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TEZ-4407: Misleading split info in TezSplitGrouper logs when adjusting small splits #202

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Merged
abstractdog merged 4 commits into from
Dec 23, 2024
+14 −22
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TEZ-4407: Misleading split info in TezSplitGrouper logs when adjusting small splits #202

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b9033f8
TEZ-4407: Misleading split info in TezSplitGrouper logs when adjustin…
zabetak Apr 20, 2022
c715c0b
Clarify what happens when all spits are in localhost with log message
zabetak Jun 26, 2023
8f7797a
Group log messages and always print when bounds exceeded
zabetak Jun 26, 2023
d0384d4
Always print new desired splits even if not changed.
zabetak Jun 26, 2023
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17 changes: 7 additions & 10 deletions tez-mapreduce/src/main/java/org/apache/tez/mapreduce/grouper/TezSplitGrouper.java
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Original file line number Diff line number Diff line change
Expand Up @@ -260,23 +260,20 @@ public List<GroupedSplitContainer> getGroupedSplits(Configuration conf,
desiredNumSplits = newDesiredNumSplits;
} else if (lengthPerGroup < minLengthPerGroup) {
// splits too small to work. Need to override with size.
int newDesiredNumSplits = (int)(totalLength/minLengthPerGroup) + 1;
/**
* This is a workaround for systems like S3 that pass the same
* fake hostname for all splits.
*/
if (!allSplitsHaveLocalhost) {
int newDesiredNumSplits = (int)(totalLength/minLengthPerGroup) + 1;
LOG.info("Desired splits: " + desiredNumSplits + " too large. " +
" Desired splitLength: " + lengthPerGroup +
" Min splitLength: " + minLengthPerGroup +
" New desired splits: " + newDesiredNumSplits +
" Total length: " + totalLength +
" Original splits: " + originalSplits.size());
desiredNumSplits = newDesiredNumSplits;
}
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@abstractdog abstractdog Jun 24, 2023

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what about adding an else branch here with some useful log message describing whatever happens (or doesn't happen) when allSplitsHaveLocalhost=true
otherwise LGTM
cc: @rbalamohan

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@zabetak zabetak Jun 26, 2023

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I added a log message here c715c0b and also made a small refactoring to gather logging in one place and always log if splitLength bounds are exceeded.

Anyways the most important point in this patch is to be able to see the original desiredNumSplits in every case; especially when it is different from newDesiredNumSplits or not.


LOG.info("Desired splits: " + desiredNumSplits + " too large. " +
" Desired splitLength: " + lengthPerGroup +
" Min splitLength: " + minLengthPerGroup +
" New desired splits: " + newDesiredNumSplits +
" Final desired splits: " + desiredNumSplits +
" All splits have localhost: " + allSplitsHaveLocalhost +
" Total length: " + totalLength +
" Original splits: " + originalSplits.size());
}
}

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