[infinispan-issues] [JBoss JIRA] (ISPN-6350) Data race in the ShardIndexManager under topology changes

[Gustavo Fernandes (JIRA)]

Gustavo Fernandes created ISPN-6350:
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             Summary: Data race in the ShardIndexManager under topology changes
                 Key: ISPN-6350
                 URL: https://issues.jboss.org/browse/ISPN-6350
             Project: Infinispan
          Issue Type: Bug
            Reporter: Gustavo Fernandes


The following example data race can cause unrecoverable errors during indexing:

\[node1\] cache.put(key)     // key maps to segment 48, owned by node1
\[node1\] starts shard 48
\[node1\] acquires lock on shard 48
\[node1\] starts writing to the index
\[node1\] notification of topology changed, lock released on shard 48
\[node1\] lock reacquired (still writing to the index)   
\[node1\] commit on shard 48
\[node1\] shard still locked
\[node2\] cache.put(key)  // Node2 now owns segment 48
\[node2\] tries to acquire the lock
\[node2\] fail (lock still owned by node1)

The current mechanism employed by the {{ShardIndexManager}} during topology changes involves using a listener and closing the IndexWriter on all nodes upon ownership changes, so that the lock is released and can be reacquired by the new owner (1 segment maps to 1 shard).
Since writing to a shard can take some time, the listener can be triggered in the middle of an index operation and the closing of the index writing will have a very short duration because it is sudden reacquired, and not released again.



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