Details
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Improvement
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Status: Resolved
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Major
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Resolution: Fixed
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None
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None
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None
Description
This was factored out by TEZ-2196, which does skip buffers for 1-partition data exchanges (therefore goes to disk directly).
if (shufflePayload.hasData()) { shuffleManager.addKnownInput(shufflePayload.getHost(),
DataProto dataProto = shufflePayload.getData(); shufflePayload.getPort(), srcAttemptIdentifier, srcIndex);
FetchedInput fetchedInput = inputAllocator.allocate(dataProto.getRawLength(),
dataProto.getCompressedLength(), srcAttemptIdentifier);
moveDataToFetchedInput(dataProto, fetchedInput, hostIdentifier);
shuffleManager.addCompletedInputWithData(srcAttemptIdentifier, fetchedInput);
} else {
shuffleManager.addKnownInput(shufflePayload.getHost(),
shufflePayload.getPort(), srcAttemptIdentifier, srcIndex);
}
got removed in
https://github.com/apache/tez/commit/1ba1f927c16a1d7c273b6cd1a8553e5269d1541a
It would be better to buffer up the 512Byte limit for the event size before writing to disk, since creating a new file always incurs disk traffic, even if the file is eventually being served out of the buffer cache.
The total overhead of receiving an event, then firing an HTTP call to fetch the data etc adds approx 100-150ms to a query - the data xfer through the event will skip the disk entirely for this & also remove the extra IOPS incurred.
This channel is not suitable for large-scale event transport, but specifically the workload here deals with 1-row control tables which consume more bandwidth with HTTP headers and hostnames than the 93 byte payload.
