RFR (S): 8023461: Thread holding lock at safepoint that vm can block on: MethodCompileQueue_lock

[Vladimir Ivanov]

Igor, Vladimir, thanks for review.

Best regards,
Vladimir Ivanov

On 3/11/14 7:31 AM, Igor Veresov wrote:
> I think it’s a reasonable fix.
>
> igor
>
> On Mar 10, 2014, at 4:57 PM, Vladimir Ivanov <vladimir.x.ivanov at oracle.com> wrote:
>
>> Vladimir, thanks for the review.
>>
>> You are absolutely right about Method::increment_interpreter_invocation_count. Reverted the change.
>>
>> Updated fix:
>> http://cr.openjdk.java.net/~vlivanov/8023461/webrev.01/
>>
>> Yes, Igor's feedback on this change would be invaluable.
>>
>> Best regards,
>> Vladimir Ivanov
>>
>> On 3/11/14 2:33 AM, Vladimir Kozlov wrote:
>>> The method Method::increment_interpreter_invocation_count(TRAP) changes
>>> are incorrect. It is used by C++ Interpreter and you did not modified
>>> code there. I would leave this method unchanged.
>>>
>>> The rest looks fine to me but Igor should know better this code.
>>>
>>> Thanks,
>>> Vladimir K
>>>
>>> On 3/7/14 8:26 AM, Vladimir Ivanov wrote:
>>>> http://cr.openjdk.java.net/~vlivanov/8023461/webrev.00
>>>> https://bugs.openjdk.java.net/browse/JDK-8023461
>>>> 42 lines changed: 13 ins; 1 del; 28 mod
>>>>
>>>> The rule of thumb for VM is that a thread shouldn't hold any VM lock
>>>> when it reaches a safepoint. It's not the case for
>>>> MethodCompileQueue_lock now.
>>>>
>>>> The problem is that AdvancedThresholdPolicy updates task's rate when
>>>> iterating compiler queue. It holds MethodCompileQueue_lock while doing
>>>> so. Method counters are allocated lazily. If method counters aren't
>>>> there and VM fails to allocate them, GC is initiated (see
>>>> CollectorPolicy::satisfy_failed_metadata_allocation) and a thead
>>>> entering a safepoint holding MethodCompileQueue lock.
>>>>
>>>> Normally, counters are initialized during method interpretation, but in
>>>> Xcomp mode it's not the case. That's the mode where the failures are
>>>> observed.
>>>>
>>>> The fix is to skip the update, if counters aren't allocated yet.
>>>>
>>>> Testing: added No_Safepoint_Verifier, JPRT, failing tests from nightly
>>>> testing (in progress).
>>>>
>>>> Best regards,
>>>> Vladimir Ivanov
>