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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