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https://issues.apache.org/jira/browse/HBASE-17361?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15825775#comment-15825775
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Duo Zhang commented on HBASE-17361:
-----------------------------------
I suggest that we introduce TableBuilder for both 2.0 and 1.x. We can deprecate
the setters in 1.x and remove them 2.0. This means in 1.x, HTable is thread
safe only if you do not call these methods.
Is this acceptable?
> 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.
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