[
https://issues.apache.org/jira/browse/PHOENIX-2970?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
chenglei updated PHOENIX-2970:
------------------------------
Description:
Even if SpoolingResultIterator will be deprecated, but HBase older than
than 0.98.17 would continue use it, and I think the
DeferredByteBufferSegmentQueue class simialr to SpoolingResultIterator in the
future version may also has the same problem.
In SpoolingResultIterator's ctor, it tries to allocate "phoenix.query.
spoolThresholdBytes" bytes from MemoryManager,and uses the allocated
MemoryChunk's size as DeferredFileOutputStream's threshold,just as the
following code:
{code:borderStyle=solid}
final MemoryChunk chunk = mm.allocate(0, thresholdBytes);
long waitTime = System.currentTimeMillis() - startTime;
GLOBAL_MEMORY_WAIT_TIME.update(waitTime);
memoryMetrics.getMemoryWaitTimeMetric().change(waitTime);
DeferredFileOutputStream spoolTo = null;
try {
// Can't be bigger than int, since it's the max of the above
allocation
int size = (int)chunk.getSize();
spoolTo = new DeferredFileOutputStream(size,
"ResultSpooler",".bin", new File(spoolDirectory)) {
@Override
protected void thresholdReached() throws IOException {
try {
super.thresholdReached();
} finally {
chunk.close();
}
}
};
{code}
SpoolingResultIterator assumes that the wrapped ResultIterator would
always fetch "phoenix.query.spoolThresholdBytes" bytes,but most of time it
won't. For example, if we execute "select count(1) from table" on a big table
with many regions, the ScanPlan will parallel too many
SpoolingResultIterators to fetch the result, and each SpoolingResultIterator
tries to allocate "phoenix.query.
spoolThresholdBytes" bytes from MemoryManager.If we don't have too many memory,
lots of SpoolingResultIterators will allocate 0 bytes from MemoryManager,and
the DeferredFileOutputStream will unnecessaryly use temp file to put the
results, even if the result is just a single count value. This behavior will
slow the query.
Can we remove the MemoryManager,just as the MappedByteBufferSortedQueue
does?
was:
Even if SpoolingResultIterator will be deprecated, but HBase older than
than 0.98.17 would continue use it, and I think the
DeferredByteBufferSegmentQueue class simialr to SpoolingResultIterator in the
future version may also has the same problem.
In SpoolingResultIterator's ctor, it tries to allocate "phoenix.query.
spoolThresholdBytes" bytes from MemoryManager,and uses the allocated
MemoryChunk's size as DeferredFileOutputStream's threshold,just as the
following code:
{code:borderStyle=solid}
final MemoryChunk chunk = mm.allocate(0, thresholdBytes);
long waitTime = System.currentTimeMillis() - startTime;
GLOBAL_MEMORY_WAIT_TIME.update(waitTime);
memoryMetrics.getMemoryWaitTimeMetric().change(waitTime);
DeferredFileOutputStream spoolTo = null;
try {
// Can't be bigger than int, since it's the max of the above
allocation
int size = (int)chunk.getSize();
spoolTo = new DeferredFileOutputStream(size,
"ResultSpooler",".bin", new File(spoolDirectory)) {
@Override
protected void thresholdReached() throws IOException {
try {
super.thresholdReached();
} finally {
chunk.close();
}
}
};
{code}
SpoolingResultIterator assumes that the wrapped ResultIterator would
always fetch "phoenix.query.spoolThresholdBytes" bytes,but most of time it
won't. For example, if we execute "select count(*) from table" on a big table
with many regions, the ScanPlan will parallel too many
SpoolingResultIterators to fetch the result, and each SpoolingResultIterator
tries to allocate "phoenix.query.
spoolThresholdBytes" bytes from MemoryManager.If we don't have too many memory,
lots of SpoolingResultIterators will allocate 0 bytes from MemoryManager,and
the DeferredFileOutputStream will unnecessaryly use temp file to put the
results, even if the result is just a single count value. This behavior will
slow the query.
Can we remove the MemoryManager,just as the MappedByteBufferSortedQueue
does?
> SpoolingResultIterator using memory too conservative
> -----------------------------------------------------
>
> Key: PHOENIX-2970
> URL: https://issues.apache.org/jira/browse/PHOENIX-2970
> Project: Phoenix
> Issue Type: Bug
> Affects Versions: 4.7.0
> Reporter: chenglei
>
> Even if SpoolingResultIterator will be deprecated, but HBase older than
> than 0.98.17 would continue use it, and I think the
> DeferredByteBufferSegmentQueue class simialr to SpoolingResultIterator in
> the future version may also has the same problem.
> In SpoolingResultIterator's ctor, it tries to allocate "phoenix.query.
> spoolThresholdBytes" bytes from MemoryManager,and uses the allocated
> MemoryChunk's size as DeferredFileOutputStream's threshold,just as the
> following code:
> {code:borderStyle=solid}
> final MemoryChunk chunk = mm.allocate(0, thresholdBytes);
> long waitTime = System.currentTimeMillis() - startTime;
> GLOBAL_MEMORY_WAIT_TIME.update(waitTime);
> memoryMetrics.getMemoryWaitTimeMetric().change(waitTime);
> DeferredFileOutputStream spoolTo = null;
> try {
> // Can't be bigger than int, since it's the max of the above
> allocation
> int size = (int)chunk.getSize();
> spoolTo = new DeferredFileOutputStream(size,
> "ResultSpooler",".bin", new File(spoolDirectory)) {
> @Override
> protected void thresholdReached() throws IOException {
> try {
> super.thresholdReached();
> } finally {
> chunk.close();
> }
> }
> };
> {code}
>
> SpoolingResultIterator assumes that the wrapped ResultIterator would
> always fetch "phoenix.query.spoolThresholdBytes" bytes,but most of time it
> won't. For example, if we execute "select count(1) from table" on a big table
> with many regions, the ScanPlan will parallel too many
> SpoolingResultIterators to fetch the result, and each SpoolingResultIterator
> tries to allocate "phoenix.query.
> spoolThresholdBytes" bytes from MemoryManager.If we don't have too many
> memory, lots of SpoolingResultIterators will allocate 0 bytes from
> MemoryManager,and the DeferredFileOutputStream will unnecessaryly use temp
> file to put the results, even if the result is just a single count value.
> This behavior will slow the query.
> Can we remove the MemoryManager,just as the MappedByteBufferSortedQueue
> does?
>
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