size), "attempt_allocation_humongous() " + "should only be called for humongous allocations"); + + // We will loop until a) we manage to successfully perform the + // allocation or b) we successfully schedule a collection which + // fails to perform the allocation. b) is the only case when we'll + // return NULL. + HeapWord* result = NULL; + for (int try_count = 1; /* we'll return */; try_count += 1) { + bool should_try_gc; + unsigned int gc_count_before; + + { + MutexLockerEx x(Heap_lock); + + // Given that humongous objects are not allocated in young + // regions, we'll first try to do the allocation without doing a + // collection hoping that there's enough space in the heap. + result = humongous_obj_allocate(word_size); + if (result != NULL) { + return result; + } + + if (GC_locker::is_active_and_needs_gc()) { + should_try_gc = false; + } else { + // Read the GC count while still holding the Heap_lock. + gc_count_before = SharedHeap::heap()->total_collections(); + should_try_gc = true; + } + } + + if (should_try_gc) { + // If we failed to allocate the humongous object, we should try to + // do a collection pause (if we're allowed) in case it reclaims + // enough space for the allocation to succeed after the pause. + + bool succeeded; + result = do_collection_pause(word_size, gc_count_before, &succeeded); + if (result != NULL) { + assert(succeeded, "only way to get back a non-NULL result"); + return result; + } + + if (succeeded) { + // If we get here we successfully scheduled a collection which + // failed to allocate. No point in trying to allocate + // further. We'll just return NULL. + MutexLockerEx x(Heap_lock); + *gc_count_before_ret = SharedHeap::heap()->total_collections(); + return NULL; + } + } else { + GC_locker::stall_until_clear(); + } + + // We can reach here if we were unsuccessul in scheduling a + // collection (because another thread beat us to it) or if we were + // stalled due to the GC locker. In either can we should retry the + // allocation attempt in case another thread successfully + // performed a collection and reclaimed enough space. Give a + // warning if we seem to be looping forever. + + if ((QueuedAllocationWarningCount > 0) && + (try_count % QueuedAllocationWarningCount == 0)) { + warning("G1CollectedHeap::attempt_allocation_humongous() " + "retries %d times", try_count); + } + } + + ShouldNotReachHere(); + return NULL; +} + +HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, + bool expect_null_mutator_alloc_region) { assert_at_safepoint(true /* should_be_vm_thread */); - - HeapRegion* cur_alloc_region = _cur_alloc_region; - if (cur_alloc_region != NULL) { - assert(!cur_alloc_region->is_empty(), - "the current alloc region can never be empty"); - assert(cur_alloc_region->is_young(), - "the current alloc region should be young"); - - retire_cur_alloc_region_common(cur_alloc_region); - } - assert(_cur_alloc_region == NULL, "post-condition"); + assert(_mutator_alloc_region.get() == NULL || + !expect_null_mutator_alloc_region, + "the current alloc region was unexpectedly found to be non-NULL"); + + if (!isHumongous(word_size)) { + return _mutator_alloc_region.attempt_allocation_locked(word_size, + false /* bot_updates */); + } else { + return humongous_obj_allocate(word_size); + } + + ShouldNotReachHere(); } void G1CollectedHeap::abandon_gc_alloc_regions() { @@ -1417,8 +1177,8 @@ if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) { HandleMark hm; // Discard invalid handles created during verification + gclog_or_tty->print(" VerifyBeforeGC:"); prepare_for_verify(); - gclog_or_tty->print(" VerifyBeforeGC:"); Universe::verify(true); } @@ -1439,9 +1199,8 @@ concurrent_mark()->abort(); // Make sure we'll choose a new allocation region afterwards. - abandon_cur_alloc_region(); + release_mutator_alloc_region(); abandon_gc_alloc_regions(); - assert(_cur_alloc_region == NULL, "Invariant."); g1_rem_set()->cleanupHRRS(); tear_down_region_lists(); @@ -1547,6 +1306,8 @@ // evacuation pause. clear_cset_fast_test(); + init_mutator_alloc_region(); + double end = os::elapsedTime(); g1_policy()->record_full_collection_end(); @@ -1720,8 +1481,9 @@ *succeeded = true; // Let's attempt the allocation first. - HeapWord* result = attempt_allocation_at_safepoint(word_size, - false /* expect_null_cur_alloc_region */); + HeapWord* result = + attempt_allocation_at_safepoint(word_size, + false /* expect_null_mutator_alloc_region */); if (result != NULL) { assert(*succeeded, "sanity"); return result; @@ -1748,7 +1510,7 @@ // Retry the allocation result = attempt_allocation_at_safepoint(word_size, - true /* expect_null_cur_alloc_region */); + true /* expect_null_mutator_alloc_region */); if (result != NULL) { assert(*succeeded, "sanity"); return result; @@ -1765,7 +1527,7 @@ // Retry the allocation once more result = attempt_allocation_at_safepoint(word_size, - true /* expect_null_cur_alloc_region */); + true /* expect_null_mutator_alloc_region */); if (result != NULL) { assert(*succeeded, "sanity"); return result; @@ -1796,7 +1558,7 @@ if (expand(expand_bytes)) { verify_region_sets_optional(); return attempt_allocation_at_safepoint(word_size, - false /* expect_null_cur_alloc_region */); + false /* expect_null_mutator_alloc_region */); } return NULL; } @@ -1940,7 +1702,6 @@ _evac_failure_scan_stack(NULL) , _mark_in_progress(false), _cg1r(NULL), _summary_bytes_used(0), - _cur_alloc_region(NULL), _refine_cte_cl(NULL), _full_collection(false), _free_list("Master Free List"), @@ -2099,7 +1860,6 @@ _g1_max_committed = _g1_committed; _hrs = new HeapRegionSeq(_expansion_regions); guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq"); - guarantee(_cur_alloc_region == NULL, "from constructor"); // 6843694 - ensure that the maximum region index can fit // in the remembered set structures. @@ -2195,6 +1955,22 @@ // Do later initialization work for concurrent refinement. _cg1r->init(); + // Here we allocate the dummy full region that is required by the + // G1AllocRegion class. If we don't pass an address in the reserved + // space here, lots of asserts fire. + MemRegion mr(_g1_reserved.start(), HeapRegion::GrainWords); + HeapRegion* dummy_region = new HeapRegion(_bot_shared, mr, true); + // We'll re-use the same region whether the alloc region will + // require BOT updates or not and, if it doesn't, then a non-young + // region will complain that it cannot support allocations without + // BOT updates. So we'll tag the dummy region as young to avoid that. + dummy_region->set_young(); + // Make sure it's full. + dummy_region->set_top(dummy_region->end()); + G1AllocRegion::setup(this, dummy_region); + + init_mutator_alloc_region(); + return JNI_OK; } @@ -2261,7 +2037,7 @@ "Should be owned on this thread's behalf."); size_t result = _summary_bytes_used; // Read only once in case it is set to NULL concurrently - HeapRegion* hr = _cur_alloc_region; + HeapRegion* hr = _mutator_alloc_region.get(); if (hr != NULL) result += hr->used(); return result; @@ -2324,13 +2100,11 @@ // to free(), resulting in a SIGSEGV. Note that this doesn't appear // to be a problem in the optimized build, since the two loads of the // current allocation region field are optimized away. - HeapRegion* car = _cur_alloc_region; - - // FIXME: should iterate over all regions? - if (car == NULL) { + HeapRegion* hr = _mutator_alloc_region.get(); + if (hr == NULL) { return 0; } - return car->free(); + return hr->free(); } bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { @@ -2781,16 +2555,12 @@ // since we can't allow tlabs to grow big enough to accomodate // humongous objects. - // We need to store the cur alloc region locally, since it might change - // between when we test for NULL and when we use it later. - ContiguousSpace* cur_alloc_space = _cur_alloc_region; + HeapRegion* hr = _mutator_alloc_region.get(); size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize; - - if (cur_alloc_space == NULL) { + if (hr == NULL) { return max_tlab_size; } else { - return MIN2(MAX2(cur_alloc_space->free(), (size_t)MinTLABSize), - max_tlab_size); + return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size); } } @@ -3364,6 +3134,7 @@ } verify_region_sets_optional(); + verify_dirty_young_regions(); { // This call will decide whether this pause is an initial-mark @@ -3425,8 +3196,8 @@ if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) { HandleMark hm; // Discard invalid handles created during verification + gclog_or_tty->print(" VerifyBeforeGC:"); prepare_for_verify(); - gclog_or_tty->print(" VerifyBeforeGC:"); Universe::verify(false); } @@ -3442,7 +3213,7 @@ // Forget the current alloc region (we might even choose it to be part // of the collection set!). - abandon_cur_alloc_region(); + release_mutator_alloc_region(); // The elapsed time induced by the start time below deliberately elides // the possible verification above. @@ -3573,6 +3344,8 @@ g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); #endif // YOUNG_LIST_VERBOSE + init_mutator_alloc_region(); + double end_time_sec = os::elapsedTime(); double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS; g1_policy()->record_pause_time_ms(pause_time_ms); @@ -3655,6 +3428,15 @@ return gclab_word_size; } +void G1CollectedHeap::init_mutator_alloc_region() { + assert(_mutator_alloc_region.get() == NULL, "pre-condition"); + _mutator_alloc_region.init(); +} + +void G1CollectedHeap::release_mutator_alloc_region() { + _mutator_alloc_region.release(); + assert(_mutator_alloc_region.get() == NULL, "post-condition"); +} void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) { assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose"); @@ -5140,10 +4922,8 @@ CardTableModRefBS* _ct_bs; public: G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs) - : _ct_bs(ct_bs) - { } - virtual bool doHeapRegion(HeapRegion* r) - { + : _ct_bs(ct_bs) { } + virtual bool doHeapRegion(HeapRegion* r) { MemRegion mr(r->bottom(), r->end()); if (r->is_survivor()) { _ct_bs->verify_dirty_region(mr); @@ -5153,6 +4933,29 @@ return false; } }; + +void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { + CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set()); + for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { + // We cannot guarantee that [bottom(),end()] is dirty. Threads + // dirty allocated blocks as they allocate them. The thread that + // retires each region and replaces it with a new one will do a + // maximal allocation to fill in [pre_dummy_top(),end()] but will + // not dirty that area (one less thing to have to do while holding + // a lock). So we can only verify that [bottom(),pre_dummy_top()] + // is dirty. Also note that verify_dirty_region() requires + // mr.start() and mr.end() to be card aligned and pre_dummy_top() + // is not guaranteed to be. + MemRegion mr(hr->bottom(), + ct_bs->align_to_card_boundary(hr->pre_dummy_top())); + ct_bs->verify_dirty_region(mr); + } +} + +void G1CollectedHeap::verify_dirty_young_regions() { + verify_dirty_young_list(_young_list->first_region()); + verify_dirty_young_list(_young_list->first_survivor_region()); +} #endif void G1CollectedHeap::cleanUpCardTable() { @@ -5500,6 +5303,44 @@ } } +HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, + bool force) { + assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); + assert(!force || g1_policy()->can_expand_young_list(), + "if force is true we should be able to expand the young list"); + if (force || !g1_policy()->is_young_list_full()) { + HeapRegion* new_alloc_region = new_region(word_size, + false /* do_expand */); + if (new_alloc_region != NULL) { + g1_policy()->update_region_num(true /* next_is_young */); + set_region_short_lived_locked(new_alloc_region); + return new_alloc_region; + } + } + return NULL; +} + +void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, + size_t allocated_bytes) { + assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); + assert(alloc_region->is_young(), "all mutator alloc regions should be young"); + + g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); + _summary_bytes_used += allocated_bytes; +} + +HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, + bool force) { + return _g1h->new_mutator_alloc_region(word_size, force); +} + +void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, + size_t allocated_bytes) { + _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); +} + +// Heap region set verification + class VerifyRegionListsClosure : public HeapRegionClosure { private: HumongousRegionSet* _humongous_set;