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https://issues.apache.org/jira/browse/SPARK-22625?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16268483#comment-16268483
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Tolstopyatov Vsevolod commented on SPARK-22625:
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In Spark.
The problem is that thread from third-party library is created after spark
context (thus inheriting its thread local with all the properties, UI object
etc.) and I have no access over this thread (this is library implementation
detail), but it's still spark issue (because spark is the owner of this thread
local): for every inherited thread local spark clones all the properties, so
the they are effectively detached from Spark and close doesn't affect them. And
moreover, this properties are inherited for every thread created after spark
context, so I can't even prevent.
Solution (register every cloned property object and call `.clear` on close for
all of them) will help
> Properly cleanup inheritable thread-locals
> ------------------------------------------
>
> Key: SPARK-22625
> URL: https://issues.apache.org/jira/browse/SPARK-22625
> Project: Spark
> Issue Type: Bug
> Components: Spark Core
> Affects Versions: 2.2.0
> Reporter: Tolstopyatov Vsevolod
> Labels: leak
>
> Memory leak is present due to inherited thread locals, SPARK-20558 didn't
> fixed it properly.
> Our production application has the following logic: one thread is reading
> from HDFS and another one creates spark context, processes HDFS files and
> then closes it on regular schedule.
> Depending on what thread started first, SparkContext thread local may or may
> not be inherited by HDFS-daemon (DataStreamer), causing memory leak when
> streamer was created after spark context. Memory consumption increases every
> time new spark context is created, related yourkit paths:
> https://screencast.com/t/tgFBYMEpW
> The problem is more general and is not related to HDFS in particular.
> Proper fix: register all cloned properties (in `localProperties#childValue`)
> in ConcurrentHashMap and forcefully clear all of them in `SparkContext#close`
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