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ramkrishna.s.vasudevan updated HBASE-11126: ------------------------------------------- Status: Open (was: Patch Available) > Add RegionObserver pre hooks that operate under row lock > -------------------------------------------------------- > > Key: HBASE-11126 > URL: https://issues.apache.org/jira/browse/HBASE-11126 > Project: HBase > Issue Type: Improvement > Affects Versions: 0.98.3, 0.99.0 > Reporter: Andrew Purtell > Assignee: ramkrishna.s.vasudevan > Attachments: HBASE-11126_1.patch, HBASE-11126_new_2.patch, > HBASE-11126_new_3.patch > > > The coprocessor hooks were placed outside of row locks. This was meant to > sidestep performance issues arising from significant work done within hook > invocations. However as the security code increases in sophistication we are > now running into concurrency issues trying to use them as a result of that > early decision. Since the initial introduction of coprocessor upcalls there > has been some significant refactoring done around them and concurrency > control in core has become more complex. This is potentially an issue for > many coprocessor users. > We should do either:\\ > - Move all existing RegionObserver pre* hooks to execute under row lock. > - Introduce a new set of RegionObserver pre* hooks that execute under row > lock, named to indicate such. > The second option is less likely to lead to surprises. > All RegionObserver hook Javadoc should be updated with advice to the > coprocessor implementor not to take their own row locks in the hook. If the > current thread happens to already have a row lock and they try to take a lock > on another row, there is a deadlock risk. > As always a drawback of adding hooks is the potential for performance impact. > We should benchmark the impact and decide if the second option above is a > viable choice or if the first option is required. > Finally, we should introduce a higher level interface for managing the > registration of 'user' code for execution from the low level hooks. I filed > HBASE-11125 to discuss this further. -- This message was sent by Atlassian JIRA (v6.2#6252)