Anoop Sam John created HBASE-16162:
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Summary: 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
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.
So all these threads can push the same active to pipeline. We unnecessarily
passing through same segment many times.
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