GitHub user BryanCutler opened a pull request:
https://github.com/apache/spark/pull/18695
[SPARK-12717][PYTHON] Adding thread-safe broadcast pickle registry
## What changes were proposed in this pull request?
When using PySpark broadcast variables in a multi-threaded environment,
`SparkContext._pickled_broadcast_vars` becomes a shared resource. A race
condition can occur when broadcast variables that are pickled from one thread
get added to the shared ` _pickled_broadcast_vars` and become part of the
python command from another thread. This PR introduces a thread-safe pickled
registry where the lock can be acquired while the python command is pickled
(causing the broadcast variable to be pickled and added to the registry) and
all pickled broadcast variables for that command can be retrieved.
## How was this patch tested?
Existing unit tests.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/BryanCutler/spark
pyspark-bcast-threadsafe-SPARK-12717
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/18695.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 #18695
----
commit b703f8359cee3c65018fe43f45e26c50771866c7
Author: Bryan Cutler <[email protected]>
Date: 2017-07-20T21:36:09Z
Added thread-safe broadcast pickle registry
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