JAVA垃圾收集参数与日志格式

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-XX:-PrintGC

默认不启用

开启GC 日志打印。

例如：

[Full GC 131115K->7482K(1015808K), 0.1633180 secs]

该选项可通过 com.sun.management.HotSpotDiagnosticMXBean API 和 Jconsole 动态启用。

详见 http://java.sun.com/developer/technicalArticles/J2SE/monitoring/#Heap_Dump

-XX:-PrintGCDetails

1.4.0 引入，默认不启用

打印GC 回收的细节。

例如：

[Full GC (System) [Tenured: 0K->2394K(466048K), 0.0624140 secs] 30822K->2394K(518464K), [Perm : 10443K->10443K(16384K)], 0.0625410 secs] [Times: user=0.05 sys=0.01, real=0.06 secs]

该选项可通过 com.sun.management.HotSpotDiagnosticMXBean API 和 Jconsole 动态启用。

详见 http://java.sun.com/developer/technicalArticles/J2SE/monitoring/#Heap_Dump

-XX:-PrintGCTimeStamps

默认不启用

打印GC 停顿耗时。

例如：

2.744 : [Full GC (System) 2.744: [Tenured: 0K->2441K(466048K), 0.0598400 secs] 31754K->2441K(518464K), [Perm : 10717K->10717K(16384K)], 0.0599570 secs] [Times: user=0.06 sys=0.00, real=0.06

secs]

该选项可通过 com.sun.management.HotSpotDiagnosticMXBean API 和 Jconsole 动态启用。

详见 http://java.sun.com/developer/technicalArticles/J2SE/monitoring

The minor collection output for these options produce output of the form

[GC [<collector>: <starting occupancy1> -> <ending occupancy1>, <pause time1> secs] <starting occupancy3> -> <ending occupancy3>, <pause time3> secs]

where

<collector> is an internal name for the collector used in the minor collection

<starting occupancy1> is the occupancy of the young generation before the collection

<ending occupancy1> is the occupancy of the young generation after the collection

<pause time1> is the pause time in seconds for the minor collection.

<starting occupancy3> is the occupancy of the entire heap before the collection

<ending occupancy3> is the occupancy of the entire heap after the collection

<pause time3> is the pause time for the entire garbage collection. This would include the time for a major collection is one was done.

（1）Java SE 6 HotSpot[tm] Virtual Machine Garbage Collection Tuning

（2）Diagnosing a Garbage Collection problem