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

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).

> > 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>