Java 8中的默认Full GC间隔是多少? [英] What is the default Full GC interval in Java 8
问题描述
VM启动参数为:
-server
-Xms4g
-Xmx8g
以下参数是不是激活的:
-Dsun.rmi.dgc.client.gcInterval = 3600000
-Dsun.rmi.dgc.server.gcInterval = 3600000
那么Java 8中的默认完全GC时间间隔是多少?我如何将其配置为动态的?
-Dsun.rmi.dgc.server.gcInterval = 3600000
未被激活。但是,这些属性是这些属性的默认值;即,如果您不指定属性值,则会得到的值。
参考:Oracle的 sun.rmi Properties documentation。
那么Java 8中默认的完整GC时间间隔是多少?
请参阅上面的DCG触发的完整GC。除此之外,当请求时(通过 System.gc()
call)或者当JVM决定这是必要的。如果您不使用RMI,则没有固定间隔。
...以及如何将其配置为动态?
如果你的意思是,你如何阻止RMI每小时触发一次完整的GC: 一种方法是为这些属性指定(很多)较大的值。另一种方法是启动JVM与
-XX:+ DisableExplicitGC
标志。注意:这将禁止对 System.gc()
的全部调用,而不仅仅是RMI的DGC调用。
We noticed a strange behavior on our production server (JavaEE, Wildfly 10). The Java VM do once per hour Full GC although there is still enough memory available.
The VM start parameters are:
-server
-Xms4g
-Xmx8g
The following parameters are not activated:
-Dsun.rmi.dgc.client.gcInterval=3600000
-Dsun.rmi.dgc.server.gcInterval=3600000
So what is the default Full GC interval in Java 8 and how can I configure it to be dynamic?
You say that
-Dsun.rmi.dgc.client.gcInterval=3600000
-Dsun.rmi.dgc.server.gcInterval=3600000
are not "activated". However, those are the default values for those properties; i.e. the values that you get if you DON'T specify values for the properties.
Reference: Oracle's sun.rmi Properties documentation.
So what is the default Full GC interval in Java 8
See above for the DCG triggered full GCs.
Apart from that, a full GC happens when requested (by a System.gc()
call) or when the JVM decides it is necessary. There is no fixed interval if you are not using RMI.
... and how can I configure it to be dynamic?
If you mean, how can you stop RMI from triggering a full GC every hour:
One way is to specify (much) larger values for those properties.
Another way is to launch the JVM with the
-XX:+DisableExplicitGC
flags. Note: this will disable all calls toSystem.gc()
not just the calls that RMI's DGC makes.
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