[SPARK-21243][Core] Limit no. of map outputs in a shuffle fetch #18691
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For configurations with external shuffle enabled, we have observed that if a very large no. of blocks are being fetched from a remote host, it puts the NM under extra pressure and can crash it. This change introduces a configuration
spark.reducer.maxBlocksInFlightPerAddress, to limit the no. of map outputs being fetched from a given remote address. The changes applied here are applicable for both the scenarios - when external shuffle is enabled as well as disabled.Ran the job with the default configuration which does not change the existing behavior and ran it with few configurations of lower values -10,20,50,100. The job ran fine and there is no change in the output. (I will update the metrics related to NM in some time.)
Author: Dhruve Ashar [email protected]
Closes #18487 from dhruve/impr/SPARK-21243.