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

Jon Masamitsu jon.masamitsu at oracle.com
Wed Jul 16 13:36:33 UTC 2014




-------- Original Message --------
Subject: 	Re: Review Request (7u): JDK-8048271: Minor GC times doubled 
from JDK 6u35 to JDK 7u51
Date: 	Tue, 15 Jul 2014 09:18:31 -0700
From: 	Jon Masamitsu <jon.masamitsu at oracle.com>
To: 	Poonam Bajaj <poonam.bajaj at oracle.com>




Poonam,

Code change looks fine.

Reviewed.

If possible the customer should test with jdk8 since this
workaround will not help with jdk8.  That will just let us
know how bad the problem is in jdk8.

Jon

On 07/13/2014 05:47 PM, Poonam Bajaj wrote:
> Bug: JDK-8048271 <https://bugs.openjdk.java.net/browse/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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