Hi Zakelly, Yes, this job contains both operator state and keyed state. Happy to provide more details as needed.
Kevin On Mon, Sep 8, 2025 at 10:48 PM Zakelly Lan <[email protected]> wrote: > Hi Kevin, > > One more thing I want to make sure about the job. Is this a datastream job > with operator state (not only keyed states after `keyby()`)? > > > Thanks! > > Best, > Zakelly > > On Fri, Sep 5, 2025 at 9:53 PM Kevin Kim <[email protected]> > wrote: > >> Thanks so much! >> >> More context: this file merging feature is really promising for our use >> case. Given the large state size and parallelism, we occasionally run into >> S3 rate limits at checkpoint/savepoint time. >> >> The few times I tried this file merging, it helped quite a bit, but I've >> had to turn it off for now due to this NPE, which happens occasionally but >> not always >> >> On Fri, Sep 5, 2025, 1:58 AM Gabor Somogyi <[email protected]> >> wrote: >> >>> Hi Guys, >>> >>> This sounds severe and I'm also taking a look... >>> >>> G >>> >>> >>> On Fri, Sep 5, 2025 at 4:44 AM Zakelly Lan <[email protected]> >>> wrote: >>> >>>> Hi Kevin, >>>> >>>> Thanks for the details. It's really helpful. I'm trying to reproduce >>>> this according to your setup. Will let you know if any updates. >>>> >>>> I create a jira issue to track this: >>>> https://issues.apache.org/jira/browse/FLINK-38327 >>>> >>>> >>>> Best, >>>> Zakelly >>>> >>>> On Thu, Sep 4, 2025 at 7:42 PM Kevin Kim < >>>> [email protected]> wrote: >>>> >>>>> Hi Zakelly, >>>>> >>>>> Thanks for the reply. >>>>> >>>>> This job is running on Kubernetes using the Apache Flink Kubernetes >>>>> operator. This NullPointerException happened during a job restart after >>>>> one >>>>> of the TaskManagers restarted because the underlying node running the >>>>> TaskManager pod was scaled down for maintenance. There was no rescaling or >>>>> parallelism change. >>>>> >>>>> The job is quite large due to heavy input traffic + state size: >>>>> 2100 parallelism >>>>> taskmanager.numberOfTaskSlots: 14 (so 150 TaskManagers total) >>>>> RocksDBStateBackend used for state management. Checkpoints/savepoints >>>>> are written to S3 in AWS. >>>>> According to the Flink Checkpoint UI, the full state size is ~600GB >>>>> >>>>> Please let me know if more details would be helpful. >>>>> >>>>> Best regards, >>>>> Kevin >>>>> >>>>> >>>>> On Thu, Sep 4, 2025 at 6:16 AM Zakelly Lan <[email protected]> >>>>> wrote: >>>>> >>>>>> Hi Kevin, >>>>>> >>>>>> Would you please provide more info about the setup? Is this a >>>>>> failover or manual job restart with or without a change of parallelism >>>>>> (rescale)? >>>>>> >>>>>> >>>>>> Best, >>>>>> Zakelly >>>>>> >>>>>> >>>>>> >>>>>> On Wed, Sep 3, 2025 at 2:43 AM Kevin Kim <[email protected]> wrote: >>>>>> >>>>>>> Has anyone seen this NullPointerException after enabling checkpoint >>>>>>> file merging? I'm running a job with Flink 1.20.2 with these configs: >>>>>>> >>>>>>> execution.checkpointing.file-merging.enabled: true >>>>>>> execution.checkpointing.file-merging.max-file-size: 32m >>>>>>> execution.checkpointing.timeout: "10min" >>>>>>> execution.checkpointing.tolerable-failed-checkpoints: 3 >>>>>>> execution.checkpointing.min-pause: "2min" >>>>>>> execution.checkpointing.interval: "2min" >>>>>>> >>>>>>> java.lang.NullPointerException >>>>>>> at >>>>>>> org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManagerBase.isManagedByFileMergingManager(FileMergingSnapshotManagerBase.java:927) >>>>>>> at >>>>>>> org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManagerBase.lambda$restoreStateHandles$11(FileMergingSnapshotManagerBase.java:866) >>>>>>> at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1220) >>>>>>> at >>>>>>> org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManagerBase.lambda$restoreStateHandles$12(FileMergingSnapshotManagerBase.java:861) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) >>>>>>> at >>>>>>> java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:276) >>>>>>> at >>>>>>> java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:992) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:276) >>>>>>> at >>>>>>> java.base/java.util.ArrayList$Itr.forEachRemaining(ArrayList.java:1003) >>>>>>> at >>>>>>> java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1845) >>>>>>> at >>>>>>> java.base/java.util.stream.Streams$ConcatSpliterator.forEachRemaining(Streams.java:734) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:276) >>>>>>> at >>>>>>> java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:992) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) >>>>>>> at >>>>>>> java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) >>>>>>> at >>>>>>> java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) >>>>>>> at >>>>>>> java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) >>>>>>> at >>>>>>> org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManagerBase.restoreStateHandles(FileMergingSnapshotManagerBase.java:858) >>>>>>> at >>>>>>> org.apache.flink.runtime.checkpoint.filemerging.SubtaskFileMergingManagerRestoreOperation.restore(SubtaskFileMergingManagerRestoreOperation.java:102) >>>>>>> at >>>>>>> org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.registerRestoredStateToFileMergingManager(StreamTaskStateInitializerImpl.java:353) >>>>>>> at >>>>>>> org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.streamOperatorStateContext(StreamTaskStateInitializerImpl.java:163) >>>>>>> at >>>>>>> org.apache.flink.streaming.api.operators.AbstractStreamOperator.initializeState(AbstractStreamOperator.java:275) >>>>>>> at >>>>>>> org.apache.flink.streaming.runtime.tasks.RegularOperatorChain.initializeStateAndOpenOperators(RegularOperatorChain.java:106) >>>>>>> at >>>>>>> org.apache.flink.streaming.runtime.tasks.StreamTask.restoreStateAndGates(StreamTask.java:858) >>>>>>> at >>>>>>> org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$restoreInternal$5(StreamTask.java:812) >>>>>>> at >>>>>>> org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$1.call(StreamTaskActionExecutor.java:55) >>>>>>> at >>>>>>> org.apache.flink.streaming.runtime.tasks.StreamTask.restoreInternal(StreamTask.java:812) >>>>>>> at >>>>>>> org.apache.flink.streaming.runtime.tasks.StreamTask.restore(StreamTask.java:771) >>>>>>> at >>>>>>> org.apache.flink.runtime.taskmanager.Task.runWithSystemExitMonitoring(Task.java:970) >>>>>>> at >>>>>>> org.apache.flink.runtime.taskmanager.Task.restoreAndInvoke(Task.java:939) >>>>>>> at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:763) >>>>>>> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:575) >>>>>>> at java.base/java.lang.Thread.run(Thread.java:840) >>>>>>> >>>>>>
