[infinispan-dev] ISPN-777 and dealing with stale locks

Mircea Markus mircea.markus at jboss.com
Mon Dec 6 09:25:20 EST 2010

Thanks for the fix mate!
On 3 Dec 2010, at 14:58, Manik Surtani wrote:

> Mircea's initial fix [1] for ISPN-777 was on the right track but incomplete, as witnessed by comments here [2]:
> I've made a few more changes [3] to this which will now be in 4.2.0.CR3.  Anyway, the purpose of this email is to summarise my changes:
> * Transactions self-destructing was only present on LockingInterceptor.visitLockControlCommand() [4].  This should also be on visiting prepare commands since this is the other place that locks can be acquired and a remote node disappearing.
> * The check above is still not enough.  There is a race between conducting the check on a transaction and actually acquiring a lock.  E.g., a remote transaction may seem valid in [4] but by the time the thread acquires the lock, the node could have died rendering its transaction stale.  For this purpose, I have added a validity field to RemoteTransaction [5] which is flagged whenever a RollbackCommand is invoked [6] [7].  This allows the stale transaction cleanup task to flag such transactions as invalid even if they are being processed on the fly.  Finally, I have a check for this flag whenever locks are acquired and entries written to [8] and appropriate lock release if this is the case [9].
> * I've also added a stress test that demonstrates this problem better (much more repeatable), based on the original test submitted by the reporter.
> * Some other minor tweaks like better logging and toString() impls.  :-)
> Cheers
> Manik
> [1] https://github.com/infinispan/infinispan/commit/51257cb
> [2] http://community.jboss.org/thread/158844?tstart=0
> [3] https://github.com/infinispan/infinispan/commit/ca0b28f314bb0a59edc0dfa7453f66fcd9162b26
> [4] https://github.com/infinispan/infinispan/commit/51257cb#L1R148
> [5] https://github.com/infinispan/infinispan/commit/ca0b28f314bb0a59edc0dfa7453f66fcd9162b26#L8R34
> [6] https://github.com/infinispan/infinispan/commit/ca0b28f314bb0a59edc0dfa7453f66fcd9162b26#L4R56
> [7] https://github.com/infinispan/infinispan/commit/ca0b28f314bb0a59edc0dfa7453f66fcd9162b26#L1R83
> [9] https://github.com/infinispan/infinispan/commit/ca0b28f314bb0a59edc0dfa7453f66fcd9162b26#L8R74
> [10] https://github.com/infinispan/infinispan/commit/ca0b28f314bb0a59edc0dfa7453f66fcd9162b26#diff-11
> --
> Manik Surtani
> manik at jboss.org
> Lead, Infinispan
> Lead, JBoss Cache
> http://www.infinispan.org
> http://www.jbosscache.org
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