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https://issues.apache.org/jira/browse/HBASE-16162?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Anoop Sam John updated HBASE-16162:
-----------------------------------
Priority: Critical (was: Major)
> Unnecessary push active segments to pipeline
> --------------------------------------------
>
> Key: HBASE-16162
> URL: https://issues.apache.org/jira/browse/HBASE-16162
> Project: HBase
> Issue Type: Sub-task
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Priority: Critical
>
> We have flow like this
> {code}
> protected void checkActiveSize() {
> if (shouldFlushInMemory()) {
> InMemoryFlushRunnable runnable = new InMemoryFlushRunnable();
> }
> getPool().execute(runnable);
> }
> }
> private boolean shouldFlushInMemory() {
> if(getActive().getSize() > inmemoryFlushSize) {
> // size above flush threshold
> return (allowCompaction.get() && !inMemoryFlushInProgress.get());
> }
> return false;
> }
> void flushInMemory() throws IOException {
> // Phase I: Update the pipeline
> getRegionServices().blockUpdates();
> try {
> MutableSegment active = getActive();
> pushActiveToPipeline(active);
> } finally {
> getRegionServices().unblockUpdates();
> }
> // Phase II: Compact the pipeline
> try {
> if (allowCompaction.get() &&
> inMemoryFlushInProgress.compareAndSet(false, true)) {
> // setting the inMemoryFlushInProgress flag again for the case this
> method is invoked
> // directly (only in tests) in the common path setting from true to
> true is idempotent
> // Speculative compaction execution, may be interrupted if flush is
> forced while
> // compaction is in progress
> compactor.startCompaction();
> }
> {code}
> So every write of cell will produce the check checkActiveSize(). When we
> are at border of in mem flush, many threads doing writes to this memstore
> can get this check to pass. Yes the AtomicBoolean is still false only. It is
> turned ON after some time once the new thread is started run and it push the
> active to pipeline etc.
> The time gap btw the size check return true and the block updates. In btw
> all updates to memstore would have kicked this in memory flush
> So all these threads can push the same active to pipeline. We unnecessarily
> passing through same segment many times.
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