[jira] [Assigned] (TEZ-4075) Tez: Reimplement tez.runtime.transfer.data-via-events.enabled

["Richard Zhang (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TEZ-4075?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Richard Zhang reassigned TEZ-4075:
----------------------------------

    Assignee: Richard Zhang

> Tez: Reimplement tez.runtime.transfer.data-via-events.enabled
> -------------------------------------------------------------
>
>                 Key: TEZ-4075
>                 URL: https://issues.apache.org/jira/browse/TEZ-4075
>             Project: Apache Tez
>          Issue Type: Bug
>            Reporter: Gopal V
>            Assignee: Richard Zhang
>            Priority: Major
>         Attachments: Tez-4075.3.patch
>
>
> This was factored out by TEZ-2196, which does skip buffers for 1-partition data exchanges (therefore goes to disk directly).
> {code}
>     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);	
>     }	
> {code}
> 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.



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