RFR: 8012241 NMT huge memory footprint, it usually leads to OOME

[Karen Kinnear]

Zhengyu,

Looks good for 7u40 and 8.

And thank you Christian for so much testing.

Many thanks,
Karen

On Jul 11, 2013, at 9:07 AM, Zhengyu Gu wrote:

> The patch is a workaround that prevents JVM from OOM when running Kitchensink with NMT on some slow machines.
> 
> Kitchensink normally runs with about 100 threads, peaks around 150 threads. On some slow machines, NMT worker thread does not process raw NMT data quick enough, that causes huge backlogs, which consumes large amount of memory and can lead JVM OOM. By enforcing the new threshold, NMT will shutdown itself and free NMT memory.
> 
> If native memory tracking is important to diagnostic memory issue, user can use -XX:-AutoShutdownNMT diagnostic flag to override above behavior. Turning off auto shutdown NMT flag, NMT also tries slow down malloc/free rate, to give NMT worker thread a chance to catch up.
> 
> 
> JBS: https://jbs.oracle.com/bugs/browse/JDK-8012241
> Exteneral bug: not available
> Webrev: http://cr.openjdk.java.net/~zgu/8012241/webrev.00/ <http://cr.openjdk.java.net/%7Ezgu/8012241/webrev.00/>
> 
> 
> Tests:
>  Christian Tornqvist has verified on Windows and Solaris, that patch prevented JVM from OOM.
> 
> Thanks,
> 
> -Zhengyu