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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-10060) Unsynchronized scanning
Date Sun, 01 Dec 2013 00:57:35 GMT
Lars Hofhansl created HBASE-10060:
-------------------------------------

             Summary: Unsynchronized scanning
                 Key: HBASE-10060
                 URL: https://issues.apache.org/jira/browse/HBASE-10060
             Project: HBase
          Issue Type: Bug
            Reporter: Lars Hofhansl


HBASE-10015 has some lengthy discussion. The solution there ended up replacing synchronized
with ReentrantLock, which - somewhat surprisingly - yielded a non-trivial improvement for
tall tables.
The goal should be to avoid locking in StoreScanner at all. StoreScanner is only accessed
by a single thread *except* when we have a concurrent flush or a compaction, which is rare
(we'd acquire and release the lock millions of times per second, and compact/flush a few time
an hour at the most).




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