Hello, I am trying to modify the parallelism of a streaming Flink job (wiki-edits example) multiple times on a standalone cluster (one local machine) having two TaskManagers with 3 slots each (i.e. 6 slots total). However, the "modify" command is only working once (e.g. when I change the parallelism from 2 to 4). The second time (e.g. change parallelism to 6 or even back to 2), it is giving an error.
I am using Flink 1.8.1 (since I found that the modify parallelism command has been removed from v1.9 documentation) and have configured savepoints to be written to file:///home/pankaj/flink-checkpoints. The output of the first "modify <jobid> -p 4" command and second "modify <jobid> -p 6" command is copied below. Please tell me how to modify parallelism multiple times at runtime. Thanks, Pankaj $ ./bin/flink modify 94831ca34951975dbee3335a384ee935 -p 4 Modify job 94831ca34951975dbee3335a384ee935. Rescaled job 94831ca34951975dbee3335a384ee935. Its new parallelism is 4. $ ./bin/flink modify 94831ca34951975dbee3335a384ee935 -p 6 Modify job 94831ca34951975dbee3335a384ee935. ------------------------------------------------------------ The program finished with the following exception: org.apache.flink.util.FlinkException: Could not rescale job 94831ca34951975dbee3335a384ee935. at org.apache.flink.client.cli.CliFrontend.lambda$modify$10(CliFrontend.java:799) at org.apache.flink.client.cli.CliFrontend.runClusterAction(CliFrontend.java:985) at org.apache.flink.client.cli.CliFrontend.modify(CliFrontend.java:790) at org.apache.flink.client.cli.CliFrontend.parseParameters(CliFrontend.java:1068) at org.apache.flink.client.cli.CliFrontend.lambda$main$11(CliFrontend.java:1126) at org.apache.flink.runtime.security.NoOpSecurityContext.runSecured(NoOpSecurityContext.java:30) at org.apache.flink.client.cli.CliFrontend.main(CliFrontend.java:1126) Caused by: java.util.concurrent.CompletionException: java.lang.IllegalStateException: Suspend needs to happen atomically at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:273) at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:280) at java.util.concurrent.CompletableFuture.uniCompose(CompletableFuture.java:961) at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:926) at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:442) at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleRunAsync(AkkaRpcActor.java:392) at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleRpcMessage(AkkaRpcActor.java:185) at org.apache.flink.runtime.rpc.akka.FencedAkkaRpcActor.handleRpcMessage(FencedAkkaRpcActor.java:74) at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.onReceive(AkkaRpcActor.java:147) at org.apache.flink.runtime.rpc.akka.FencedAkkaRpcActor.onReceive(FencedAkkaRpcActor.java:40) at akka.actor.UntypedActor$$anonfun$receive$1.applyOrElse(UntypedActor.scala:165) at akka.actor.Actor.aroundReceive(Actor.scala:502) at akka.actor.Actor.aroundReceive$(Actor.scala:500) at akka.actor.UntypedActor.aroundReceive(UntypedActor.scala:95) at akka.actor.ActorCell.receiveMessage(ActorCell.scala:526) at akka.actor.ActorCell.invoke(ActorCell.scala:495) at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:257) at akka.dispatch.Mailbox.run(Mailbox.scala:224) at akka.dispatch.Mailbox.exec(Mailbox.scala:234) at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289) at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056) at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692) at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157) Caused by: java.lang.IllegalStateException: Suspend needs to happen atomically at org.apache.flink.util.Preconditions.checkState(Preconditions.java:195) at org.apache.flink.runtime.executiongraph.ExecutionGraph.suspend(ExecutionGraph.java:1172) at org.apache.flink.runtime.jobmaster.JobMaster.suspendExecutionGraph(JobMaster.java:1221) at org.apache.flink.runtime.jobmaster.JobMaster.lambda$rescaleOperators$5(JobMaster.java:465) at java.util.concurrent.CompletableFuture.uniCompose(CompletableFuture.java:952) ... 20 more
