[infinispan-issues] [JBoss JIRA] Updated: (ISPN-799) JoinTask as it invalidates L1 entries should be given precedence in acquiring locks

JoinTask as it invalidates L1 entries should be given precedence in acquiring locks ------------------------------------------------------------------------------------ Key: ISPN-799 URL: https://jira.jboss.org/browse/ISPN-799 Project: Infinispan Issue Type: Bug Components: Locking and Concurrency Affects Versions: 4.2.0.CR2 Reporter: Vladimir Blagojevic Assignee: Vladimir Blagojevic Fix For: 4.2.0.CR4, 4.2.0.Final The SingleJoinTest transaction test failure itself is intermittent due to the way addresses are organised in the hash wheel, so you are correct that it is a timing issue. Anyway, it still is a very real problem. Just to re-iterate and to make sure we are talking about the same thing: 1. View is {A, B, C} 2. K is mapped to {A, B} 3. A tx starts to update K, and is prepared. Locks now held for K on {A, B} 4. D joins. D is placed on the hash wheel between A and B. So the new view is {A, D, B, C} 5. As per the test (artificial, I know, but could still happen), the tx waits for a long time before committing. In the case of the test, artificially waits until D has finished joining before committing, by use of a latch. 6. D never joins as even though it receives the prepare for the tx and could potentially commit itself (as a new owner), it fails as it is unable to invalidate K on B. There are a few solutions here: 1) This is pretty easy to detect. Attempt to acquire the lock with a smaller lock acquisition timeout and if the transaction is still stuck, abort the transaction and proceed with the join. 2) If the blocking node is *not* the transaction originator (as in this case: the tx was started on A), then just force lock removal and tx rollback on B *only*. Let the tx complete on A, since the new joiner will receive the transactional event and will be able to apply it as a new owner. My vote is to go for solution 1 - a bit more crude, but 2 would be very complex to implement. And even then, would only solve for the invalidation being blocked on a node that did not originate the transaction. E.g., the tx originated on A but the lock issue was on B. If, however, the tx originated on B, *and* B no longer owns the entry in question, then 2 is no longer a solution and the only solution would be 1.