Contribution: Lock Contention Profiler for HotSpot

Andrew Dinn adinn at
Fri Nov 4 14:21:31 UTC 2016

On 04/11/16 12:04, Peter Hofer wrote:
   . . .
>> Have you measured the overhead this change produces when running with
>> contention detection disabled? (i.e. do we pay to have this feature even
>> when we don't use it).
> We measured only the overhead relative to an unmodified OpenJDK build.
> Our profiler observes only lock contention, which is generally handled
> via slow paths in the VM code, so this is where we added the code to
> record events. I don't expect this code to cause much overhead when
> disabled. However, we added fields to several data structures, which
> might make a difference.

Yes, increased footprint (in code as well as object space) would be as
much a concern as increased execution time.

> I'll run some more benchmarks and report my findings.

Thanks very much.


Andrew Dinn
Senior Principal Software Engineer
Red Hat UK Ltd
Registered in England and Wales under Company Registration No. 03798903
Directors: Michael Cunningham, Michael ("Mike") O'Neill, Eric Shander

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