是否是CMS-concurrent-preclean中止导致了CMS-Concurrent-Sweep的耗时执行？

Question

java版本“1.6.0_21”java(TM)SE运行时环境（build 1.6.021-B07)java HotSpot(TM)64位服务器VM（build 17.0-B17，混合模式）

jvm配置：

-server-xx:+DoesCapeAnalysis-xx:+CmSparalleLeserveEnabled-xx:+UseBiasedLocking-xx:+UseBiasedLocking-xx:+UseConcMarkSweepGC-xx:+UseParNewGC-xx:+CmsConcurrentMtenabled-xx:+UseParNewGC

-djavax.xml.parsers.documentbuilderfactory=org.apache.xerces.jaxp.documentbuilderfactoryimpl-verbose：gc-xx:+printgcdetails-xx:+printgctimestamps-xx:+heapdumponoutofmemoryerror-djava.net.preferipv4stack=true-dorg.apache.el.parser.coerce_to_zero=false

32163.991: [CMS-concurrent-mark-start]
32165.339: [CMS-concurrent-mark: 1.318/1.347 secs] [Times: user=6.49 sys=0.39, real=1.35 secs] 
32165.339: [CMS-concurrent-preclean-start]
32165.370: [CMS-concurrent-preclean: 0.030/0.031 secs] [Times: user=0.03 sys=0.00, real=0.03 secs] 
32165.370: [CMS-concurrent-abortable-preclean-start]  CMS: abort preclean due to time 32170.796: [CMS-concurrent-abortable-preclean:
3.737/5.426 secs] [Times: user=10.70 sys=0.31, real=5.43 secs] 
32170.873: [GC[YG occupancy: 754283 K (1887488 K)]32170.873: [Rescan (parallel) , 0.1046140 secs]32170.978: [weak refs processing,
0.0612460 secs] [1 CMS-remark: 5824525K(6291456K)] 6578809K(8178944K), 0.1700560 secs] [Times: user=1.51 sys=0.02, real=0.17 secs] 
32171.100: [CMS-concurrent-sweep-start]
32173.805: [GC 32173.805: [ParNew: 1887488K->209664K(1887488K), 0.3380510 secs] 6928845K->5305271K(8178944K), 0.3385670 secs] [Times: user=1.25 sys=0.05, real=0.34 secs] 
32176.970: [GC 32176.970: [ParNew: 1887488K->209664K(1887488K), 0.1728610 secs] 5660997K->4005785K(8178944K), 0.1734010 secs] [Times: user=1.09 sys=0.10, real=0.17 secs] 
32179.315: [CMS-concurrent-sweep: 6.088/8.215 secs] [Times: user=48.00 sys=2.80, real=8.22 secs] 
32179.315: [CMS-concurrent-reset-start]
32179.507: [CMS-concurrent-reset: 0.192/0.192 secs] [Times: user=1.51 sys=0.22, real=0.19 secs]

是否是CMS-concurrent-preclean中止导致了CMS-Concurrent-Sweep的耗时执行？是否会对用户造成48秒世界停止的影响？从上面的gc日志推断出来的是什么。

Answer 1

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所有表示为CMS-concurrent-*的阶段都是并发的，因此不是STW暂停。CMS Initial Mark和CMS Final Remark是由并发循环引起的停顿。当然，young gen收集器有自己的STW暂停

user=xxx与time命令的输出具有相同的语义。它是指进程调度的核心时间，它与经过的墙时间有很大的关系。real是您在对STW暂停的持续时间感兴趣时需要查找的内容。

从上面的gc日志推断出来的是什么。