RFR: 8204554: JFR TLAB tracing broken after 8202776

Roman Kennke rkennke at redhat.com
Thu Jun 7 15:11:21 UTC 2018

Looks good. Go!


> Hi Roman,
> Thanks for the review.
> StefanK thought it would be nicer to move the outside of TLAB path into
> a new function. So I did that. Hope you agree that is a good idea. If
> you want to override that behaviour you can still override
> obj_allocate_raw.
> Full webrev:
> cr.openjdk.java.net/~eosterlund/8204554/webrev.01/
> Incremental webrev:
> cr.openjdk.java.net/~eosterlund/8204554/webrev.00_01/
> Checked again that tests pass now, and it passes.
> Thanks,
> /Erik
> On 2018-06-07 16:41, Roman Kennke wrote:
>> Hi Erik,
>>> 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.
>>> Webrev:
>>> http://cr.openjdk.java.net/~eosterlund/8204554/webrev.00/
>>> Bug:
>>> https://bugs.openjdk.java.net/browse/JDK-8204554
>>> I have run failing tests locally to verify they have been fixed with the
>>> proposed patch. I am now running hs-tier1-3 as well, but am waiting for
>>> the results.
>> This looks good to me. Thank you!
>> Roman

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