RFR: 8204554: JFR TLAB tracing broken after 8202776

Erik Österlund erik.osterlund at oracle.com
Mon Jun 11 10:19:06 UTC 2018

Hi Thomas,

Thanks for the review.


On 2018-06-11 11:34, Thomas Schatzl wrote:
> Hi,
> On Thu, 2018-06-07 at 16:27 +0200, Erik Österlund wrote:
>> Hi,
>> The recent allocation path modularization (8202776) broke JFR TLAB
>> sampling. This was discovered in tier 5 testing.
>> The problem is that there was previously an early exit TLAB path,
>> that should not run the tracing code when not returning NULL, and a
>> mem_allocate call that should run the tracing code when not
>> returning NULL. However, these paths were joined in a virtual member
>> function, making them look the same to the tracing code, which caused
>> the non-TLAB tracing code to be run on TLAB allocations as well.
>> The solution I propose is to move the TLAB tracing code into the new
>> virtual member function. It seems that whatever GC overrides this
>> code, should also decide what to do about the tracing code there
>> anyway.
>    looks good.
> Thomas

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