[infinispan-dev] put if absent not atomic: https://jira.jboss.org/jira/browse/ISPN-236

[Sanne Grinovero]

Hi,
Please note that the tests running in REPL_SYNC mode are not failing
anymore, just DIST is still failing.

I've ported the test to core, as agreed in group "stress" as it's slow
so it's not starting automatically:

mvn test -Dtest=org.infinispan.stress.PutIfAbsentStressTest

Please have a look to the different configurations I've set it to
test; it should be trivial to add more configurations you might want
to check.

thanks for all the support,
Regards,
Sanne

2009/10/23 Mircea Markus <mircea.markus at jboss.com>:
> Hi Manik,
>
> While the fix I made for EntityWrapper fixed the cache in local mode,
> the replicated mode[1] (pretty sure dist is the same) is far from
> working.
> The issue is the following:
> node1.put(k,v2) :: WL(k1) -> releaseLock(k1) -> replicate(k1) ->
> incoming_thread_performs put (k, *v2*)
> node2.put(k,v2) :: WL(k2) -> releaseLock(k2) -> replicate(k2) ->
> incoming_thread_performs put (k, *v1*)
>
> now in this scenario both operation succeed! This is caused by the
> fact that lock interceptor is *after* repl interceptor in the chain,
> so when repl is triggered the key is no longer locked.
> In other words, if the puts happen at the same time, on the same key
> then both might succeed, leaving the cluster in an inconsistent state.
> IMO, the correct approach would be to keep the lock while doing the
> replication. This would reduce the concurrency though, as locks would
> be held for longer amounts of time. But the data consistency would
> increase. (this would be an easy fix for Repl, but dist relies on
> interceptor's order).
>
> I've also tried doing the call within a tx, but there's a deadlock -
> I'll investigate this on Mon.
>
> [1] I know disyt is what we'll use but problem exists for repl as well
>
> Cheers,
> Mircea
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