[jira] [Created] (IGNITE-1159) Redundant MVCC queue iteration may be removed

["Alexey Goncharuk (JIRA)" <ji...@apache.org>]

Alexey Goncharuk created IGNITE-1159:
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             Summary: Redundant MVCC queue iteration may be removed
                 Key: IGNITE-1159
                 URL: https://issues.apache.org/jira/browse/IGNITE-1159
             Project: Ignite
          Issue Type: Bug
          Components: cache
    Affects Versions: sprint-7
            Reporter: Alexey Goncharuk
            Assignee: Alexey Goncharuk
             Fix For: sprint-8


When MVCC lock candidates are added for multiple keys, they are linked together to ensure proper lock acquisition order. The linkage is done in GridCacheMvccManager#addNext()
The manager contains a thread-local queue of previously added candidates which is reset after each message. When a candidate is added, addNext() iterates over the queue and unlinks used candidates.

The drawback of this code is that on large batches of size N (say, a batch of 100 values) the code will execute N^2 operations which dramatically reduces performance of bulk transactions.

It looks like that this code is unnecessary because:
1) Candidates cannot become used while lock request being processed.
2) There is no need to unlink as the candidates will be GCed after locks are released.



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