Very long safepoint pauses for RevokeBias

[Christopher Berner]

Don't think it got truncated, but I only included the first line of log
about the safepoint statistics. Turning off biased locks seem to have fixed
those pauses, thanks!

Just to help me understand, what circumstances would cause biased locking
to induce 28sec pauses? Is that because a thread was holding the lock for
28sec?

On Sun, May 17, 2015 at 1:54 PM, David Holmes <david.holmes at oracle.com>
wrote:

> Hi Christopher,
>
>
> On 16/05/2015 10:38 AM, Christopher Berner wrote:
>
>> I work on the Presto project, which is a distributed SQL engine, and
>> intermittently (roughly once an hour) I see very long application stopped
>> times (as reported by
>>     -XX:+PrintGCApplicationStoppedTime). I enabled safepoint statistics,
>> and
>> see that the pause seems to be coming from a RevokeBias safepoint.
>>
>> Any suggestions as to how I can debug this? I already tried adding
>> -XX:+PerfDisableSharedMem, in case this was related to
>> https://bugs.openjdk.java.net/browse/JDK-8076103
>>
>> See below for safepoint statistics:
>>
>>           vmop                    [threads: total initially_running
>> wait_to_block]    [time: spin block sync cleanup vmop] page_trap_count
>>
>> 2528.893: RevokeBias                       [     872          0
>>    6    ]      [     0 12826 13142  6476  8177    ]  0
>>
>
> Your email seems to be truncated?
>
> But just to be sure, does the application run okay with biased-locking
> disabled?
>
> David
>
>