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From Stefan Richter <s.rich...@data-artisans.com>
Subject Re: FileNotFoundException when restoring checkpoint
Date Mon, 17 Jul 2017 12:37:49 GMT
Hi,

You assumed correctly that savepoints are always self-contained. Are you using externalized
checkpoints? There is a known problem in that was fixed in the latest master and will go into
1.3.2, but this might be a different problem.

You are also correct that incremental checkpoints can reference files from previous checkpoints.
Do you ever manually delete any checkpoint directories? Because they might still be referenced
in other checkpoints.

I would assume that the missing file was written completely, because otherwise the checkpoint
would already fail. However I am unsure about the exact guarantees (e.g. about visibility)
in Azure blobs. Can you check if this file was ever created and when it starts to disappear?
Does the directory of checkpoint 37 still exist in the file system?

Best,
Stefan

> Am 17.07.2017 um 13:12 schrieb Shai Kaplan <Shai.Kaplan@microsoft.com>:
> 
> Hi.
> I'm running Flink 1.3.1 with checkpoints stored in Azure blobs. Incremental checkpoints
feature is on.
> The job is trying to restore a checkpoint and consistently gets:
>  
> java.lang.IllegalStateException: Could not initialize keyed state backend.
>         at org.apache.flink.streaming.api.operators.AbstractStreamOperator.initKeyedState(AbstractStreamOperator.java:321)
>         at org.apache.flink.streaming.api.operators.AbstractStreamOperator.initializeState(AbstractStreamOperator.java:217)
>         at org.apache.flink.streaming.runtime.tasks.StreamTask.initializeOperators(StreamTask.java:676)
>         at org.apache.flink.streaming.runtime.tasks.StreamTask.initializeState(StreamTask.java:663)
>         at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:252)
>         at org.apache.flink.runtime.taskmanager.Task.run(Task.java:702)
>         at java.lang.Thread.run(Thread.java:745)
> Caused by: java.io.FileNotFoundException: wasbs://***/5065c840d4d4ba8c7cd91f793012bab1/chk-37/f52d633b-9d3f-47c1-bf23-58dcc54572e3
<wasbs://***/5065c840d4d4ba8c7cd91f793012bab1/chk-37/f52d633b-9d3f-47c1-bf23-58dcc54572e3>
>         at org.apache.hadoop.fs.azure.NativeAzureFileSystem.open(NativeAzureFileSystem.java:1905)
>         at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:767)
>         at org.apache.flink.runtime.fs.hdfs.HadoopFileSystem.open(HadoopFileSystem.java:404)
>         at org.apache.flink.runtime.fs.hdfs.HadoopFileSystem.open(HadoopFileSystem.java:48)
>         at org.apache.flink.core.fs.SafetyNetWrapperFileSystem.open(SafetyNetWrapperFileSystem.java:85)
>         at org.apache.flink.runtime.state.filesystem.FileStateHandle.openInputStream(FileStateHandle.java:69)
>         at org.apache.flink.contrib.streaming.state.RocksDBKeyedStateBackend$RocksDBIncrementalRestoreOperation.readStateData(RocksDBKeyedStateBackend.java:1276)
>         at org.apache.flink.contrib.streaming.state.RocksDBKeyedStateBackend$RocksDBIncrementalRestoreOperation.readAllStateData(RocksDBKeyedStateBackend.java:1458)
>         at org.apache.flink.contrib.streaming.state.RocksDBKeyedStateBackend$RocksDBIncrementalRestoreOperation.restoreInstance(RocksDBKeyedStateBackend.java:1319)
>         at org.apache.flink.contrib.streaming.state.RocksDBKeyedStateBackend$RocksDBIncrementalRestoreOperation.restore(RocksDBKeyedStateBackend.java:1493)
>         at org.apache.flink.contrib.streaming.state.RocksDBKeyedStateBackend.restore(RocksDBKeyedStateBackend.java:965)
>         at org.apache.flink.streaming.runtime.tasks.StreamTask.createKeyedStateBackend(StreamTask.java:772)
>         at org.apache.flink.streaming.api.operators.AbstractStreamOperator.initKeyedState(AbstractStreamOperator.java:311)
>  
> The name of the missing file is sometimes different, but it's always a missing file in
checkpoint 37. The last successful checkpoint number was 41, so I'm guessing that's the checkpoint
it's trying to restore, but because of the incremental checkpointing it also needs files from
previous checkpoints, which are apparently missing. Could this be a problem in the interface
with Azure? If some files failed to write, why didn't the checkpoint fail?
>  
> When I realized nothing is going to change I canceled the job, and started it from a
savepoint, which was checkpoint number 40. I actually expected it to fail, and that I would
have to restore it from a savepoint prior to the apparently corrupted checkpoint number 37,
but it didn't fail. Should I infer that savepoints are self-contained and are not incremental?


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