【筆記】Minor GC 的gc.log解析
阿新 • • 發佈：2018-12-10
2016-08-23T02:23:07.219-02001: 64.3222:[GC3(Allocation Failure4) 64.322: [ParNew5: 613404K->68068K6(613440K)7, 0.1020465 secs8] 10885349K->10880154K9(12514816K)10, 0.1021309 secs11][Times: user=0.78 sys=0.01, real=0.11 secs]12
- 2016-08-23T02:23:07.219-0200 – GC發生的時間；
- 64.322 – GC開始，相對JVM啟動的相對時間，單位是秒；
- GC – 區別MinorGC和FullGC的標識，這次代表的是MinorGC;
- Allocation Failure – MinorGC的原因，在這個case裡邊，由於年輕代不滿足申請的空間，因此觸發了MinorGC;
- ParNew – 收集器的名稱，它預示了年輕代使用一個並行的 mark-copy stop-the-world 垃圾收集器；
- 613404K->68068K – 收集前後年輕代的使用情況；
- (613440K) – 整個年輕代的容量；
- 0.1020465 secs – 這個解釋用原滋原味的解釋：Duration for the collection w/o final cleanup.
- 10885349K->10880154K – 收集前後整個堆的使用情況；
- (12514816K) – 整個堆的容量；
- 0.1021309 secs – ParNew收集器標記和複製年輕代活著的物件所花費的時間（包括和老年代通訊的開銷、物件晉升到老年代時間、垃圾收集週期結束一些最後的清理物件等的花銷）；
- [Times: user=0.78 sys=0.01, real=0.11 secs] – GC事件在不同維度的耗時，具體的用英文解釋起來更加合理:
- user – Total CPU time that was consumed by Garbage Collector threads during this collection
- sys – Time spent in OS calls or waiting for system event
- real – Clock time for which your application was stopped. With Parallel GC this number should be close to (user time + system time) divided by the number of threads used by the Garbage Collector. In this particular case 8 threads were used. Note that due to some activities not being parallelizable, it always exceeds the ratio by a certain amount.