]
Dan Berindei commented on ISPN-5046:
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If A and B crashed, C and D will stay in degraded mode until the administrator will change
the cache availability to Available manually. When that happens, C can decide that the
transaction was not committed anywhere else and roll back T.
C should only give up when the cache is Available again. Of course, it wouldn't be a
good idea to keep a thread blocked for all that time, but I think it's reasonable to
block other transactions from updating the same keys.
A cache won't suddenly become available because another node joined: availability can
only be restored when merging with other nodes from the latest stable cache topology (or
when the admin intervenes manually).
PartitionHandling: split during commit can leave the cache
inconsistent after merge
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Key: ISPN-5046
URL:
https://issues.jboss.org/browse/ISPN-5046
Project: Infinispan
Issue Type: Bug
Components: Core, State Transfer
Affects Versions: 7.0.2.Final, 7.1.0.Alpha1
Reporter: Dan Berindei
Priority: Critical
Fix For: 7.1.0.Beta1
Say we have a cluster ABCD; a transaction T was started on A, with B as the primary owner
and C the backup owner. B and C both acknowledge the prepare, and the network splits into
AB and CD right before A sends the commit command. Eventually A suspects C and D, but the
commit still succeeds on B before C and D are suspected. And SuspectExceptions are ignored
for commit commands, so the user won't see any error.
However, C will eventually suspect A and B. When the CD cache topology is installed, it
will roll back transaction T. After the merge, both partitions are in degraded mode, so we
assume that they both have the latest data and the key is never updated on C.
From C's point of view, this is very similar to ISPN-3421. The fix should also be
similar, we could delay the transaction rollback on C until we get a confirmation from B
that T was not committed there. Since B is inaccessible, it will eventually get a
SuspectException and the CD cache topology, at which point the cache is in degraded mode
and it can wait for a merge. On merge, it should check the status of the transaction on B
again, and either commit or rollback based on what B did.
We also need to suspend the cleanup of completed transactions while the cache is in
degraded mode, otherwise C might not find T on B after the merge.