Re: [infinispan-dev] DeadlockDetection (DLD) - benchmarks and status
On 21 Jul 2009, at 11:19, Mircea Markus wrote:
Hi,
I've extended the original DLD design to also support deadlock
detection on local caches and updated design forum [1].
Does it also support async transports (1-phase commits)?
This, together with the replicated deadlock detection is implemented
in trunk (some minor stuff to do still: DLD for aggregation methods
like clear and addAll + unit test).
I've also created a benchmark to test what's the throughput (tx/min)
between caches running with and without DLD.
You can find full test description within test class:
http://anonsvn.jboss.org/repos/infinispan/trunk/core/src/test/java//org/i...
Local DLD does good job (cca 5.5 times better) but replicated DLD
does extraordinary: cca 101 better throughput (see attached).
This is very interesting, but perhaps a little artificial since your
key pool size is only 10. So you do force a lot of deadlocks as a
result. And the time taken with the non-DLD case would depend on the
TM's transaction timeout configuration which again would vary. So as
a result I'd be careful about quoting performance increase factors in
a public blog (although you should definitely blog about this as a
feature and how it *could* speed up transactions that would otherwise
timeout).
Also, it would be interesting to see how the cache fares with and
without DLD, in a test where there are absolutely no deadlocks. E.g.,
each thread's access patterns access the same keys, but in a way that
would never deadlock. I'd like to see if DLD adds much of an overhead.
Overall though, very cool stuff! :)
Cheers
Manik
I think DLD is cool stuff and differentiates us a bit from
competition, afaik none of them have a DLD.
One more thing that's worth mentioning: while running DLD tests I've
noticed that if all tx acquire locks on keys in same order, then no
deadlocks exists. This is logic and might seem obvious, but is not
stated anywhere and the performance increase by doing this might be
very dramatic. I think we should document this as a best practice
when it comes to transactions - any suggestion where?
I also intend to blog about it shortly.
Cheers,
Mircea
[1] http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4244838#...
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Manik Surtani
manik(a)jboss.org
Lead, Infinispan
Lead, JBoss Cache
http://www.infinispan.org
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