Rob Dawson created SPARK-26183:
----------------------------------
Summary: ConcurrentModificationException when using Spark
collectionAccumulator
Key: SPARK-26183
URL: https://issues.apache.org/jira/browse/SPARK-26183
Project: Spark
Issue Type: Bug
Components: Spark Core
Affects Versions: 2.3.1
Reporter: Rob Dawson
I'm trying to run a Spark-based application on an Azure HDInsight on-demand
cluster, and am seeing lots of SparkExceptions (caused by
ConcurrentModificationExceptions) being logged. The application runs without
these errors when I start a local Spark instance.
I've seen reports of [similar errors when using
accumulators|https://issues.apache.org/jira/browse/SPARK-17463] and my code is
indeed using a CollectionAccumulator, however I have placed synchronized blocks
everywhere I use it, and it makes no difference. The accumulator code looks
like this:
{code:scala}
class MySparkClass(sc : SparkContext) {
val myAccumulator = sc.collectionAccumulator[MyRecord]
override def add(record: MyRecord) = {
synchronized {
myAccumulator.add(record)
}
}
override def endOfBatch() = {
synchronized {
myAccumulator.value.asScala.foreach((record: MyRecord) => {
processIt(record)
})
}
}
}{code}
The exceptions don't cause the application to fail, however when the code tries
to read values out of the accumulator it is empty and {{processIt}} is never
called.
{code}
18/11/26 11:04:37 WARN Executor: Issue communicating with driver in heartbeater
org.apache.spark.SparkException: Exception thrown in awaitResult:
at org.apache.spark.util.ThreadUtils$.awaitResult(ThreadUtils.scala:205)
at org.apache.spark.rpc.RpcTimeout.awaitResult(RpcTimeout.scala:75)
at org.apache.spark.rpc.RpcEndpointRef.askSync(RpcEndpointRef.scala:92)
at
org.apache.spark.executor.Executor.org$apache$spark$executor$Executor$$reportHeartBeat(Executor.scala:785)
at
org.apache.spark.executor.Executor$$anon$2$$anonfun$run$1.apply$mcV$sp(Executor.scala:814)
at
org.apache.spark.executor.Executor$$anon$2$$anonfun$run$1.apply(Executor.scala:814)
at
org.apache.spark.executor.Executor$$anon$2$$anonfun$run$1.apply(Executor.scala:814)
at org.apache.spark.util.Utils$.logUncaughtExceptions(Utils.scala:1988)
at org.apache.spark.executor.Executor$$anon$2.run(Executor.scala:814)
at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.util.ConcurrentModificationException
at java.util.ArrayList.writeObject(ArrayList.java:770)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at
java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1140)
at
java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at
java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at
java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at
java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:441)
at
java.util.Collections$SynchronizedCollection.writeObject(Collections.java:2081)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at
java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1140)
at
java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at
java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at
java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at
java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at
java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
at
java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at
java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at
java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at
java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at
java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at
java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
at
java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at
java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at
java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at
org.apache.spark.serializer.JavaSerializationStream.writeObject(JavaSerializer.scala:43)
at
org.apache.spark.rpc.netty.RequestMessage.serialize(NettyRpcEnv.scala:565)
at org.apache.spark.rpc.netty.NettyRpcEnv.ask(NettyRpcEnv.scala:231)
at
org.apache.spark.rpc.netty.NettyRpcEndpointRef.ask(NettyRpcEnv.scala:523)
at org.apache.spark.rpc.RpcEndpointRef.askSync(RpcEndpointRef.scala:91)
... 13 more
{code}
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