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https://issues.apache.org/jira/browse/FLINK-12653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16849943#comment-16849943
]
Maximilian Michels commented on FLINK-12653:
--------------------------------------------
Some more information, these are the involved Beam serializers:
{noformat}
VarIntCoder,
KvCoder(org.apache.beam.sdk.coders.SerializableCoder,org.apache.beam.sdk.coders.AvroCoder),
WindowedValue$FullWindowedValueCoder(KvCoder(StringUtf8Coder,VarLongCoder),GlobalWindow$Coder),
TimerInternals$TimerDataCoder(GlobalWindow$Coder),
FlinkKeyUtils$ByteBufferCoder]
{noformat}
> Keyed state backend fails to restore during rescaling
> -----------------------------------------------------
>
> Key: FLINK-12653
> URL: https://issues.apache.org/jira/browse/FLINK-12653
> Project: Flink
> Issue Type: Bug
> Components: Runtime / State Backends
> Affects Versions: 1.6.4, 1.7.2, 1.8.0
> Environment: Beam 2.12.0 or any other Beam version
> Flink >= 1.6
> Heap/Filesystem state backend (RocksDB works fine)
> Reporter: Maximilian Michels
> Priority: Critical
>
> The Flink Runner includes a test which verifies checkpoints/savepoints work
> correctly with Beam on Flink. When adding additional tests for
> scaleup/scaledown [1], I came across a bug with restoring the keyed state
> backend. After a fair amount of debugging Beam code and checking any
> potential issues with serializers, I think this could be a Flink issue.
> Steps to reproduce:
> 1. {{git clone https://github.com/mxm/beam}}
> 2. {{cd beam && git checkout savepoint-problem}}
> 3. {{./gradlew :runners:flink:1.6:test --tests
> "**.FlinkSavepointTest.testSavepointRestoreLegacy"}}
> Error:
> {noformat}
> java.lang.Exception: Exception while creating StreamOperatorStateContext.
> at
> org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.streamOperatorStateContext(StreamTaskStateInitializerImpl.java:192)
> at
> org.apache.flink.streaming.api.operators.AbstractStreamOperator.initializeState(AbstractStreamOperator.java:250)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.initializeState(StreamTask.java:738)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:289)
> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:711)
> at java.lang.Thread.run(Thread.java:745)
> Caused by: org.apache.flink.util.FlinkException: Could not restore keyed
> state backend for DoFnOperator_76375152c4a81d5df72cf49e32c4ecb9_(4/4) from
> any of the 1 provided restore options.
> at
> org.apache.flink.streaming.api.operators.BackendRestorerProcedure.createAndRestore(BackendRestorerProcedure.java:137)
> at
> org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.keyedStatedBackend(StreamTaskStateInitializerImpl.java:279)
> at
> org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.streamOperatorStateContext(StreamTaskStateInitializerImpl.java:133)
> ... 5 more
> Caused by: java.lang.RuntimeException: Invalid namespace string: ''
> at
> org.apache.beam.runners.core.StateNamespaces.fromString(StateNamespaces.java:245)
> at
> org.apache.beam.runners.core.TimerInternals$TimerDataCoder.decode(TimerInternals.java:246)
> at
> org.apache.beam.runners.core.TimerInternals$TimerDataCoder.decode(TimerInternals.java:221)
> at
> org.apache.beam.runners.flink.translation.types.CoderTypeSerializer.deserialize(CoderTypeSerializer.java:92)
> at
> org.apache.flink.streaming.api.operators.TimerSerializer.deserialize(TimerSerializer.java:169)
> at
> org.apache.flink.streaming.api.operators.TimerSerializer.deserialize(TimerSerializer.java:45)
> at
> org.apache.flink.runtime.state.KeyGroupPartitioner$PartitioningResultKeyGroupReader.readMappingsInKeyGroup(KeyGroupPartitioner.java:297)
> at
> org.apache.flink.runtime.state.heap.HeapKeyedStateBackend.readKeyGroupStateData(HeapKeyedStateBackend.java:513)
> at
> org.apache.flink.runtime.state.heap.HeapKeyedStateBackend.readStateHandleStateData(HeapKeyedStateBackend.java:474)
> at
> org.apache.flink.runtime.state.heap.HeapKeyedStateBackend.restorePartitionedState(HeapKeyedStateBackend.java:431)
> at
> org.apache.flink.runtime.state.heap.HeapKeyedStateBackend.restore(HeapKeyedStateBackend.java:370)
> at
> org.apache.flink.runtime.state.heap.HeapKeyedStateBackend.restore(HeapKeyedStateBackend.java:105)
> at
> org.apache.flink.streaming.api.operators.BackendRestorerProcedure.attemptCreateAndRestore(BackendRestorerProcedure.java:151)
> at
> org.apache.flink.streaming.api.operators.BackendRestorerProcedure.createAndRestore(BackendRestorerProcedure.java:123)
> ... 7 more
> {noformat}
> It is possible to change the {{maxParallelism}} to other values. The
> following lead to failure:
> {noformat}
> options.setMaxParallelism(128); // default value
> options.setMaxParallelism(64);
> options.setMaxParallelism(118);
> {noformat}
> The following work fine:
> {noformat}
> options.setMaxParallelism(110);
> options.setMaxParallelism(63);
> options.setMaxParallelism(24);
> {noformat}
> [1]
> https://github.com/apache/beam/commit/52d7291144f64eaa417862558d71a443fae3d690
> Everything works fine with RocksDB.
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