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https://issues.apache.org/jira/browse/SPARK-1630?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14077945#comment-14077945
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Josh Rosen commented on SPARK-1630:
-----------------------------------
Hi Kalpit,
Thanks for sharing your use-case; it seems like a reasonable thing that we
should support.
As part of [~mlnick]'s patch for [SPARK-1416], we now have
{{SerDeUtil.rddToPython}} for converting pair RDDs of arbitrary Java objects
into RDDs that can be read by PySpark. One alternative to this fix proposed
here would be to add a similar converter from non-pair-RDDs to PythonRDDs that
used the Java-side pickle library to pickle the strings as nulls. However,
this could have a negative performance impact since we'd be passing pickled
objects instead of UTF-8 strings.
Given that the current proposed fix only affects RDD<String> and seems unlikely
to mask serious bugs, I'm inclined to merge it.
> PythonRDDs don't handle nulls gracefully
> ----------------------------------------
>
> Key: SPARK-1630
> URL: https://issues.apache.org/jira/browse/SPARK-1630
> Project: Spark
> Issue Type: Bug
> Components: PySpark, SQL
> Affects Versions: 0.9.0, 0.9.1
> Reporter: Kalpit Shah
> Assignee: Davies Liu
> Original Estimate: 2h
> Remaining Estimate: 2h
>
> If PythonRDDs receive a null element in iterators, they currently NPE. It
> would be better do log a DEBUG message and skip the write of NULL elements.
> Here are the 2 stack traces :
> 14/04/22 03:44:19 ERROR executor.Executor: Uncaught exception in thread
> Thread[stdin writer for python,5,main]
> java.lang.NullPointerException
> at
> org.apache.spark.api.python.PythonRDD$.writeIteratorToStream(PythonRDD.scala:267)
> at org.apache.spark.api.python.PythonRDD$$anon$2.run(PythonRDD.scala:88)
> -------------------------------------------------------------------------------------
> Py4JJavaError: An error occurred while calling
> z:org.apache.spark.api.python.PythonRDD.writeToFile.
> : java.lang.NullPointerException
> at org.apache.spark.api.python.PythonRDD$.writeUTF(PythonRDD.scala:273)
> at
> org.apache.spark.api.python.PythonRDD$$anonfun$writeIteratorToStream$2.apply(PythonRDD.scala:247)
> at
> org.apache.spark.api.python.PythonRDD$$anonfun$writeIteratorToStream$2.apply(PythonRDD.scala:246)
> at scala.collection.Iterator$class.foreach(Iterator.scala:727)
> at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
> at
> org.apache.spark.api.python.PythonRDD$.writeIteratorToStream(PythonRDD.scala:246)
> at org.apache.spark.api.python.PythonRDD$.writeToFile(PythonRDD.scala:285)
> at org.apache.spark.api.python.PythonRDD$.writeToFile(PythonRDD.scala:280)
> at org.apache.spark.api.python.PythonRDD.writeToFile(PythonRDD.scala)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:606)
> at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:231)
> at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:379)
> at py4j.Gateway.invoke(Gateway.java:259)
> at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
> at py4j.commands.CallCommand.execute(CallCommand.java:79)
> at py4j.GatewayConnection.run(GatewayConnection.java:207)
> at java.lang.Thread.run(Thread.java:744)
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