From 1b842ee9ba73478a9fb98d1d03d26175088145b2 Mon Sep 17 00:00:00 2001 From: mgerdin Date: Thu, 28 Mar 2013 10:27:28 +0100 Subject: [PATCH] 7014552: gc/lock/jni/jnilockXXX works too slow on 1-processor machine Summary: Keep a counter of how many times we were stalled by the GC locker, add a diagnostic flag which sets the limit. Reviewed-by: brutisso, ehelin, johnc --- .../gc_implementation/g1/g1CollectedHeap.cpp | 30 +++++++++++++++---- .../gc_implementation/g1/g1CollectedHeap.hpp | 9 ++++-- .../g1/g1CollectedHeap.inline.hpp | 7 +++-- .../parallelScavenge/parallelScavengeHeap.cpp | 6 ++++ src/share/vm/memory/collectorPolicy.cpp | 7 ++++- src/share/vm/runtime/globals.hpp | 4 +++ 6 files changed, 51 insertions(+), 12 deletions(-) diff --git a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp index 646479790..780e330b4 100644 --- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp @@ -854,7 +854,8 @@ HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 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); + int dummy_gclocker_retry_count = 0; + return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); } HeapWord* @@ -863,14 +864,14 @@ G1CollectedHeap::mem_allocate(size_t word_size, assert_heap_not_locked_and_not_at_safepoint(); // Loop until the allocation is satisified, or unsatisfied after GC. - for (int try_count = 1; /* we'll return */; try_count += 1) { + for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { unsigned int gc_count_before; HeapWord* result = NULL; if (!isHumongous(word_size)) { - result = attempt_allocation(word_size, &gc_count_before); + result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); } else { - result = attempt_allocation_humongous(word_size, &gc_count_before); + result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); } if (result != NULL) { return result; @@ -894,6 +895,9 @@ G1CollectedHeap::mem_allocate(size_t word_size, } return result; } else { + if (gclocker_retry_count > GCLockerRetryAllocationCount) { + return NULL; + } assert(op.result() == NULL, "the result should be NULL if the VM op did not succeed"); } @@ -910,7 +914,8 @@ G1CollectedHeap::mem_allocate(size_t word_size, } HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, - unsigned int *gc_count_before_ret) { + unsigned int *gc_count_before_ret, + int* gclocker_retry_count_ret) { // Make sure you read the note in attempt_allocation_humongous(). assert_heap_not_locked_and_not_at_safepoint(); @@ -986,10 +991,16 @@ HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, return NULL; } } else { + if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { + MutexLockerEx x(Heap_lock); + *gc_count_before_ret = total_collections(); + return NULL; + } // The GCLocker is either active or the GCLocker initiated // GC has not yet been performed. Stall until it is and // then retry the allocation. GC_locker::stall_until_clear(); + (*gclocker_retry_count_ret) += 1; } // We can reach here if we were unsuccessul in scheduling a @@ -1019,7 +1030,8 @@ HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, } HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, - unsigned int * gc_count_before_ret) { + unsigned int * gc_count_before_ret, + int* gclocker_retry_count_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 @@ -1104,10 +1116,16 @@ HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, return NULL; } } else { + if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { + MutexLockerEx x(Heap_lock); + *gc_count_before_ret = total_collections(); + return NULL; + } // The GCLocker is either active or the GCLocker initiated // GC has not yet been performed. Stall until it is and // then retry the allocation. GC_locker::stall_until_clear(); + (*gclocker_retry_count_ret) += 1; } // We can reach here if we were unsuccessul in scheduling a diff --git a/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp b/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp index 7dc5bd830..557daf85e 100644 --- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp @@ -559,18 +559,21 @@ protected: // the mutator alloc region without taking the Heap_lock. This // should only be used for non-humongous allocations. inline HeapWord* attempt_allocation(size_t word_size, - unsigned int* gc_count_before_ret); + unsigned int* gc_count_before_ret, + int* gclocker_retry_count_ret); // Second-level mutator allocation attempt: take the Heap_lock and // retry the allocation attempt, potentially scheduling a GC // pause. This should only be used for non-humongous allocations. HeapWord* attempt_allocation_slow(size_t word_size, - unsigned int* gc_count_before_ret); + unsigned int* gc_count_before_ret, + int* gclocker_retry_count_ret); // Takes the Heap_lock and attempts a humongous allocation. It can // potentially schedule a GC pause. HeapWord* attempt_allocation_humongous(size_t word_size, - unsigned int* gc_count_before_ret); + unsigned int* gc_count_before_ret, + int* gclocker_retry_count_ret); // Allocation attempt that should be called during safepoints (e.g., // at the end of a successful GC). expect_null_mutator_alloc_region diff --git a/src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp b/src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp index 4f9c77262..20eb1693c 100644 --- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp @@ -60,7 +60,8 @@ inline bool G1CollectedHeap::obj_in_cs(oop obj) { inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, - unsigned int* gc_count_before_ret) { + unsigned int* gc_count_before_ret, + int* gclocker_retry_count_ret) { assert_heap_not_locked_and_not_at_safepoint(); assert(!isHumongous(word_size), "attempt_allocation() should not " "be called for humongous allocation requests"); @@ -68,7 +69,9 @@ G1CollectedHeap::attempt_allocation(size_t word_size, HeapWord* result = _mutator_alloc_region.attempt_allocation(word_size, false /* bot_updates */); if (result == NULL) { - result = attempt_allocation_slow(word_size, gc_count_before_ret); + result = attempt_allocation_slow(word_size, + gc_count_before_ret, + gclocker_retry_count_ret); } assert_heap_not_locked(); if (result != NULL) { diff --git a/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp b/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp index 0c39e69e1..5d77e31b6 100644 --- a/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp +++ b/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp @@ -326,6 +326,7 @@ HeapWord* ParallelScavengeHeap::mem_allocate( uint loop_count = 0; uint gc_count = 0; + int gclocker_stalled_count = 0; while (result == NULL) { // We don't want to have multiple collections for a single filled generation. @@ -354,6 +355,10 @@ HeapWord* ParallelScavengeHeap::mem_allocate( return result; } + if (gclocker_stalled_count > GCLockerRetryAllocationCount) { + return NULL; + } + // Failed to allocate without a gc. if (GC_locker::is_active_and_needs_gc()) { // If this thread is not in a jni critical section, we stall @@ -366,6 +371,7 @@ HeapWord* ParallelScavengeHeap::mem_allocate( if (!jthr->in_critical()) { MutexUnlocker mul(Heap_lock); GC_locker::stall_until_clear(); + gclocker_stalled_count += 1; continue; } else { if (CheckJNICalls) { diff --git a/src/share/vm/memory/collectorPolicy.cpp b/src/share/vm/memory/collectorPolicy.cpp index d5eb387a0..a2049597a 100644 --- a/src/share/vm/memory/collectorPolicy.cpp +++ b/src/share/vm/memory/collectorPolicy.cpp @@ -532,7 +532,7 @@ HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size, // Loop until the allocation is satisified, // or unsatisfied after GC. - for (int try_count = 1; /* return or throw */; try_count += 1) { + for (int try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) { HandleMark hm; // discard any handles allocated in each iteration // First allocation attempt is lock-free. @@ -576,6 +576,10 @@ HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size, } } + if (gclocker_stalled_count > GCLockerRetryAllocationCount) { + return NULL; // we didn't get to do a GC and we didn't get any memory + } + // 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 @@ -587,6 +591,7 @@ HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size, MutexUnlocker mul(Heap_lock); // Wait for JNI critical section to be exited GC_locker::stall_until_clear(); + gclocker_stalled_count += 1; continue; } else { if (CheckJNICalls) { diff --git a/src/share/vm/runtime/globals.hpp b/src/share/vm/runtime/globals.hpp index 9645f625a..d59bc735e 100644 --- a/src/share/vm/runtime/globals.hpp +++ b/src/share/vm/runtime/globals.hpp @@ -1402,6 +1402,10 @@ class CommandLineFlags { "How much the GC can expand the eden by while the GC locker " \ "is active (as a percentage)") \ \ + diagnostic(intx, GCLockerRetryAllocationCount, 2, \ + "Number of times to retry allocations when" \ + " blocked by the GC locker") \ + \ develop(bool, UseCMSAdaptiveFreeLists, true, \ "Use Adaptive Free Lists in the CMS generation") \ \ -- GitLab