1234 |
[ ~]# cat gc.log.
0 | grep
‘Full GC‘
1.652
: [Full GC (System)
1.652
: [CMS: 0K->21718K(262144K),
0.0837910 secs] 48398K->21718K(458752K), [CMS Perm : 16462K->16457K(21248K)],
0.0841650 secs] [Times: user=
0.08 sys=
0.00
, real=
0.08 secs]
664643.879
: [GC
664643.879
: [ParNew: 134434K->3202K(196608K),
0.0068030 secs] 327839K->196659K(458752K) icms_dc=
0 ,
0.0070080 secs] [Times: user=
0.03 sys=
0.00
, real=
0.01 secs]
|
1.625, 664643.879 is the time that the GC occurred, the number of seconds elapsed since the Java Virtual machine was started.
"[GC" and "[Full GC" indicate the type of GC pauses, rather than distinguishing between the Cenozoic GC and the old-age GC.
The full GC will occur Stop-the-world (STW). If the full GC triggered by System.GC () is called, "[Full GC (System)" is displayed
[Defnew, [tenured, [perm indicates the area where GC occurs:
[Defnew:serial Collector in the Cenozoic
[Parnew:parnew collector Cenozoic
[Psyounggen:parallel scanvenge collector Cenozoic
[Cms:cms collector old age
[Tenured:serial collector old age
[Perm,[cms Perm: Permanent generation
1 |
134434K->3202K(196608K) 含义: “GC前内存区已使用容量->GC后内存区已使用容量(该内存区域总容量)” |
1 |
[Times: user= 0.03 sys= 0.00 , real= 0.01 secs] 含义:user,sys,real分别表示用户消耗CPU时间、内核消耗CPU时间、操作从开始到结束所经过的墙钟时间(wall clock time)<br>CPU时间与墙钟时间的区别:墙钟时间包括各种非运算等待时间,如IO阻塞等待,而CPU不包括这些时间。 |
java-Performance Tuning-Understanding GC Logs