GitHub user dhruve opened a pull request:
https://github.com/apache/spark/pull/18691
[SPARK-21243][Core] Limit no. of map outputs in a shuffle fetch
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.
## What changes were proposed in this pull request?
(Please fill in changes proposed in this fix)
## How was this patch tested?
(Please explain how this patch was tested. E.g. unit tests, integration
tests, manual tests)
(If this patch involves UI changes, please attach a screenshot; otherwise,
remove this)
Please review http://spark.apache.org/contributing.html before opening a
pull request.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/dhruve/spark branch-2.2
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/18691.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #18691
----
commit 036eb17d32c1b9b0f76ab9c0c4a10f6248728476
Author: Dhruve Ashar <[email protected]>
Date: 2017-07-19T20:53:28Z
[SPARK-21243][Core] Limit no. of map outputs in a shuffle fetch
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.
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