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ASF GitHub Bot commented on FLINK-4829: --------------------------------------- GitHub user mxm opened a pull request: https://github.com/apache/flink/pull/2634 [FLINK-4829] protect user accumulators against concurrent updates You can merge this pull request into a Git repository by running: $ git pull https://github.com/mxm/flink FLINK-4829 Alternatively you can review and apply these changes as the patch at: https://github.com/apache/flink/pull/2634.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 #2634 ---- commit 922e765f7a8f6870b79c6abb65d6ea681901e80a Author: Maximilian Michels <m...@apache.org> Date: 2016-10-14T13:15:50Z [FLINK-4829] protect user accumulators against concurrent updates ---- > Accumulators are not thread safe > -------------------------------- > > Key: FLINK-4829 > URL: https://issues.apache.org/jira/browse/FLINK-4829 > Project: Flink > Issue Type: Bug > Components: Local Runtime > Affects Versions: 1.2.0 > Reporter: Till Rohrmann > Assignee: Maximilian Michels > Fix For: 1.2.0 > > > Flink's {{Accumulators}} are not thread safe. With the introduction of live > accumulator snapshots which are sent to the {{JobManager}}, we've introduced > a concurrent access to accumulators without properly guard them against > concurrent modifications. So if an accumulator snapshot is taken for an > accumulator which is at the same time modified, it can cause an > {{ConcurrentModificationException}} as it was reported by an user: > {code} > WARN org.apache.flink.runtime.accumulators.AccumulatorRegistry - Failed > to serialize accumulators for task. > java.util.ConcurrentModificationException > at java.util.TreeMap$PrivateEntryIterator.nextEntry(TreeMap.java:1211) > at java.util.TreeMap$EntryIterator.next(TreeMap.java:1247) > at java.util.TreeMap$EntryIterator.next(TreeMap.java:1242) > at java.util.TreeMap.writeObject(TreeMap.java:2436) > at sun.reflect.GeneratedMethodAccessor491.invoke(Unknown Source) > at > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) > at java.lang.reflect.Method.invoke(Method.java:498) > at > java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1028) > 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.writeObject(ObjectOutputStream.java:348) > at java.util.HashMap.internalWriteEntries(HashMap.java:1785) > at java.util.HashMap.writeObject(HashMap.java:1362) > at sun.reflect.GeneratedMethodAccessor189.invoke(Unknown Source) > at > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) > at java.lang.reflect.Method.invoke(Method.java:498) > at > java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1028) > 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.writeObject(ObjectOutputStream.java:348) > at > org.apache.flink.util.InstantiationUtil.serializeObject(InstantiationUtil.java:301) > at > org.apache.flink.util.SerializedValue.<init>(SerializedValue.java:52) > at > org.apache.flink.runtime.accumulators.AccumulatorSnapshot.<init>(AccumulatorSnapshot.java:58) > at > org.apache.flink.runtime.accumulators.AccumulatorRegistry.getSnapshot(AccumulatorRegistry.java:75) > at > org.apache.flink.runtime.taskmanager.TaskManager$$anonfun$sendHeartbeatToJobManager$2.apply(TaskManager.scala:1286) > {code} -- This message was sent by Atlassian JIRA (v6.3.4#6332)