Alexey Scherbakov created IGNITE-20895:
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             Summary: Optimize hierarchy lock manager
                 Key: IGNITE-20895
                 URL: https://issues.apache.org/jira/browse/IGNITE-20895
             Project: Ignite
          Issue Type: Improvement
    Affects Versions: 3.0
            Reporter: Alexey Scherbakov
             Fix For: 3.0


Recently a (not very efficient) parentLockManager  [1]was introduced to handle 
hierarchy (coarse-grained) locks.

Currently it's only purpose is to provide strict serializability during full 
table scans, which happed very rarely.

It comes at the cost of acquiring additional lock on each update op. IS locks 
are never used at all.

It should be improved. Possible optimizations:
 # Get rid of hierarchy locks and instead scan the primary index for table 
scane.
 # Replace lock queuing for IS,IX locks with counters. This prevents waiting, 
but is looks ok for this kind of locks. Only stronger locks should be allowed 
to wait.

[1] org.apache.ignite.internal.tx.impl.HeapLockManager#parentLockManager



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