RFR: 8057037: Verification in ClassLoaderData::is_alive is too slow

Volker Simonis volker.simonis at gmail.com
Wed Apr 8 12:45:50 UTC 2015


Hi Stefan,

have you considered downporting this to 8u-dev?
I would do it myself, but unfortunately it is in shared code so I
would need a sponsor anyway.

This hurts us badly especially on our slow porting platforms where we
get GC-times of several minutes now.

Thank you and best regards,
Volker

On Tue, Sep 2, 2014 at 3:03 PM, Stefan Karlsson
<stefan.karlsson at oracle.com> wrote:
> Hi all,
>
> Please review this patch to remove some verification code that was added
> during the G1 Class Unloading project. The code was added to make sure we
> catch any class unloading bugs as early as possible. This verification code
> is run too often and is causing large GC times in our fastdebug test runs.
> In one of the tests I investigated, the Full GCs take 8 seconds with this
> verification and 0.2 seconds without it. Most of the verified pointers are
> already verified before and after GCs in ClassLoaderDataGraph::verify().
>
> http://cr.openjdk.java.net/~stefank/8057037/webrev.00/
>
> thanks,
> StefanK


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