[jira] [Comment Edited] (FLINK-18196) flink throws `NullPointerException` when executeCheckpointing

["Piotr Nowojski (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-18196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17211216#comment-17211216 ] 

Piotr Nowojski edited comment on FLINK-18196 at 10/9/20, 5:31 PM:
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By looking at the code, it's impossible for this NPE to happen. As it was previously reported that upgrading JDK fixed the problem, I'm pretty sure this must be some weird JDK bug. I'm closing this issue for now. 

For anyone reporting/re-opening this issue, please state what JDK version are you using, and if it's older then  jdk1.8.0_251, please upgrade to at least that version before reporting it.


was (Author: pnowojski):
By looking at the code, it's impossible for this NPE to happen. As it was previously reported that upgrading JDK fixed the problem, I'm pretty sure this must be some weird JDK bug. I'm closing this issue for now. 

For anyone reporting/re-opening this issue, please state what JDK version are you using, and if it's older then  jdk1.8.0_251, please upgrade to at least that version.

> flink throws `NullPointerException` when executeCheckpointing
> -------------------------------------------------------------
>
>                 Key: FLINK-18196
>                 URL: https://issues.apache.org/jira/browse/FLINK-18196
>             Project: Flink
>          Issue Type: Bug
>          Components: Runtime / Checkpointing
>    Affects Versions: 1.10.0, 1.10.1
>         Environment: flink version: flink-1.10.0 flink-1.10.1
> jdk version: jdk1.8.0_40
>            Reporter: Kai Chen
>            Priority: Major
>             Fix For: 1.12.0, 1.10.3, 1.11.3
>
>
> I meet checkpoint NPE when executing wordcount example:
> java.lang.Exception: Could not perform checkpoint 5505 for operator Source: KafkaTableSource(xxx) > SourceConversion(table=[xxx, source: [KafkaTableSource(xxx)]], fields=[xxx]) > Calc(select=[xxx) AS xxx]) > SinkConversionToTuple2  --  > Sink: Elasticsearch6UpsertTableSink(xxx) (1/1).
>     at org.apache.flink.streaming.runtime.tasks.StreamTask.triggerCheckpoint(StreamTask.java:802)
>     at org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$triggerCheckpointAsync$3(StreamTask.java:777)
>     at org.apache.flink.streaming.runtime.tasks.StreamTask$$Lambda$228/1024478318.call(Unknown Source)
>     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
>     at org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$SynchronizedStreamTaskActionExecutor.run(StreamTaskActionExecutor.java:87)
>     at org.apache.flink.streaming.runtime.tasks.mailbox.Mail.run(Mail.java:78)
>     at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.processMail(MailboxProcessor.java:261)
>     at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.runMailboxLoop(MailboxProcessor.java:186)
>     at org.apache.flink.streaming.runtime.tasks.StreamTask.runMailboxLoop(StreamTask.java:487)
>     at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:470)
>     at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:707)
>     at org.apache.flink.runtime.taskmanager.Task.run(Task.java:532)
>     at java.lang.Thread.run(Thread.java:745)
> Caused by: java.lang.NullPointerException
>     at org.apache.flink.streaming.runtime.tasks.StreamTask$CheckpointingOperation.executeCheckpointing(StreamTask.java:1411)
>     at org.apache.flink.streaming.runtime.tasks.StreamTask.checkpointState(StreamTask.java:991)
>     at org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$performCheckpoint$5(StreamTask.java:887)
>     at org.apache.flink.streaming.runtime.tasks.StreamTask$$Lambda$229/1010499540.run(Unknown Source)
>     at org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$SynchronizedStreamTaskActionExecutor.runThrowing(StreamTaskActionExecutor.java:94)
>     at org.apache.flink.streaming.runtime.tasks.StreamTask.performCheckpoint(StreamTask.java:860)
>     at org.apache.flink.streaming.runtime.tasks.StreamTask.triggerCheckpoint(StreamTask.java:793)
>     ... 12 more
>  
> checkpoint configuration
> |Checkpointing Mode|Exactly Once|
> |Interval|5s|
> |Timeout|10m 0s|
> |Minimum Pause Between Checkpoints|0ms|
> |Maximum Concurrent Checkpoints|1|
> With debug enabled, I found `checkpointMetaData`  is null at
>  [https://github.com/apache/flink/blob/release-1.10.0/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/tasks/StreamTask.java#L1421]
>  
> I fixed this with this patch: [https://github.com/yuchuanchen/flink/commit/e5122d9787be1fee9bce141887e0d70c9b0a4f19]



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