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https://issues.apache.org/jira/browse/SPARK-34573?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Takeshi Yamamuro updated SPARK-34573:
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Affects Version/s: 3.1.2
3.2.0
> SQLConf sqlConfEntries map has a global lock, should not lock on get
> --------------------------------------------------------------------
>
> Key: SPARK-34573
> URL: https://issues.apache.org/jira/browse/SPARK-34573
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 2.4.7, 3.0.2, 3.2.0, 3.1.2
> Reporter: Gabriele Nizzoli
> Priority: Major
>
> SQLConf object has a sqlConfEntries map, which has a global lock (since it
> implements a Collections.synchronizedMap).
> Every operation (like get or set) blocks the full object.
> Concurrent threads may wait on lock.
> An example is the DatatType.sameType method, that queries SQLConf entries map:
> {code:scala}
> if (SQLConf.get.caseSensitiveAnalysis)
> ...
> {code}
> If this data type check is run in a custom piece of code on an executor with
> multiple cores (eg: 40), then a lot of time will be lost waiting on the lock.
> An easy fix is to use the a ConcurrentHashMap that does not lock on read
> SQLConf.get): " ... retrieval operations do not entail locking ..."
> NOTE: originally discovered by Benson Hon <benso...@taboola.com> at Taboola
> while debugging strange slowdowns in production code
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