[infinispan-dev] CHM or CHMv8?

[Dan Berindei]

+1 to make CHMv8 the default on JDK6 and JDK7

But I'm not convinced we should make it the default for JDK8 - even though
we don't know exactly what we're getting with the JDK's implementation.


On Fri, Apr 19, 2013 at 5:39 AM, David M. Lloyd <david.lloyd at redhat.com>wrote:

> On 04/18/2013 09:35 PM, Manik Surtani wrote:
> > Guys,
> >
> > Based on some recent micro benchmarks I've been doing, I've seen:
> >
> > MapStressTest configuration: capacity 100000, test running time 60
> seconds
> > Testing mixed read/write performance with capacity 100,000, keys
> 300,000, concurrency level 32, threads 12, read:write ratio 0:1
> > Container CHM           Ops/s 21,165,771.67  Gets/s       0.00  Puts/s
> 21,165,771.67  HitRatio     100.00  Size    262,682  stdDev 77,540.73
> > Container CHMV8         Ops/s 33,513,807.09  Gets/s       0.00  Puts/s
> 33,513,807.09  HitRatio     100.00  Size    262,682  stdDev 77,540.73
> >
> > So under high concurrency (12 threads, on my workstation with 12
> hardware threads - so all threads are always working), we see that
> Infinispan's CHMv8 implementation is 50% faster than JDK6's CHM
> implementation when doing puts.
> >
> > We use a fair number of CHMs all over Infinispan's codebase.  By
> default, these are all JDK-provided CHMs.  But we have the option to switch
> to our CHMv8 implementation by passing in
> -Dinfinispan.unsafe.allow_jdk8_chm=true.
> >
> > The question is, should this be the default?  Thoughts, opinions?
>
> The JDK's concurrency code - especially CHM - changes all the time.
> You'd be very well-served, in my opinion, to go with something like
> CHMv8 just because you could be so much more sure that you'll have more
> consistent (and possibly better, but definitely more consistent)
> performance across all JVMs, instead of being at the mercy of whatever
> particular implementation happens to run on whatever JVM.
>
>
> --
> - DML
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