Re: [infinispan-dev] deadlock detection - coin toss

Random is definitely thread-safe in the Sun derived JVMs, and probably thread-safe in other JVMs. I would just use that. Otherwise you could implement MT: http://en.wikipedia.org/wiki/Mersenne_twister Mircea Markus wrote: > this is regarding: http://tinyurl.com/nunmyu > In order to be able to determine which tx should commit and which will > rollback, I need to generate a coin toss for each node - a random number. > In order to do that I'm thinking to use on of the following: > > 1) use java.util.Random . The issue with this class is that it has an > undocumented behavior when it comes to concurrent access, so I cannot > rely on it behaving correctly if I don't enforce proper > synchronization. I'm afraid this might become a bottleneck as all the > prepapares requests might want to synchronize on it. > 2) Another approach would be to build an Random instance for each > call. I made a test an the performance cost of new Random() + > Random.nextLong is about 4 times bigger than call of random.nextLong > only (on my laptop only), still about 15 mils for 1k creations > 3) use System.nanos. Even though the conflicting tx are created at the > same time, the chance for it to happen in the same nanosecond is very > small, I would say. Don't know how this works for all architectures, > though... > > Any feedback much welcomed! > > Cheers, > Mircea > > _______________________________________________ > infinispan-dev mailing list > infinispan-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/infinispan-dev