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From "Tzu-Li (Gordon) Tai (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-5849) Kafka Consumer checkpointed state may contain undefined offsets
Date Mon, 20 Feb 2017 15:42:44 GMT

    [ https://issues.apache.org/jira/browse/FLINK-5849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15874714#comment-15874714
] 

Tzu-Li (Gordon) Tai commented on FLINK-5849:
--------------------------------------------

Some background context on the problem:
In FLINK-4280, the logic that fetcher's run at the start of {{runFetchLoop()}} was changed
to:
{code}
if (isRestored) {
    // just use the offsets in the restored state as starting position
} else {
    // find out the starting offsets based on StartupMode (either EARLIEST, LATEST, or GROUP_OFFSETS),
    // and set the partition states with the discovered start offsets so that the state has
defined offsets
}
{code}

So, the change also assumed that on restore, the state should not have undefined offsets.
As pointed out in the description of this JIRA, this is not true if a checkpoint was taken
before {{runFetchLoop()}} was reached.

The approaches I see in fixing this:
1. The faster fix - also let the {{if (isRestored)}} branch handle states that don't have
defined offsets.
2. Rework the life cycle of {{AbstractFetcher}}. We should instantiate {{AbstractFetcher}}
in the {{open()}} method of the UDF, and let the startup offset determining process happen
in the constructor of {{AbstractFetcher}}. This assures that there will always be defined
offsets when checkpointing happens.

Option (2) will be more work, but I prefer that over (1) because it seems to be a more proper
fix.
Option (1) will lead to more complicated start position determining logic, since for partition
states with undefined offsets, we need to "fallback" to the {{StartupMode}} for that partition.
This will be a problem for the {{LATEST}} startup mode - we would be using the latest record
*at the time the job was restored with that undefined offset*, and not correctly at the time
of the actual first execution of the job.

> Kafka Consumer checkpointed state may contain undefined offsets
> ---------------------------------------------------------------
>
>                 Key: FLINK-5849
>                 URL: https://issues.apache.org/jira/browse/FLINK-5849
>             Project: Flink
>          Issue Type: Bug
>          Components: Kafka Connector
>            Reporter: Tzu-Li (Gordon) Tai
>            Assignee: Tzu-Li (Gordon) Tai
>            Priority: Critical
>
> This is a regression due to FLINK-4280.
> In FLINK-4280, all initial offset determination was refactored to be consolidated at
the start of {{AbstractFetcher#runFetchLoop}}. However, this caused checkpoints that were
triggered before the method was ever reached to contain undefined partition offsets.
> Ref:
> {code}
> org.apache.flink.client.program.ProgramInvocationException: The program execution failed:
Job execution failed.
>     at org.apache.flink.client.program.ClusterClient.run(ClusterClient.java:427)
>     at org.apache.flink.client.program.StandaloneClusterClient.submitJob(StandaloneClusterClient.java:101)
>     at org.apache.flink.client.program.ClusterClient.run(ClusterClient.java:400)
>     at org.apache.flink.client.program.ClusterClient.run(ClusterClient.java:392)
>     at org.apache.flink.streaming.api.environment.RemoteStreamEnvironment.executeRemotely(RemoteStreamEnvironment.java:209)
>     at org.apache.flink.streaming.api.environment.RemoteStreamEnvironment.execute(RemoteStreamEnvironment.java:173)
>     at org.apache.flink.test.util.TestUtils.tryExecute(TestUtils.java:32)
>     at org.apache.flink.streaming.connectors.kafka.KafkaConsumerTestBase.runMultipleSourcesOnePartitionExactlyOnceTest(KafkaConsumerTestBase.java:942)
>     at org.apache.flink.streaming.connectors.kafka.Kafka09ITCase.testMultipleSourcesOnePartition(Kafka09ITCase.java:76)
>     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
>     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>     at java.lang.reflect.Method.invoke(Method.java:606)
>     at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
>     at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
>     at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
>     at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
>     at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:298)
>     at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:292)
>     at java.util.concurrent.FutureTask.run(FutureTask.java:262)
>     at java.lang.Thread.run(Thread.java:745)
> Caused by: org.apache.flink.runtime.client.JobExecutionException: Job execution failed.
>     at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$6.apply$mcV$sp(JobManager.scala:915)
>     at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$6.apply(JobManager.scala:858)
>     at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$6.apply(JobManager.scala:858)
>     at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
>     at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
>     at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:40)
>     at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:397)
>     at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
>     at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
>     at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
>     at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
> Caused by: java.lang.IllegalArgumentException: Restoring from a checkpoint / savepoint,
but found a partition state Partition: KafkaTopicPartition{topic='manyToOneTopic', partition=2},
KafkaPartitionHandle=manyToOneTopic-2, offset=(not set) that does not have a defined offset.
>     at org.apache.flink.streaming.connectors.kafka.internal.KafkaConsumerThread.<init>(KafkaConsumerThread.java:133)
>     at org.apache.flink.streaming.connectors.kafka.internal.Kafka09Fetcher.<init>(Kafka09Fetcher.java:113)
>     at org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer09.createFetcher(FlinkKafkaConsumer09.java:182)
>     at org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumerBase.run(FlinkKafkaConsumerBase.java:275)
>     at org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:78)
>     at org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:55)
>     at org.apache.flink.streaming.runtime.tasks.SourceStreamTask.run(SourceStreamTask.java:56)
>     at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:265)
>     at org.apache.flink.runtime.taskmanager.Task.run(Task.java:668)
>     at java.lang.Thread.run(Thread.java:745)
> {code}



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