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这是我的应用程序的 VM OPS

-Xms7500m
-Xmx7500m
-Xmn4g
-XX:MaxPermSize=192m
-XX:TargetSurvivorRatio=80
-XX:+AggressiveOpts
-XX:+UseFastAccessorMethods
-XX:+UseParNewGC
-XX:+UseConcMarkSweepGC
-XX:+CMSParallelRemarkEnabled
-XX:+UseCMSInitiatingOccupancyOnly
-XX:ConcGCThreads=6
-XX:+PrintGCApplicationStoppedTime
-XX:+PrintGCCause
-verbose:gc
-XX:+PrintGCTimeStamps
-XX:+PrintGCDetails
-XX:+PrintGCDateStamps
-XX:+PrintTenuringDistribution
-XX:+HeapDumpOnOutOfMemoryError

5 天内发生 3 次并发模式异常。应用程序仍在运行文件，内存也可用。

2020-04-16T18:57:47.575-0400: 100509.755: [CMS-concurrent-abortable-preclean-start]
2020-04-16T18:57:51.701-0400: 100513.881: [GC (Allocation Failure)2020-04-16T18:57:51.702-0400: 100513.881: [ParNew (promotion failed)
Desired survivor size 343565920 bytes, new threshold 6 (max 6)
- age   1:   91240280 bytes,   91240280 total
- age   2:   52703592 bytes,  143943872 total
- age   3:   26770336 bytes,  170714208 total
- age   4:   29495504 bytes,  200209712 total
- age   5:    9595480 bytes,  209805192 total
- age   6:   24205808 bytes,  234011000 total
: 3710667K->3614781K(3774912K), 1.1252750 secs]2020-04-16T18:57:52.827-0400: 100515.007: [CMS CMS: abort preclean due to time 2020-04-16T18:57:52.894-0400: 100515.074: [CMS-concurrent-abortable-preclean: 4.174/5.319 secs] [Times: user=14.39 sys=0.29, real=5.32 secs]
(concurrent mode failure): 3227087K->1442206K(3485696K), 8.0583310 secs] 6926256K->1442206K(7260608K), [CMS Perm : 105501K->105321K(176020K)], 9.1844190 secs] [Times: user=9.41 sys=0.01, real=9.18 secs]
--
2020-04-19T18:05:09.581-0400: 356551.761: [CMS-concurrent-abortable-preclean-start]
2020-04-19T18:05:11.759-0400: 356553.939: [GC (Allocation Failure)2020-04-19T18:05:11.760-0400: 356553.939: [ParNew (promotion failed)
Desired survivor size 343565920 bytes, new threshold 6 (max 6)
- age   1:   95822816 bytes,   95822816 total
- age   2:   24589528 bytes,  120412344 total
- age   3:   28175272 bytes,  148587616 total
- age   4:   24536120 bytes,  173123736 total
- age   5:   23041104 bytes,  196164840 total
- age   6:   12194152 bytes,  208358992 total
: 3670487K->3606232K(3774912K), 0.9360540 secs]2020-04-19T18:05:12.696-0400: 356554.875: [CMS2020-04-19T18:05:12.758-0400: 356554.938: [CMS-concurrent-abortable-preclean: 2.224/3.177 secs] [Times: user=10.62 sys=0.17, real=3.18 secs]
(concurrent mode failure): 3233090K->1492098K(3485696K), 7.9204130 secs] 6896158K->1492098K(7260608K), [CMS Perm : 105666K->105467K(176212K)], 8.8569600 secs] [Times: user=9.08 sys=0.01, real=8.86 secs]
--
2020-04-22T19:07:04.975-0400: 619467.155: Total time for which application threads were stopped: 0.0047280 seconds
2020-04-22T19:07:07.174-0400: 619469.354: [GC (Allocation Failure)2020-04-22T19:07:07.174-0400: 619469.354: [ParNew (promotion failed)
Desired survivor size 343565920 bytes, new threshold 6 (max 6)
- age   1:   98089096 bytes,   98089096 total
- age   2:   31239384 bytes,  129328480 total
- age   3:   29372368 bytes,  158700848 total
- age   4:   27791800 bytes,  186492648 total
- age   5:   19365904 bytes,  205858552 total
- age   6:   35928016 bytes,  241786568 total
: 3643909K->3678567K(3774912K), 0.9460110 secs]2020-04-22T19:07:08.121-0400: 619470.300: [CMS2020-04-22T19:07:08.234-0400: 619470.413: [CMS-concurrent-abortable-preclean: 2.612/3.582 secs] [Times: user=12.78 sys=0.18, real=3.58 secs]
(concurrent mode failure): 3230258K->1503933K(3485696K), 8.8236640 secs] 6862317K->1503933K(7260608K), [CMS Perm : 105907K->105647K(176596K)], 9.7702040 secs] [Times: user=10.06 sys=0.00, real=9.77 secs]

应用程序在过去一周内没有 FullGC

2020-04-15T15:03:29.193-0400: 51.372: [Full GC (Permanent Generation Full)2020-04-15T15:03:29.193-0400: 51.373: [CMS: 771051K->1044286K(3485696K), 4.2744340 secs] 1915012K->1044286K(7260608K), [CMS Perm : 101698K->101581K(102128K)], 4.2749400 secs] [Times: user=4.18 sys=0.11, real=4.28 secs]

为什么并发模式失败异常会在

  1. 没有频繁的 Full GC

  2. GC 后正在回收内存

    3227087K->1442206K(3485696K), 8.0583310 secs] 6926256K->1442206K(7260608K)
3233090K->1492098K(3485696K), 7.9204130 secs] 6896158K->1492098K(7260608K)
3230258K->1503933K(3485696K), 8.8236640 secs] 6862317K->1503933K(7260608K)

节点配置：8 核 CPU，12 GB RAM RHEL VM，JDK 1.7.0_45

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1 回答 1

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来自Java平台的第8章并发标记扫描（CMS）收集器，标准版HotSpot虚拟机垃圾收集调优指南：

并发模式失败

CMS 收集器使用一个或多个与应用程序线程同时运行的垃圾收集器线程，目的是在老生代变满之前完成对它的收集。如前所述，在正常操作中，CMS 收集器在应用程序线程仍在运行的情况下完成大部分跟踪和清扫工作，因此应用程序线程只会看到短暂的暂停。但是，如果 CMS 收集器无法在年老代填满之前完成对不可达对象的回收，或者如果在年老代中的可用空闲空间块无法满足分配，则应用程序将暂停并完成收集所有应用程序线程都停止了。无法同时完成收集被称为并发模式失败并指示需要调整 CMS 收集器参数。如果并发收集被显式垃圾收集 ( System.gc()) 或需要为诊断工具提供信息的垃圾收集中断，则报告并发模式中断。

这意味着，当时，您的应用程序生成垃圾的速度比收集器线程回收它们的速度要快，并且/或者正在使用太多 CPU，以至于收集器线程没有时间完成工作。

于 2020-04-24T04:52:03.837 回答