Thu, 21 Aug 2014 16:44:41 +0200
8055098: WB API should be extended to provide information about size and age of object.
Summary: Extend the WhiteBox API to provide information about the size and age of objects. Further add a mechanism to trigger a young GC.
Reviewed-by: tschatzl, sjohanss
Contributed-by: Leonid Mesnik <leonid.mesnik@oracle.com>
ysr@777 | 1 | /* |
sla@5237 | 2 | * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved. |
ysr@777 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
ysr@777 | 4 | * |
ysr@777 | 5 | * This code is free software; you can redistribute it and/or modify it |
ysr@777 | 6 | * under the terms of the GNU General Public License version 2 only, as |
ysr@777 | 7 | * published by the Free Software Foundation. |
ysr@777 | 8 | * |
ysr@777 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
ysr@777 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
ysr@777 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
ysr@777 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
ysr@777 | 13 | * accompanied this code). |
ysr@777 | 14 | * |
ysr@777 | 15 | * You should have received a copy of the GNU General Public License version |
ysr@777 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
ysr@777 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
ysr@777 | 18 | * |
trims@1907 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
trims@1907 | 20 | * or visit www.oracle.com if you need additional information or have any |
trims@1907 | 21 | * questions. |
ysr@777 | 22 | * |
ysr@777 | 23 | */ |
ysr@777 | 24 | |
stefank@2314 | 25 | #include "precompiled.hpp" |
johnc@3218 | 26 | #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" |
stefank@2314 | 27 | #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" |
stefank@2314 | 28 | #include "gc_implementation/g1/g1CollectorPolicy.hpp" |
brutisso@3710 | 29 | #include "gc_implementation/g1/g1Log.hpp" |
stefank@2314 | 30 | #include "gc_implementation/g1/vm_operations_g1.hpp" |
sla@5237 | 31 | #include "gc_implementation/shared/gcTimer.hpp" |
sla@5237 | 32 | #include "gc_implementation/shared/gcTraceTime.hpp" |
stefank@2314 | 33 | #include "gc_implementation/shared/isGCActiveMark.hpp" |
tonyp@2315 | 34 | #include "gc_implementation/g1/vm_operations_g1.hpp" |
stefank@2314 | 35 | #include "runtime/interfaceSupport.hpp" |
ysr@777 | 36 | |
tonyp@2315 | 37 | VM_G1CollectForAllocation::VM_G1CollectForAllocation( |
tonyp@2315 | 38 | unsigned int gc_count_before, |
tonyp@2315 | 39 | size_t word_size) |
johnc@3666 | 40 | : VM_G1OperationWithAllocRequest(gc_count_before, word_size, |
johnc@3666 | 41 | GCCause::_allocation_failure) { |
tonyp@2315 | 42 | guarantee(word_size > 0, "an allocation should always be requested"); |
tonyp@2315 | 43 | } |
tonyp@2315 | 44 | |
ysr@777 | 45 | void VM_G1CollectForAllocation::doit() { |
ysr@777 | 46 | G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
johnc@3765 | 47 | GCCauseSetter x(g1h, _gc_cause); |
tonyp@2315 | 48 | _result = g1h->satisfy_failed_allocation(_word_size, &_pause_succeeded); |
tonyp@2315 | 49 | assert(_result == NULL || _pause_succeeded, |
tonyp@2315 | 50 | "if we get back a result, the pause should have succeeded"); |
ysr@777 | 51 | } |
ysr@777 | 52 | |
ysr@777 | 53 | void VM_G1CollectFull::doit() { |
ysr@777 | 54 | G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
ysr@777 | 55 | GCCauseSetter x(g1h, _gc_cause); |
ysr@777 | 56 | g1h->do_full_collection(false /* clear_all_soft_refs */); |
ysr@777 | 57 | } |
ysr@777 | 58 | |
tonyp@2315 | 59 | VM_G1IncCollectionPause::VM_G1IncCollectionPause( |
tonyp@2315 | 60 | unsigned int gc_count_before, |
tonyp@2315 | 61 | size_t word_size, |
tonyp@2315 | 62 | bool should_initiate_conc_mark, |
tonyp@2315 | 63 | double target_pause_time_ms, |
tonyp@2315 | 64 | GCCause::Cause gc_cause) |
johnc@3666 | 65 | : VM_G1OperationWithAllocRequest(gc_count_before, word_size, gc_cause), |
tonyp@2315 | 66 | _should_initiate_conc_mark(should_initiate_conc_mark), |
tonyp@2315 | 67 | _target_pause_time_ms(target_pause_time_ms), |
johnc@3666 | 68 | _should_retry_gc(false), |
brutisso@3823 | 69 | _old_marking_cycles_completed_before(0) { |
tonyp@2315 | 70 | guarantee(target_pause_time_ms > 0.0, |
tonyp@2315 | 71 | err_msg("target_pause_time_ms = %1.6lf should be positive", |
tonyp@2315 | 72 | target_pause_time_ms)); |
tonyp@2315 | 73 | _gc_cause = gc_cause; |
tonyp@2315 | 74 | } |
tonyp@2315 | 75 | |
johnc@3666 | 76 | bool VM_G1IncCollectionPause::doit_prologue() { |
johnc@3666 | 77 | bool res = VM_GC_Operation::doit_prologue(); |
johnc@3666 | 78 | if (!res) { |
johnc@3666 | 79 | if (_should_initiate_conc_mark) { |
johnc@3666 | 80 | // The prologue can fail for a couple of reasons. The first is that another GC |
johnc@3666 | 81 | // got scheduled and prevented the scheduling of the initial mark GC. The |
johnc@3666 | 82 | // second is that the GC locker may be active and the heap can't be expanded. |
johnc@3666 | 83 | // In both cases we want to retry the GC so that the initial mark pause is |
johnc@3666 | 84 | // actually scheduled. In the second case, however, we should stall until |
johnc@3666 | 85 | // until the GC locker is no longer active and then retry the initial mark GC. |
johnc@3666 | 86 | _should_retry_gc = true; |
johnc@3666 | 87 | } |
johnc@3666 | 88 | } |
johnc@3666 | 89 | return res; |
johnc@3666 | 90 | } |
johnc@3666 | 91 | |
ysr@777 | 92 | void VM_G1IncCollectionPause::doit() { |
ysr@777 | 93 | G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
tonyp@2011 | 94 | assert(!_should_initiate_conc_mark || |
tonyp@2011 | 95 | ((_gc_cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) || |
brutisso@3456 | 96 | (_gc_cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent) || |
brutisso@3456 | 97 | _gc_cause == GCCause::_g1_humongous_allocation), |
brutisso@3456 | 98 | "only a GC locker, a System.gc() or a hum allocation induced GC should start a cycle"); |
tonyp@2011 | 99 | |
tonyp@2315 | 100 | if (_word_size > 0) { |
tonyp@2315 | 101 | // An allocation has been requested. So, try to do that first. |
tonyp@2315 | 102 | _result = g1h->attempt_allocation_at_safepoint(_word_size, |
tonyp@2315 | 103 | false /* expect_null_cur_alloc_region */); |
tonyp@2315 | 104 | if (_result != NULL) { |
tonyp@2315 | 105 | // If we can successfully allocate before we actually do the |
tonyp@2315 | 106 | // pause then we will consider this pause successful. |
tonyp@2315 | 107 | _pause_succeeded = true; |
tonyp@2315 | 108 | return; |
tonyp@2315 | 109 | } |
tonyp@2315 | 110 | } |
tonyp@2315 | 111 | |
ysr@1523 | 112 | GCCauseSetter x(g1h, _gc_cause); |
tonyp@2011 | 113 | if (_should_initiate_conc_mark) { |
brutisso@3823 | 114 | // It's safer to read old_marking_cycles_completed() here, given |
tonyp@2011 | 115 | // that noone else will be updating it concurrently. Since we'll |
tonyp@2011 | 116 | // only need it if we're initiating a marking cycle, no point in |
tonyp@2011 | 117 | // setting it earlier. |
brutisso@3823 | 118 | _old_marking_cycles_completed_before = g1h->old_marking_cycles_completed(); |
tonyp@2011 | 119 | |
tonyp@2011 | 120 | // At this point we are supposed to start a concurrent cycle. We |
tonyp@2011 | 121 | // will do so if one is not already in progress. |
tonyp@3114 | 122 | bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause); |
johnc@2970 | 123 | |
johnc@2970 | 124 | // The above routine returns true if we were able to force the |
johnc@2970 | 125 | // next GC pause to be an initial mark; it returns false if a |
johnc@2970 | 126 | // marking cycle is already in progress. |
johnc@2970 | 127 | // |
johnc@3666 | 128 | // If a marking cycle is already in progress just return and skip the |
johnc@3666 | 129 | // pause below - if the reason for requesting this initial mark pause |
johnc@3666 | 130 | // was due to a System.gc() then the requesting thread should block in |
johnc@3666 | 131 | // doit_epilogue() until the marking cycle is complete. |
johnc@3666 | 132 | // |
johnc@3666 | 133 | // If this initial mark pause was requested as part of a humongous |
johnc@3666 | 134 | // allocation then we know that the marking cycle must just have |
johnc@3666 | 135 | // been started by another thread (possibly also allocating a humongous |
johnc@3666 | 136 | // object) as there was no active marking cycle when the requesting |
johnc@3666 | 137 | // thread checked before calling collect() in |
johnc@3666 | 138 | // attempt_allocation_humongous(). Retrying the GC, in this case, |
johnc@3666 | 139 | // will cause the requesting thread to spin inside collect() until the |
johnc@3666 | 140 | // just started marking cycle is complete - which may be a while. So |
johnc@3666 | 141 | // we do NOT retry the GC. |
johnc@2970 | 142 | if (!res) { |
johnc@3666 | 143 | assert(_word_size == 0, "Concurrent Full GC/Humongous Object IM shouldn't be allocating"); |
johnc@3666 | 144 | if (_gc_cause != GCCause::_g1_humongous_allocation) { |
johnc@3666 | 145 | _should_retry_gc = true; |
johnc@3666 | 146 | } |
johnc@2970 | 147 | return; |
johnc@2970 | 148 | } |
tonyp@2011 | 149 | } |
tonyp@2315 | 150 | |
tonyp@2315 | 151 | _pause_succeeded = |
tonyp@2315 | 152 | g1h->do_collection_pause_at_safepoint(_target_pause_time_ms); |
tonyp@2315 | 153 | if (_pause_succeeded && _word_size > 0) { |
tonyp@2315 | 154 | // An allocation had been requested. |
tonyp@2315 | 155 | _result = g1h->attempt_allocation_at_safepoint(_word_size, |
tonyp@2315 | 156 | true /* expect_null_cur_alloc_region */); |
tonyp@2315 | 157 | } else { |
tonyp@2315 | 158 | assert(_result == NULL, "invariant"); |
johnc@3666 | 159 | if (!_pause_succeeded) { |
johnc@3666 | 160 | // Another possible reason reason for the pause to not be successful |
johnc@3666 | 161 | // is that, again, the GC locker is active (and has become active |
johnc@3666 | 162 | // since the prologue was executed). In this case we should retry |
johnc@3666 | 163 | // the pause after waiting for the GC locker to become inactive. |
johnc@3666 | 164 | _should_retry_gc = true; |
johnc@3666 | 165 | } |
tonyp@2315 | 166 | } |
tonyp@2011 | 167 | } |
tonyp@2011 | 168 | |
tonyp@2011 | 169 | void VM_G1IncCollectionPause::doit_epilogue() { |
tonyp@2011 | 170 | VM_GC_Operation::doit_epilogue(); |
tonyp@2011 | 171 | |
tonyp@2011 | 172 | // If the pause was initiated by a System.gc() and |
tonyp@2011 | 173 | // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle |
tonyp@2011 | 174 | // that just started (or maybe one that was already in progress) to |
tonyp@2011 | 175 | // finish. |
tonyp@2011 | 176 | if (_gc_cause == GCCause::_java_lang_system_gc && |
tonyp@2011 | 177 | _should_initiate_conc_mark) { |
tonyp@2011 | 178 | assert(ExplicitGCInvokesConcurrent, |
tonyp@2011 | 179 | "the only way to be here is if ExplicitGCInvokesConcurrent is set"); |
tonyp@2011 | 180 | |
tonyp@2011 | 181 | G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
tonyp@2011 | 182 | |
brutisso@3823 | 183 | // In the doit() method we saved g1h->old_marking_cycles_completed() |
brutisso@3823 | 184 | // in the _old_marking_cycles_completed_before field. We have to |
brutisso@3823 | 185 | // wait until we observe that g1h->old_marking_cycles_completed() |
tonyp@2011 | 186 | // has increased by at least one. This can happen if a) we started |
tonyp@2011 | 187 | // a cycle and it completes, b) a cycle already in progress |
tonyp@2011 | 188 | // completes, or c) a Full GC happens. |
tonyp@2011 | 189 | |
tonyp@2011 | 190 | // If the condition has already been reached, there's no point in |
tonyp@2011 | 191 | // actually taking the lock and doing the wait. |
brutisso@3823 | 192 | if (g1h->old_marking_cycles_completed() <= |
brutisso@3823 | 193 | _old_marking_cycles_completed_before) { |
tonyp@2011 | 194 | // The following is largely copied from CMS |
tonyp@2011 | 195 | |
tonyp@2011 | 196 | Thread* thr = Thread::current(); |
tonyp@2011 | 197 | assert(thr->is_Java_thread(), "invariant"); |
tonyp@2011 | 198 | JavaThread* jt = (JavaThread*)thr; |
tonyp@2011 | 199 | ThreadToNativeFromVM native(jt); |
tonyp@2011 | 200 | |
tonyp@2011 | 201 | MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); |
brutisso@3823 | 202 | while (g1h->old_marking_cycles_completed() <= |
brutisso@3823 | 203 | _old_marking_cycles_completed_before) { |
tonyp@2011 | 204 | FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag); |
tonyp@2011 | 205 | } |
tonyp@2011 | 206 | } |
tonyp@2011 | 207 | } |
ysr@777 | 208 | } |
ysr@777 | 209 | |
johnc@3218 | 210 | void VM_CGC_Operation::acquire_pending_list_lock() { |
johnc@3666 | 211 | assert(_needs_pll, "don't call this otherwise"); |
johnc@3218 | 212 | // The caller may block while communicating |
johnc@3218 | 213 | // with the SLT thread in order to acquire/release the PLL. |
johnc@3218 | 214 | ConcurrentMarkThread::slt()-> |
johnc@3218 | 215 | manipulatePLL(SurrogateLockerThread::acquirePLL); |
johnc@3218 | 216 | } |
johnc@3218 | 217 | |
johnc@3218 | 218 | void VM_CGC_Operation::release_and_notify_pending_list_lock() { |
johnc@3666 | 219 | assert(_needs_pll, "don't call this otherwise"); |
johnc@3218 | 220 | // The caller may block while communicating |
johnc@3218 | 221 | // with the SLT thread in order to acquire/release the PLL. |
johnc@3218 | 222 | ConcurrentMarkThread::slt()-> |
johnc@3218 | 223 | manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL); |
johnc@3218 | 224 | } |
johnc@3218 | 225 | |
ysr@777 | 226 | void VM_CGC_Operation::doit() { |
brutisso@3710 | 227 | gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); |
brutisso@3710 | 228 | TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); |
brutisso@6904 | 229 | GCTraceTime t(_printGCMessage, G1Log::fine(), true, G1CollectedHeap::heap()->gc_timer_cm(), G1CollectedHeap::heap()->concurrent_mark()->concurrent_gc_id()); |
ysr@777 | 230 | SharedHeap* sh = SharedHeap::heap(); |
ysr@777 | 231 | // This could go away if CollectedHeap gave access to _gc_is_active... |
ysr@777 | 232 | if (sh != NULL) { |
ysr@777 | 233 | IsGCActiveMark x; |
ysr@777 | 234 | _cl->do_void(); |
ysr@777 | 235 | } else { |
ysr@777 | 236 | _cl->do_void(); |
ysr@777 | 237 | } |
ysr@777 | 238 | } |
ysr@777 | 239 | |
ysr@777 | 240 | bool VM_CGC_Operation::doit_prologue() { |
johnc@3218 | 241 | // Note the relative order of the locks must match that in |
johnc@3218 | 242 | // VM_GC_Operation::doit_prologue() or deadlocks can occur |
johnc@3666 | 243 | if (_needs_pll) { |
johnc@3666 | 244 | acquire_pending_list_lock(); |
johnc@3666 | 245 | } |
johnc@3218 | 246 | |
ysr@777 | 247 | Heap_lock->lock(); |
ysr@777 | 248 | SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true; |
ysr@777 | 249 | return true; |
ysr@777 | 250 | } |
ysr@777 | 251 | |
ysr@777 | 252 | void VM_CGC_Operation::doit_epilogue() { |
johnc@3218 | 253 | // Note the relative order of the unlocks must match that in |
johnc@3218 | 254 | // VM_GC_Operation::doit_epilogue() |
ysr@777 | 255 | SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false; |
ysr@777 | 256 | Heap_lock->unlock(); |
johnc@3666 | 257 | if (_needs_pll) { |
johnc@3666 | 258 | release_and_notify_pending_list_lock(); |
johnc@3666 | 259 | } |
ysr@777 | 260 | } |