Andrew Ash created SPARK-21563:
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Summary: Race condition when serializing TaskDescriptions and
adding jars
Key: SPARK-21563
URL: https://issues.apache.org/jira/browse/SPARK-21563
Project: Spark
Issue Type: Bug
Components: Spark Core
Affects Versions: 2.2.0
Reporter: Andrew Ash
cc [~robert3005]
I was seeing this exception during some running Spark jobs:
{noformat}
16:16:28.294 [dispatcher-event-loop-14] ERROR org.apache.spark.rpc.netty.Inbox
- Ignoring error
java.io.EOFException: null
at java.io.DataInputStream.readFully(DataInputStream.java:197)
at java.io.DataInputStream.readUTF(DataInputStream.java:609)
at java.io.DataInputStream.readUTF(DataInputStream.java:564)
at
org.apache.spark.scheduler.TaskDescription$$anonfun$decode$1.apply(TaskDescription.scala:127)
at
org.apache.spark.scheduler.TaskDescription$$anonfun$decode$1.apply(TaskDescription.scala:126)
at scala.collection.immutable.Range.foreach(Range.scala:160)
at
org.apache.spark.scheduler.TaskDescription$.decode(TaskDescription.scala:126)
at
org.apache.spark.executor.CoarseGrainedExecutorBackend$$anonfun$receive$1.applyOrElse(CoarseGrainedExecutorBackend.scala:95)
at
org.apache.spark.rpc.netty.Inbox$$anonfun$process$1.apply$mcV$sp(Inbox.scala:117)
at org.apache.spark.rpc.netty.Inbox.safelyCall(Inbox.scala:205)
at org.apache.spark.rpc.netty.Inbox.process(Inbox.scala:101)
at
org.apache.spark.rpc.netty.Dispatcher$MessageLoop.run(Dispatcher.scala:213)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:748)
{noformat}
After some debugging, we determined that this is due to a race condition in
task serde introduced in SPARK-19796. cc [~irashid] [~kayousterhout]
The race is between adding additional jars to the SparkContext and serializing
the TaskDescription.
Consider this sequence of events:
- TaskSetManager creates a TaskDescription using a reference to the
SparkContext's jars:
https://github.com/apache/spark/blob/v2.2.0/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala#L506
- TaskDescription starts serializing, and begins writing jars:
https://github.com/apache/spark/blob/v2.2.0/core/src/main/scala/org/apache/spark/scheduler/TaskDescription.scala#L84
- the size of the jar map is written out:
https://github.com/apache/spark/blob/v2.2.0/core/src/main/scala/org/apache/spark/scheduler/TaskDescription.scala#L63
- _on another thread_: the application adds a jar to the SparkContext's jars
list
- then the entries in the jars list are serialized out:
https://github.com/apache/spark/blob/v2.2.0/core/src/main/scala/org/apache/spark/scheduler/TaskDescription.scala#L64
The problem now is that the jars list is serialized as having N entries, but
actually N+1 entries follow that count!
This causes task deserialization to fail in the executor, with the stacktrace
above.
The same issue also likely exists for files, though I haven't observed that and
our application does not stress that codepath the same way it did for jar
additions.
One fix here is that TaskSetManager could make an immutable copy of the jars
list that it passes into the TaskDescription constructor, so that list doesn't
change mid-serialization.
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