Re: [infinispan-dev] DeadlockDetection (DLD) - benchmarks and status

On 23 Jul 2009, at 16:51, Mircea Markus wrote: > Manik Surtani wrote: >> >> 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)? > I've just finished implementing 1PC. >> >>> 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. > I've also run such a test (is the same test as previously, but the > key set is ordered now -> no deadlocks). The average performance > decrease is approx 7%. (See attached). Any idea where the overhead is? Have you run this through a profiler?

>> >> 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#... >>> >>> >>> >>> <DLD_local.JPG><DLD_replicated.JPG>_______________________________________________ >>> >>> infinispan-dev mailing list >>> infinispan-dev(a)lists.jboss.org >>> https://lists.jboss.org/mailman/listinfo/infinispan-dev >> >> -- >> Manik Surtani >> manik(a)jboss.org >> Lead, Infinispan >> Lead, JBoss Cache >> http://www.infinispan.org >> http://www.jbosscache.org >> >> >> >> > > <DLD_enabling_overhead.JPG> -- Manik Surtani manik(a)jboss.org Lead, Infinispan Lead, JBoss Cache http://www.infinispan.org http://www.jbosscache.org