GitHub user vundela opened a pull request:
https://github.com/apache/spark/pull/17694
[SPARK-12717][PYSPARK] Resolving race condition with pyspark broadcasâ¦
â¦ts when using multiple threads
## What changes were proposed in this pull request?
In pyspark when multiple threads are used, broadcast variables are picked
with wrong PythonRDD wrap functions which leads to the following
exception(Because of the race condition between the threads on java side with
py4j).
16/01/08 17:10:20 ERROR Executor: Exception in task 0.0 in stage 9.0 (TID 9)
org.apache.spark.api.python.PythonException: Traceback (most recent call
last):
File
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/worker.py",
line 98, in main
command = pickleSer._read_with_length(infile)
File
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/serializers.py",
line 164, in _read_with_length
return self.loads(obj)
File
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/serializers.py",
line 422, in loads
return pickle.loads(obj)
File
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/broadcast.py",
line 39, in _from_id
raise Exception("Broadcast variable '%s' not loaded!" % bid)
Exception: (Exception("Broadcast variable '6' not loaded!",), , (6L,))
at
org.apache.spark.api.python.PythonRunner$$anon$1.read(PythonRDD.scala:166)
at
org.apache.spark.api.python.PythonRunner$$anon$1.(PythonRDD.scala:207)
at org.apache.spark.api.python.PythonRunner.compute(PythonRDD.scala:125)
at org.apache.spark.api.python.PythonRDD.compute(PythonRDD.scala:70)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:306)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:270)
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:66)
at org.apache.spark.scheduler.Task.run(Task.scala:89)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:213)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
This change will fix the race condition by making sure that broadcast
variables are picked with same pythonRDD function.
## How was this patch tested?
1) Reproduced the issue mentioned in SPARK-12717, following the
instructions specified in jira
2) Make sure that issue is fixed with the changes.
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/vundela/spark SPARK-12717
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/17694.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 #17694
commit 4670678ba4fa7f2a7f66bc9309716fcefb05c54d
Author: Srinivasa Reddy Vundela
Date: 2017-04-20T01:37:12Z
[SPARK-12717][PYSPARK] Resolving race condition with pyspark broadcasts
when using multiple threads
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