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[SPARK-21474][CORE] Make number of parallel fetches from a reducer configurable - #18683
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raajay wants to merge 2 commits into
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[SPARK-21474][CORE] Make number of parallel fetches from a reducer configurable#18683raajay wants to merge 2 commits into
raajay wants to merge 2 commits into
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AmplabJenkins
commented
Jul 19, 2017
Can one of the admins verify this patch? |
jiangxb1987
commented
Jul 20, 2017
Contributor
I'm not convinced we need this configuration, we can always control the size of each fetch request by |
Author
maxSizeInFlight can be large (~100-200 MB) when (a) available memory at reducer is high, or (b) when reducer spends most of its time waiting for fetchRequests. In such cases, using a hard coded value of '5' parallel fetches will result in individual fetchRequests to be bursts of size 20-40 MB. The configuration parameter, allows one to have smaller sized fetchRequests while keeping the total maxSizeInFlight a constant. |
jerryshao
commented
Jul 20, 2017
Contributor
Did you see an explicit performance change while changing this parameter? I would think netty client thread number for shuffle is still a bottleneck even if you split into more fetch requests. We already have bunch of configurations to control the request size, memory usage, bytes in flight here in shuffle fetch, adding more configuration really complex the logics. |
zifeif2 pushed a commit
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Nov 22, 2025
## What changes were proposed in this pull request? This PR proposes to close stale PRs, mostly the same instances with apache#18017Closesapache#14085 - [SPARK-16408][SQL] SparkSQL Added file get Exception: is a directory … Closesapache#14239 - [SPARK-16593] [CORE] [WIP] Provide a pre-fetch mechanism to accelerate shuffle stage. Closesapache#14567 - [SPARK-16992][PYSPARK] Python Pep8 formatting and import reorganisation Closesapache#14579 - [SPARK-16921][PYSPARK] RDD/DataFrame persist()/cache() should return Python context managers Closesapache#14601 - [SPARK-13979][Core] Killed executor is re spawned without AWS key… Closesapache#14830 - [SPARK-16992][PYSPARK][DOCS] import sort and autopep8 on Pyspark examples Closesapache#14963 - [SPARK-16992][PYSPARK] Virtualenv for Pylint and pep8 in lint-python Closesapache#15227 - [SPARK-17655][SQL]Remove unused variables declarations and definations in a WholeStageCodeGened stage Closesapache#15240 - [SPARK-17556] [CORE] [SQL] Executor side broadcast for broadcast joins Closesapache#15405 - [SPARK-15917][CORE] Added support for number of executors in Standalone [WIP] Closesapache#16099 - [SPARK-18665][SQL] set statement state to "ERROR" after user cancel job Closesapache#16445 - [SPARK-19043][SQL]Make SparkSQLSessionManager more configurable Closesapache#16618 - [SPARK-14409][ML][WIP] Add RankingEvaluator Closesapache#16766 - [SPARK-19426][SQL] Custom coalesce for Dataset Closesapache#16832 - [SPARK-19490][SQL] ignore case sensitivity when filtering hive partition columns Closesapache#17052 - [SPARK-19690][SS] Join a streaming DataFrame with a batch DataFrame which has an aggregation may not work Closesapache#17267 - [SPARK-19926][PYSPARK] Make pyspark exception more user-friendly Closesapache#17371 - [SPARK-19903][PYSPARK][SS] window operator miss the `watermark` metadata of time column Closesapache#17401 - [SPARK-18364][YARN] Expose metrics for YarnShuffleService Closesapache#17519 - [SPARK-15352][Doc] follow-up: add configuration docs for topology-aware block replication Closesapache#17530 - [SPARK-5158] Access kerberized HDFS from Spark standalone Closesapache#17854 - [SPARK-20564][Deploy] Reduce massive executor failures when executor count is large (>2000) Closesapache#17979 - [SPARK-19320][MESOS][WIP]allow specifying a hard limit on number of gpus required in each spark executor when running on mesos Closesapache#18127 - [SPARK-6628][SQL][Branch-2.1] Fix ClassCastException when executing sql statement 'insert into' on hbase table Closesapache#18236 - [SPARK-21015] Check field name is not null and empty in GenericRowWit… Closesapache#18269 - [SPARK-21056][SQL] Use at most one spark job to list files in InMemoryFileIndex Closesapache#18328 - [SPARK-21121][SQL] Support changing storage level via the spark.sql.inMemoryColumnarStorage.level variable Closesapache#18354 - [SPARK-18016][SQL][CATALYST][BRANCH-2.1] Code Generation: Constant Pool Limit - Class Splitting Closesapache#18383 - [SPARK-21167][SS] Set kafka clientId while fetch messages Closesapache#18414 - [SPARK-21169] [core] Make sure to update application status to RUNNING if executors are accepted and RUNNING after recovery Closesapache#18432 - resolve com.esotericsoftware.kryo.KryoException Closesapache#18490 - [SPARK-21269][Core][WIP] Fix FetchFailedException when enable maxReqSizeShuffleToMem and KryoSerializer Closesapache#18585 - SPARK-21359 Closesapache#18609 - Spark SQL merge small files to big files Update InsertIntoHiveTable.scala Added: Closesapache#18308 - [SPARK-21099][Spark Core] INFO Log Message Using Incorrect Executor I… Closesapache#18599 - [SPARK-21372] spark writes one log file even I set the number of spark_rotate_log to 0 Closesapache#18619 - [SPARK-21397][BUILD]Maven shade plugin adding dependency-reduced-pom.xml to … Closesapache#18667 - Fix the simpleString used in error messages Closesapache#18782 - Branch 2.1 Added: Closesapache#17694 - [SPARK-12717][PYSPARK] Resolving race condition with pyspark broadcasts when using multiple threads Added: Closesapache#16456 - [SPARK-18994] clean up the local directories for application in future by annother thread Closesapache#18683 - [SPARK-21474][CORE] Make number of parallel fetches from a reducer configurable Closesapache#18690 - [SPARK-21334][CORE] Add metrics reporting service to External Shuffle Server Added: Closesapache#18827 - Merge pull request 1 from apache/master ## How was this patch tested? N/A Author: hyukjinkwon <gurwls223@gmail.com> Closesapache#18780 from HyukjinKwon/close-prs.
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What changes were proposed in this pull request?
Currently the number of parallel fetches is hard-coded to 5. As a result the size of each fetch request is fixed at 1/5th of maxSizeInFlights. Since, chunks are requested in bursts of fetchRequests; the size of a burst to a single shuffle service can be high for large maxSizeInFlight
Introduce a new configuration parameter "spark.reducer.numParallelFetchRequets" to make it configurable.
How was this patch tested?
Not tested.