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Yu Li resolved HBASE-17361. --------------------------- Resolution: Fixed Resolving issue since all sub tasks closed. > Make HTable thread safe > ----------------------- > > Key: HBASE-17361 > URL: https://issues.apache.org/jira/browse/HBASE-17361 > Project: HBase > Issue Type: Improvement > Reporter: Yu Li > Assignee: Yu Li > Priority: Critical > Attachments: HBASE-17361.patch, HBASE-17361.patch > > > Currently HTable is marked as NOT thread safe, and this JIRA target at > improving this to take better usage of the thread-safe BufferedMutator. > Some findings/work done: > If we try to do put to the same HTable instance in parallel, there'll be > problem, since now we have {{HTable#getBufferedMutator}} like > {code} > BufferedMutator getBufferedMutator() throws IOException { > if (mutator == null) { > this.mutator = (BufferedMutatorImpl) connection.getBufferedMutator( > new BufferedMutatorParams(tableName) > .pool(pool) > .writeBufferSize(connConfiguration.getWriteBufferSize()) > .maxKeyValueSize(connConfiguration.getMaxKeyValueSize()) > ); > } > mutator.setRpcTimeout(writeRpcTimeout); > mutator.setOperationTimeout(operationTimeout); > return mutator; > } > {code} > And {{HTable#flushCommits}}: > {code} > void flushCommits() throws IOException { > if (mutator == null) { > // nothing to flush if there's no mutator; don't bother creating one. > return; > } > getBufferedMutator().flush(); > } > {code} > For {{HTable#put}} > {code} > public void put(final Put put) throws IOException { > getBufferedMutator().mutate(put); > flushCommits(); > } > {code} > If we launch multiple threads to put in parallel, below sequence might happen > because {{HTable#getBufferedMutator}} is not thread safe: > {noformat} > 1. ThreadA runs to getBufferedMutator and finds mutator==null > 2. ThreadB runs to getBufferedMutator and finds mutator==null > 3. ThreadA initialize mutator to instanceA, then calls mutator#mutate, > adding one put (putA) into {{writeAsyncBuffer}} > 4. ThreadB initialize mutator to instanceB > 5. ThreadA runs to flushCommits, now mutator is instanceB, it calls > instanceB's flush method, putA is lost > {noformat} > After fixing this, we will find quite some contention on > {{BufferedMutatorImpl#flush}}, so more efforts required to make HTable thread > safe but with good performance meanwhile. -- This message was sent by Atlassian JIRA (v6.4.14#64029)