我有一个关于V8的小问题6.7.240
GC 行为和AddGCPrologueCallback
/AddGCEpilogueCallback
回调。
问题背后的一个小故事:我们使用 V8 引擎启动自定义 JS 代码,为了限制执行时间,我们有一个watchdog
(单独的线程与isolate->TerminateExecution()
call)监视代码并在长时间运行时杀死它,但与 GC 活动有关。
因此,如果代码执行超时等于200ms
, GC 活动需要300ms
代码需要199ms
我们会没事的(199ms
< 200ms
, 300ms
不包括在内)。
另一方面,如果代码执行超时等于200ms
, GC 活动需要300ms
代码需要201ms
这将是执行超时(201ms
> 200ms
, 300ms
不包括在内)。
正如您所看到的,精确的 GC 测量非常重要,因为如果 GC 活动花费的时间超过回调指示的时间,则可能会导致以下情况watchdog
会注意到代码运行时间太长并杀死它,但实际上 GC 活动(以及“停止世界”方法)“吃掉”时间,而没有任何迹象表明这一点。
看来这正是我们在测试和调试过程中注意到的。让我们来看看:
V8 side:
// init step
api,v8::Context::New
[api,v8::FunctionTemplate::New]
// a little bit fancy way of converting string to object
// like JSON:Parse call, but doing that using global JSON object
// no problem with that, just part of the log
api,v8::String::NewFromUtf8
api,v8::Object::Get
api,v8::String::NewFromUtf8
api,v8::Object::Get
api,v8::String::NewFromUtf8
timer-event-start,V8.GCIncrementalMarking,6406056058
timer-event-end,V8.GCIncrementalMarking,6406056581
api,v8::Function::Call
// actually function run
// script->Run(context);
timer-event-start,V8.Execute,6406057062
timer-event-start,V8.GCIncrementalMarking,6406057179
timer-event-end,V8.GCIncrementalMarking,6406059180
timer-event-start,V8.GCIncrementalMarking,6406060424
timer-event-end,V8.GCIncrementalMarking,6406062569
timer-event-start,V8.GCIncrementalMarking,6406063674
timer-event-end,V8.GCIncrementalMarking,6406065864
timer-event-start,V8.GCIncrementalMarking,6406066891
timer-event-end,V8.GCIncrementalMarking,6406068970
timer-event-start,V8.GCIncrementalMarking,6406069912
timer-event-end,V8.GCIncrementalMarking,6406070711
timer-event-start,V8.GCIncrementalMarking,6406071368
timer-event-end,V8.GCIncrementalMarking,6406073392
timer-event-start,V8.GCIncrementalMarking,6406074204
timer-event-end,V8.GCIncrementalMarking,6406076411
timer-event-start,V8.GCIncrementalMarking,6406077223
timer-event-end,V8.GCIncrementalMarking,6406079326
timer-event-start,V8.GCIncrementalMarking,6406080096
timer-event-end,V8.GCIncrementalMarking,6406082253
timer-event-start,V8.GCIncrementalMarking,6406083041
timer-event-end,V8.GCIncrementalMarking,6406085169
timer-event-start,V8.GCIncrementalMarking,6406085754
timer-event-end,V8.GCIncrementalMarking,6406087852
timer-event-start,V8.GCIncrementalMarking,6406088753
timer-event-end,V8.GCIncrementalMarking,6406090888
timer-event-start,V8.GCIncrementalMarking,6406091704
timer-event-end,V8.GCIncrementalMarking,6406093860
timer-event-start,V8.GCIncrementalMarking,6406094638
timer-event-end,V8.GCIncrementalMarking,6406096819
timer-event-start,V8.GCIncrementalMarking,6406097737
timer-event-end,V8.GCIncrementalMarking,6406099851
timer-event-start,V8.GCIncrementalMarking,6406100651
timer-event-end,V8.GCIncrementalMarking,6406102158
timer-event-start,V8.GCIncrementalMarking,6406102830
timer-event-end,V8.GCIncrementalMarking,6406102949
timer-event-start,V8.GCIncrementalMarkingFinalize,6406103476
timer-event-end,V8.GCIncrementalMarkingFinalize,6406103720
timer-event-start,V8.GCIncrementalMarking,6406103781
timer-event-end,V8.GCIncrementalMarking,6406103805
timer-event-start,V8.GCFinalizeMC,6406106106
markcompact,begin,37,733899,1573929817539
sfi-move,0x26c8c6b42258,0x39727ab446f0
sfi-move,0x26c8c6b423d0,0x39727ab44858
code-move,0x26c8c6b424a8,0x39727ab44920
code-move,0x26c8c6b42990,0x39727ab44e08
[delete,MemoryChunk,0x20803a500000]
markcompact,end,37,750515,1573929817560
timer-event-end,V8.GCFinalizeMC,6406126613
[delete,MemoryChunk,0x2fcf14300000]
timer-event-start,V8.GCIncrementalMarkingStart,
timer-event-end,V8.GCIncrementalMarkingStart,6406148920
timer-event-start,V8.GCIncrementalMarking,6406148975
timer-event-end,V8.GCIncrementalMarking,6406150059
timer-event-start,V8.GCIncrementalMarking,6406151014
timer-event-end,V8.GCIncrementalMarking,6406152657
timer-event-start,V8.GCIncrementalMarking,6406153356
timer-event-end,V8.GCIncrementalMarking,6406154995
timer-event-start,V8.GCIncrementalMarking,6406155703
timer-event-end,V8.GCIncrementalMarking,6406157341
new,MemoryChunk,0x24eee1900000,524288
timer-event-start,V8.GCIncrementalMarking,6406158486
timer-event-end,V8.GCIncrementalMarking,6406160149
new,MemoryChunk,0x7f310200000,524288
timer-event-start,V8.GCIncrementalMarking,6406161218
timer-event-end,V8.GCIncrementalMarking,6406162914
new,MemoryChunk,0x178aad500000,524288
timer-event-start,V8.GCIncrementalMarking,6406163990
timer-event-end,V8.GCIncrementalMarking,6406165681
new,MemoryChunk,0x34d7b2580000,524288
timer-event-start,V8.GCIncrementalMarking,6406166748
timer-event-end,V8.GCIncrementalMarking,6406168439
new,MemoryChunk,0x225fec080000,524288
timer-event-start,V8.GCIncrementalMarking,6406169481
timer-event-end,V8.GCIncrementalMarking,6406171229
new,MemoryChunk,0x502e7380000,524288
timer-event-start,V8.GCIncrementalMarking,6406172280
timer-event-end,V8.GCIncrementalMarking,6406174003
new,MemoryChunk,0x208b2af00000,524288
timer-event-start,V8.GCIncrementalMarking,6406175047
timer-event-end,V8.GCIncrementalMarking,6406176787
new,MemoryChunk,0x39ffd8400000,524288
timer-event-start,V8.GCIncrementalMarking,6406177851
timer-event-end,V8.GCIncrementalMarking,6406179600
new,MemoryChunk,0x10408d480000,524288
timer-event-start,V8.GCIncrementalMarking,6406180631
timer-event-end,V8.GCIncrementalMarking,6406182384
new,MemoryChunk,0x25c069e80000,524288
timer-event-start,V8.GCIncrementalMarking,6406183415
timer-event-end,V8.GCIncrementalMarking,6406185165
new,MemoryChunk,0x20cb51c80000,524288
timer-event-start,V8.GCIncrementalMarking,6406186210
timer-event-end,V8.GCIncrementalMarking,6406186919
new,MemoryChunk,0xe774a300000,524288
timer-event-start,V8.GCIncrementalMarking,6406187940
timer-event-end,V8.GCIncrementalMarking,6406188387
new,MemoryChunk,0x23a0a1180000,524288
timer-event-start,V8.GCIncrementalMarking,6406189172
timer-event-end,V8.GCIncrementalMarking,6406189924
new,MemoryChunk,0x16bb70600000,524288
timer-event-start,V8.GCIncrementalMarking,6406190724
timer-event-end,V8.GCIncrementalMarking,6406192029
new,MemoryChunk,0x18b8a0200000,524288
timer-event-start,V8.GCIncrementalMarking,6406192894
timer-event-end,V8.GCIncrementalMarking,6406194253
new,MemoryChunk,0x11c87c180000,524288
timer-event-start,V8.GCIncrementalMarking,6406195137
timer-event-end,V8.GCIncrementalMarking,6406196462
new,MemoryChunk,0x353b80280000,524288
timer-event-start,V8.GCIncrementalMarking,6406197381
timer-event-end,V8.GCIncrementalMarking,6406198513
new,MemoryChunk,0x991e5a80000,524288
timer-event-start,V8.GCIncrementalMarking,6406199347
timer-event-end,V8.GCIncrementalMarking,6406200659
new,MemoryChunk,0x77559500000,524288
timer-event-start,V8.GCIncrementalMarking,6406201554
timer-event-end,V8.GCIncrementalMarking,6406202952
new,MemoryChunk,0x51fcc580000,524288
timer-event-start,V8.GCIncrementalMarking,6406203842
timer-event-end,V8.GCIncrementalMarking,6406205229
new,MemoryChunk,0x11134ca80000,524288
timer-event-start,V8.GCIncrementalMarking,6406206124
timer-event-end,V8.GCIncrementalMarking,6406207561
new,MemoryChunk,0x17b32eb00000,524288
timer-event-start,V8.GCIncrementalMarking,6406208473
timer-event-end,V8.GCIncrementalMarking,6406209913
new,MemoryChunk,0xa7929400000,524288
timer-event-start,V8.GCIncrementalMarking,6406210795
timer-event-end,V8.GCIncrementalMarking,6406212249
new,MemoryChunk,0x1f76e7200000,524288
timer-event-start,V8.GCIncrementalMarking,6406213115
timer-event-end,V8.GCIncrementalMarking,6406214629
new,MemoryChunk,0x4bb9cd00000,524288
timer-event-start,V8.GCIncrementalMarking,6406215548
timer-event-end,V8.GCIncrementalMarking,6406216079
new,MemoryChunk,0x26fd04080000,524288
timer-event-start,V8.GCIncrementalMarking,6406216911
timer-event-end,V8.GCIncrementalMarking,6406217106
timer-event-start,V8.GCIncrementalMarkingFinalize,6406217606
timer-event-end,V8.GCIncrementalMarkingFinalize,6406217921
new,MemoryChunk,0x3e8b51000000,524288
timer-event-start,V8.GCIncrementalMarking,6406218332
timer-event-end,V8.GCIncrementalMarking,6406218348
timer-event-start,V8.GCFinalizeMC,6406218897
markcompact,begin,38,36462,1573929817653
markcompact,end,38,54306,1573929817670
timer-event-end,V8.GCFinalizeMC,6406237199
new,MemoryChunk,0x3e70a1a00000,524288
new,MemoryChunk,0x14c9e4180000,524288
new,MemoryChunk,0x335947c80000,524288
timer-event-start,V8.GCIncrementalMarkingStart,6406263779
timer-event-end,V8.GCIncrementalMarkingStart,6406264145
new,MemoryChunk,0x1bf6fd00000,524288
timer-event-start,V8.GCIncrementalMarking,6406264575
timer-event-end,V8.GCIncrementalMarking,6406266175
new,MemoryChunk,0x109d6f780000,524288
timer-event-start,V8.GCIncrementalMarking,6406267498
timer-event-end,V8.GCIncrementalMarking,6406269125
new,MemoryChunk,0xcf3b9200000,524288
timer-event-start,V8.GCIncrementalMarking,6406270226
timer-event-end,V8.GCIncrementalMarking,6406271868
new,MemoryChunk,0x33eb2c880000,524288
timer-event-start,V8.GCIncrementalMarking,6406272919
timer-event-end,V8.GCIncrementalMarking,6406274608
new,MemoryChunk,0x10c056a80000,524288
timer-event-start,V8.GCIncrementalMarking,6406275660
timer-event-end,V8.GCIncrementalMarking,6406277318
new,MemoryChunk,0x1846c1880000,524288
timer-event-start,V8.GCIncrementalMarking,6406278406
timer-event-end,V8.GCIncrementalMarking,6406280119
new,MemoryChunk,0x21eed5900000,524288
timer-event-start,V8.GCIncrementalMarking,6406281176
timer-event-end,V8.GCIncrementalMarking,6406282888
new,MemoryChunk,0x323ac6b80000,524288
timer-event-start,V8.GCIncrementalMarking,6406283954
timer-event-end,V8.GCIncrementalMarking,6406285682
new,MemoryChunk,0x3c2009d00000,524288
timer-event-start,V8.GCIncrementalMarking,6406286739
timer-event-end,V8.GCIncrementalMarking,6406288466
new,MemoryChunk,0x3d504cd00000,524288
timer-event-start,V8.GCIncrementalMarking,6406289535
timer-event-end,V8.GCIncrementalMarking,6406291291
new,MemoryChunk,0x235494980000,524288
timer-event-start,V8.GCIncrementalMarking,6406292373
timer-event-end,V8.GCIncrementalMarking,6406294127
new,MemoryChunk,0xecfc3600000,524288
timer-event-start,V8.GCIncrementalMarking,6406295191
timer-event-end,V8.GCIncrementalMarking,6406296997
new,MemoryChunk,0x1a2eae600000,524288
timer-event-start,V8.GCIncrementalMarking,6406298083
timer-event-end,V8.GCIncrementalMarking,6406299894
timer-event-end,V8.Execute,6406300603
应用端:
(1) // kGCTypeIncrementalMarking
[18:43:37.536(1573929817536752)][DEBUG]: GCPrologueCallback type: 4
[18:43:37.536(1573929817536955)][DEBUG]: GCEpilogCallback type: 4
Total: 203 micro
(2) // kGCTypeMarkSweepCompact
[18:43:37.539(1573929817539368)][DEBUG]: GCPrologueCallback type: 2
[18:43:37.559(1573929817559840)][DEBUG]: GCEpilogCallback type: 2
Total: 20472 micro
(3) // kGCTypeIncrementalMarking
[18:43:37.650(1573929817650874)][DEBUG]: GCPrologueCallback type: 4
[18:43:37.651(1573929817651154)][DEBUG]: GCEpilogCallback type: 4
Total: 280 micro
(4) // kGCTypeMarkSweepCompact
[18:43:37.652(1573929817652160)][DEBUG]: GCPrologueCallback type: 2
[18:43:37.670(1573929817670422)][DEBUG]: GCEpilogCallback type: 2
Total: 18262 micro
因此,总共 39217 微秒或 40 毫秒。
这样读取V8日志太复杂了。所以我通过测量之间的时间对其进行了一些后处理timer-event-start
/timer-event-end
events.
(V8.GCIncrementalMarking, 523)
(V8.GCIncrementalMarking, 2001)
(V8.GCIncrementalMarking, 2145)
(V8.GCIncrementalMarking, 2190)
(V8.GCIncrementalMarking, 2079)
(V8.GCIncrementalMarking, 799)
(V8.GCIncrementalMarking, 2024)
(V8.GCIncrementalMarking, 2207)
(V8.GCIncrementalMarking, 2103)
(V8.GCIncrementalMarking, 2157)
(V8.GCIncrementalMarking, 2128)
(V8.GCIncrementalMarking, 2098)
(V8.GCIncrementalMarking, 2135)
(V8.GCIncrementalMarking, 2156)
(V8.GCIncrementalMarking, 2181)
(V8.GCIncrementalMarking, 2114)
(V8.GCIncrementalMarking, 1507)
(V8.GCIncrementalMarking, 119)
(V8.GCIncrementalMarkingFinalize, 244) (1)
(V8.GCIncrementalMarking, 24)
(V8.GCFinalizeMC, 20507) (2)
(V8.GCIncrementalMarkingStart, 428)
(V8.GCIncrementalMarking, 1084)
(V8.GCIncrementalMarking, 1643)
(V8.GCIncrementalMarking, 1639)
(V8.GCIncrementalMarking, 1638)
(V8.GCIncrementalMarking, 1663)
(V8.GCIncrementalMarking, 1696)
(V8.GCIncrementalMarking, 1691)
(V8.GCIncrementalMarking, 1691)
(V8.GCIncrementalMarking, 1748)
(V8.GCIncrementalMarking, 1723)
(V8.GCIncrementalMarking, 1740)
(V8.GCIncrementalMarking, 1749)
(V8.GCIncrementalMarking, 1753)
(V8.GCIncrementalMarking, 1750)
(V8.GCIncrementalMarking, 709)
(V8.GCIncrementalMarking, 447)
(V8.GCIncrementalMarking, 752)
(V8.GCIncrementalMarking, 1305)
(V8.GCIncrementalMarking, 1359)
(V8.GCIncrementalMarking, 1325)
(V8.GCIncrementalMarking, 1132)
(V8.GCIncrementalMarking, 1312)
(V8.GCIncrementalMarking, 1398)
(V8.GCIncrementalMarking, 1387)
(V8.GCIncrementalMarking, 1437)
(V8.GCIncrementalMarking, 1440)
(V8.GCIncrementalMarking, 1454)
(V8.GCIncrementalMarking, 1514)
(V8.GCIncrementalMarking, 531)
(V8.GCIncrementalMarking, 195)
(V8.GCIncrementalMarkingFinalize, 315) (3)
(V8.GCIncrementalMarking, 16)
(V8.GCFinalizeMC, 18302) (4)
(V8.GCIncrementalMarkingStart, 366)
(V8.GCIncrementalMarking, 1600)
(V8.GCIncrementalMarking, 1627)
(V8.GCIncrementalMarking, 1642)
(V8.GCIncrementalMarking, 1689)
(V8.GCIncrementalMarking, 1658)
(V8.GCIncrementalMarking, 1713)
(V8.GCIncrementalMarking, 1712)
(V8.GCIncrementalMarking, 1728)
(V8.GCIncrementalMarking, 1727)
(V8.GCIncrementalMarking, 1756)
(V8.GCIncrementalMarking, 1754)
(V8.GCIncrementalMarking, 1806)
(V8.GCIncrementalMarking, 1811)
(Total, 135996)
正如你所看到的,我们只能匹配 4 个案例,但是很多GCIncrementalMarking
活动未被注意到。
真实的总时间等于136ms。远远超过 40 毫秒!,我们能够在应用程序端测量。
我知道奥里诺科河和并行方法,但我不知道是否调用GCIncrementalMarking
是否阻止代码执行。
我们已经多次注意到相同的情况,并且在所有情况下,代码终止的原因都是与 V8 日志文件相比,应用程序端的 GC 测量不正确。
这是故意的吗?我们不能那么信任 GC 回调吗?或者我错过了什么?
作为临时解决方案,我们将 V8 降级为5.6.316
而且效果还不错..
6.7.240
有新的 GC 方法,这可能是该问题的根源吗?
PS. --single-threaded-gc
for 6.7.240
也没有帮助
聚苯硫醚。一些与V8和GC逻辑相关的代码:
void cnode::V8Runner::init() {
v8::V8::InitializeICU();
v8::Platform *platform = v8::platform::CreateDefaultPlatform();
v8::V8::InitializePlatform(platform);
v8::V8::Initialize();
auto flags = "--log --log-all --logfile=/tmp/v8.log --nolazy";
auto isolate = cnode::V8Runner::getIsolate();
isolate->AddGCPrologueCallback(cnode::V8Runner::_GCPrologue);
isolate->AddGCEpilogueCallback(cnode::V8Runner::_GCEpilog);
}
void cnode::V8Runner::_GCPrologue(v8::Isolate *isolate, v8::GCType type,
v8::GCCallbackFlags flags) {
cnode::V8Runner::_GCPrologueTimePoint = std::chrono::high_resolution_clock::now();
cnode::V8Runner::_GCEpilogTimePoint = std::chrono::high_resolution_clock::now();
LOG_DEBUG("GCPrologueCallback type: %d", type);
}
void cnode::V8Runner::_GCEpilog(v8::Isolate *isolate, v8::GCType type,
v8::GCCallbackFlags flags) {
cnode::V8Runner::_GCEpilogTimePoint = std::chrono::high_resolution_clock::now();
std::chrono::milliseconds _GCPrologueTimePointMs = std::chrono::duration_cast<std::chrono::milliseconds>(
cnode::V8Runner::_GCPrologueTimePoint.time_since_epoch());
std::chrono::milliseconds _GCEpilogTimePointMs = std::chrono::duration_cast<std::chrono::milliseconds>(
cnode::V8Runner::_GCEpilogTimePoint.time_since_epoch());
const int diff = _GCEpilogTimePointMs.count() - _GCPrologueTimePointMs.count();
cnode::V8Runner::_currentGCActionMs += diff;
cnode::V8Runner::_GCPrologueTimePoint = std::chrono::high_resolution_clock::now();
cnode::V8Runner::_GCEpilogTimePoint = std::chrono::high_resolution_clock::now();
LOG_DEBUG("GCEpilogCallback type: %d", type);
}
购买力平价。
在这篇文章之后,我决定使用手动调用来重新检查这一点Isolate::LowMemoryNotification()
每次代码执行后。
原始 V8 日志:
api,v8::Context::New
api,v8::FunctionTemplate::New
api,v8::ObjectTemplate::New
[api,v8::FunctionTemplate::New]
api,v8::String::NewFromUtf8
api,v8::JSON::Parse
[new,MemoryChunk,0x1940b7d00000,524288]
timer-event-start,V8.GCIncrementalMarkingStart,4351782723
timer-event-end,V8.GCIncrementalMarkingStart,4351783066
new,MemoryChunk,0x106dca200000,524288
timer-event-start,V8.GCIncrementalMarking,4351783463
timer-event-end,V8.GCIncrementalMarking,4351785131
new,MemoryChunk,0x225019c00000,524288
timer-event-start,V8.GCIncrementalMarking,4351786485
timer-event-end,V8.GCIncrementalMarking,4351788194
new,MemoryChunk,0xdfc50c80000,524288
timer-event-start,V8.GCIncrementalMarking,4351789202
timer-event-end,V8.GCIncrementalMarking,4351790879
new,MemoryChunk,0x26861a780000,524288
timer-event-start,V8.GCIncrementalMarking,4351791905
timer-event-end,V8.GCIncrementalMarking,4351793611
new,MemoryChunk,0x44086a00000,524288
timer-event-start,V8.GCIncrementalMarking,4351794615
timer-event-end,V8.GCIncrementalMarking,4351796319
new,MemoryChunk,0x4debd600000,524288
timer-event-start,V8.GCIncrementalMarking,4351797315
timer-event-end,V8.GCIncrementalMarking,4351799066
new,MemoryChunk,0x2db69c500000,524288
timer-event-start,V8.GCIncrementalMarking,4351800060
timer-event-end,V8.GCIncrementalMarking,4351801814
new,MemoryChunk,0x1f1825000000,524288
timer-event-start,V8.GCIncrementalMarking,4351802804
timer-event-end,V8.GCIncrementalMarking,4351804535
new,MemoryChunk,0x86246080000,524288
timer-event-start,V8.GCIncrementalMarking,4351805573
timer-event-end,V8.GCIncrementalMarking,4351807383
new,MemoryChunk,0xfc3bb580000,524288
timer-event-start,V8.GCIncrementalMarking,4351808377
timer-event-end,V8.GCIncrementalMarking,4351810192
new,MemoryChunk,0x10451e500000,524288
timer-event-start,V8.GCIncrementalMarking,4351811223
timer-event-end,V8.GCIncrementalMarking,4351813019
new,MemoryChunk,0x16e643c00000,524288
timer-event-start,V8.GCIncrementalMarking,4351814010
timer-event-end,V8.GCIncrementalMarking,4351815842
new,MemoryChunk,0x2a4379600000,524288
timer-event-start,V8.GCIncrementalMarking,4351816837
timer-event-end,V8.GCIncrementalMarking,4351818621
new,MemoryChunk,0x18436f400000,524288
timer-event-start,V8.GCIncrementalMarking,4351819650
timer-event-end,V8.GCIncrementalMarking,4351821491
new,MemoryChunk,0x3b377700000,524288
timer-event-start,V8.GCIncrementalMarking,4351822503
timer-event-end,V8.GCIncrementalMarking,4351824007
new,MemoryChunk,0x1f2f22600000,524288
timer-event-start,V8.GCIncrementalMarking,4351825011
timer-event-end,V8.GCIncrementalMarking,4351825827
new,MemoryChunk,0x1cd733a80000,524288
timer-event-start,V8.GCIncrementalMarking,4351826871
timer-event-end,V8.GCIncrementalMarking,4351827291
new,MemoryChunk,0x3cf039a80000,524288
timer-event-start,V8.GCIncrementalMarking,4351828058
timer-event-end,V8.GCIncrementalMarking,4351828500
new,MemoryChunk,0x31ae7100000,524288
timer-event-start,V8.GCIncrementalMarking,4351829286
timer-event-end,V8.GCIncrementalMarking,4351830586
new,MemoryChunk,0x2265e4c00000,524288
timer-event-start,V8.GCIncrementalMarking,4351831462
timer-event-end,V8.GCIncrementalMarking,4351832806
new,MemoryChunk,0x34586ae00000,524288
timer-event-start,V8.GCIncrementalMarking,4351833700
timer-event-end,V8.GCIncrementalMarking,4351835122
new,MemoryChunk,0x21c0aa580000,524288
timer-event-start,V8.GCIncrementalMarking,4351836000
timer-event-end,V8.GCIncrementalMarking,4351837409
new,MemoryChunk,0x2d29cda00000,524288
timer-event-start,V8.GCIncrementalMarking,4351838280
timer-event-end,V8.GCIncrementalMarking,4351839701
new,MemoryChunk,0x216cbbb80000,524288
timer-event-start,V8.GCIncrementalMarking,4351840569
timer-event-end,V8.GCIncrementalMarking,4351842015
new,MemoryChunk,0x1fb82e480000,524288
timer-event-start,V8.GCIncrementalMarking,4351842910
timer-event-end,V8.GCIncrementalMarking,4351844380
new,MemoryChunk,0x329529f00000,524288
timer-event-start,V8.GCIncrementalMarking,4351845255
timer-event-end,V8.GCIncrementalMarking,4351846654
new,MemoryChunk,0x957ccf80000,524288
timer-event-start,V8.GCIncrementalMarking,4351847553
timer-event-end,V8.GCIncrementalMarking,4351848991
new,MemoryChunk,0x2df008e00000,524288
timer-event-start,V8.GCIncrementalMarking,4351849864
timer-event-end,V8.GCIncrementalMarking,4351851358
new,MemoryChunk,0x8be2be80000,524288
timer-event-start,V8.GCIncrementalMarking,4351852237
timer-event-end,V8.GCIncrementalMarking,4351853720
new,MemoryChunk,0x146846980000,524288
timer-event-start,V8.GCIncrementalMarking,4351854588
timer-event-end,V8.GCIncrementalMarking,4351856080
new,MemoryChunk,0x367cfe280000,524288
timer-event-start,V8.GCIncrementalMarking,4351856969
timer-event-end,V8.GCIncrementalMarking,4351858491
new,MemoryChunk,0x6ed38180000,524288
timer-event-start,V8.GCIncrementalMarking,4351859382
timer-event-end,V8.GCIncrementalMarking,4351860900
new,MemoryChunk,0xfbd5f600000,524288
timer-event-start,V8.GCIncrementalMarking,4351861805
timer-event-end,V8.GCIncrementalMarking,4351863367
new,MemoryChunk,0x1a5e01680000,524288
timer-event-start,V8.GCIncrementalMarking,4351864277
timer-event-end,V8.GCIncrementalMarking,4351865092
new,MemoryChunk,0x24120d700000,524288
timer-event-start,V8.GCIncrementalMarking,4351865984
timer-event-end,V8.GCIncrementalMarking,4351866048
new,MemoryChunk,0x125d39480000,524288
timer-event-start,V8.GCIncrementalMarking,4351866808
timer-event-end,V8.GCIncrementalMarking,4351866824
timer-event-start,V8.GCIncrementalMarkingFinalize,4351867246
timer-event-end,V8.GCIncrementalMarkingFinalize,4351867419
new,MemoryChunk,0x2f31d9400000,524288
timer-event-start,V8.GCIncrementalMarking,4351867767
timer-event-end,V8.GCIncrementalMarking,4351867774
timer-event-start,V8.GCFinalizeMC,4351869855
markcompact,begin,7143,825650,1575032707066
markcompact,end,7143,846265,1575032707086
timer-event-end,V8.GCFinalizeMC,4351890363
[new,MemoryChunk,0x19b52bb00000,524288]
timer-event-start,V8.GCLowMemoryNotification,4351984850
timer-event-start,V8.GCCompactor,4351984910
markcompact,begin,7143,949018,1575032707181
[delete,MemoryChunk,0xd202f700000]
markcompact,end,7144,188469,1575032707268
timer-event-end,V8.GCCompactor,4352073048
[delete,MemoryChunk,0x1c887fa80000]
timer-event-start,V8.GCCompactor,4352073343
markcompact,begin,7144,192691,1575032707270
new,MemoryChunk,0x33c543500000,524288
new,MemoryChunk,0xd4241800000,524288
[sfi-move,0x8b6f5421390,0xd424181d470]
[delete,MemoryChunk,0x1455b1780000]
markcompact,end,7144,453893,1575032707371
timer-event-end,V8.GCCompactor,4352175676
delete,MemoryChunk,0x25fae9b80000
delete,MemoryChunk,0x2590e9700000
timer-event-end,V8.GCLowMemoryNotification,4352175844
api,v8::ObjectTemplate::New
api,v8::FunctionTemplate::New
api,v8::String::NewFromUtf8
应用日志:
(1) // kGCTypeIncrementalMarking
[13:05:07.063(1575032707063270)][DEBUG]: GCPrologueCallback type: 4
[13:05:07.063(1575032707063418)][DEBUG]: GCEpilogCallback type: 4
Total: 148micro
(2) // kGCTypeMarkSweepCompact
[13:05:07.065(1575032707065876)][DEBUG]: GCPrologueCallback type: 2
[13:05:07.086(1575032707086356)][DEBUG]: GCEpilogCallback type: 2
Total: 20480 micro
(3) // kGCTypeMarkSweepCompact
[13:05:07.180(1575032707180925)][DEBUG]: GCPrologueCallback type: 2
[13:05:07.269(1575032707269036)][DEBUG]: GCEpilogCallback type: 2
(4) // kGCTypeMarkSweepCompact
[13:05:07.269(1575032707269366)][DEBUG]: GCPrologueCallback type: 2
[13:05:07.371(1575032707371667)][DEBUG]: GCEpilogCallback type: 2
后处理后的V8 Log:
(V8.GCIncrementalMarkingStart, 343) (1)?
(V8.GCIncrementalMarking, 1668)
(V8.GCIncrementalMarking, 1709)
(V8.GCIncrementalMarking, 1677)
(V8.GCIncrementalMarking, 1706)
(V8.GCIncrementalMarking, 1704)
(V8.GCIncrementalMarking, 1751)
(V8.GCIncrementalMarking, 1754)
(V8.GCIncrementalMarking, 1731)
(V8.GCIncrementalMarking, 1810)
(V8.GCIncrementalMarking, 1815)
(V8.GCIncrementalMarking, 1796)
(V8.GCIncrementalMarking, 1832)
(V8.GCIncrementalMarking, 1784)
(V8.GCIncrementalMarking, 1841)
(V8.GCIncrementalMarking, 1504)
(V8.GCIncrementalMarking, 816)
(V8.GCIncrementalMarking, 420)
(V8.GCIncrementalMarking, 442)
(V8.GCIncrementalMarking, 1300)
(V8.GCIncrementalMarking, 1344)
(V8.GCIncrementalMarking, 1422)
(V8.GCIncrementalMarking, 1409)
(V8.GCIncrementalMarking, 1421)
(V8.GCIncrementalMarking, 1446)
(V8.GCIncrementalMarking, 1470)
(V8.GCIncrementalMarking, 1399)
(V8.GCIncrementalMarking, 1438)
(V8.GCIncrementalMarking, 1494)
(V8.GCIncrementalMarking, 1483)
(V8.GCIncrementalMarking, 1492)
(V8.GCIncrementalMarking, 1522)
(V8.GCIncrementalMarking, 1518)
(V8.GCIncrementalMarking, 1562)
(V8.GCIncrementalMarking, 815)
(V8.GCIncrementalMarking, 64)
(V8.GCIncrementalMarking, 16)
(V8.GCIncrementalMarkingFinalize, 173)
(V8.GCIncrementalMarking, 7)
(V8.GCFinalizeMC, 20508) (2)
// call to LowMemoryNotification
(V8.GCCompactor, 88138) (3)
(V8.GCCompactor, 102333) (4)
(V8.GCLowMemoryNotification, 190994)
(Total, 452871)
当我看到这个时,我的第一个想法是 - V8.GCLowMemoryNotification (190994) 包括 V8.GCCompactor(88138) 和 V8.GCCompactor(102333)..毕竟 (88138 + 102333)
所以,大概V8.GCIncrementalMarking
也被纳入V8.GCFinalizeMC
。但事实证明并非如此——20508
远小于数量GCIncrementalMarking
s 值(50555
).
这个故事最终的结果都是一样的——执行超时。代码的时间限制等于200ms
.
Call to LowMemoryNotification
不包括在watchdog
监控。所以452871 - 190994 = 261877
.
请记住,我们尊重 GC 活动,所以261877 - 20508 = 241369
。仍然大于200ms。
但是,如果我们开始计算所有V8.GCIncrementalMarking
活动 (50555
微秒),最终结果将是241369 - 50555 = 190814
. 190ms
- 没有超时!
我仍然认为V8(6.7.240
)在 GC 活动方面没有提供足够的准确性。