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https://issues.apache.org/jira/browse/HBASE-17361?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15772018#comment-15772018
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Duo Zhang commented on HBASE-17361:
-----------------------------------
I think HTable is known to be not thread safe from long long ago?
> HTable#getBufferedMutator is not thread safe and could cause data loss
> ----------------------------------------------------------------------
>
> Key: HBASE-17361
> URL: https://issues.apache.org/jira/browse/HBASE-17361
> Project: HBase
> Issue Type: Bug
> Affects Versions: 1.1.7, 1.2.4
> Reporter: Yu Li
> Assignee: Yu Li
> Priority: Critical
> Attachments: HBASE-17361.patch, HBASE-17361.patch
>
>
> 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}
> Will add a UT to cover this case, and fix it in this JIRA.
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