Yu Li created HBASE-17747:
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Summary: Support both weak and soft object pool
Key: HBASE-17747
URL: https://issues.apache.org/jira/browse/HBASE-17747
Project: HBase
Issue Type: Improvement
Reporter: Yu Li
Assignee: Yu Li
During YCSB testing on embedded mode after HBASE-17744, we found that under
high read load GC is quite severe even with offheap L2 cache. After some
investigation, we found it's caused by using weak reference for
IdReadWriteLock. In embedded mode the read is so quick that the lock might
already get promoted to the old generation when the weak reference is cleared,
which causes dirty card table thus slowing YGC.
So we proposed to use soft reference for this IdReadWriteLock used in cache,
which won't get cleared until JVM memory is not enough, and could resolve the
issue mentioned above. What's more, we propose to extend the WeakObjectPool to
be more generate to support both weak and soft reference.
Note that this issue only emerges under embedded mode with DirectOperator, in
which case all costs on the wire is removed thus produces extremely high
workloads.
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