[infinispan-dev] deadlock detection - coin toss

[Mircea Markus]

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