Review Request (7u): JDK-8048271: Minor GC times doubled from JDK 6u35 to JDK 7u51

Kirk Pepperdine kirk at kodewerk.com
Mon Jul 14 06:50:15 UTC 2014


Hi Poonam,

Do you know if roots formally in perm were preventing a lot of data from being reclaimed by the minor collections?

Regards,
Kirk

On Jul 14, 2014, at 2:47 AM, Poonam Bajaj <poonam.bajaj at oracle.com> wrote:

> Bug: JDK-8048271: Minor GC times doubled from JDK 6u35 to JDK 7u51 
> Webrev: http://cr.openjdk.java.net/~poonam/8048271/webrev.00/
> 
> With JDK7, the minor GC collection times have increased as compared to the collection times with JDK6uxx. These pauses have increased due to the fact that the Intern strings and the class statics were moved from PermGen to the Java Heap in JDK7 and, are collected as part of the minor GC collections thus contributing to the increase in GC times.
> 
> These changes make the debug flag 'JavaObjectsInPerm' a diagnostic flag so that it can be used to revert the PermGen changes in jdk7 and get the earlier minor GC pause times.
> 
> Testing:
> Manual testing comparing the PSYoungGen times with and without JavaObjectsInPerm option
> JPRT
> 
> 
> Thanks,
> Poonam
> 
> 

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