[jira] [Created] (FLINK-13806) Metric Fetcher floods the JM log with errors when TM is lost

["Stephan Ewen (Jira)" <ji...@apache.org>]

Stephan Ewen created FLINK-13806:
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             Summary: Metric Fetcher floods the JM log with errors when TM is lost
                 Key: FLINK-13806
                 URL: https://issues.apache.org/jira/browse/FLINK-13806
             Project: Flink
          Issue Type: Bug
          Components: Runtime / Metrics
    Affects Versions: 1.9.0
            Reporter: Stephan Ewen
             Fix For: 1.10.0, 1.9.1


When a task manager is lost, the log contains a series of exceptions from the metrics fetcher, making it hard to identify the exceptions from the actual job failure.

The exception below is contained multiple time (in my example eight times) in a simple 4 TM setup after one TM failure.

I would suggest to suppress "failed asks" (timeouts) from the metrics fetcher service, because the fetcher has not enough information to distinguish between root cause exceptions and follow-up exceptions. In most cases, these exceptions should be follow-up to a failure that is handled in the scheduler/ExecutionGraph already, and the additional exception logging only add noise to the log.

{code}
2019-08-20 22:00:09,865 WARN  org.apache.flink.runtime.rest.handler.legacy.metrics.MetricFetcherImpl  - Requesting TaskManager's path for query services failed.
java.util.concurrent.CompletionException: akka.pattern.AskTimeoutException: Ask timed out on [Actor[akka://flink/user/dispatcher#-1834666306]] after [10000 ms]. Message of type [org.apache.flink.runtime.rpc.messages.LocalFencedMessage]. A typical reason for `AskTimeoutException` is that the recipient actor didn't send a reply.
        at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:292)
        at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:308)
        at java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:593)
        at java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:577)
        at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474)
        at java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:1977)
        at org.apache.flink.runtime.concurrent.FutureUtils$1.onComplete(FutureUtils.java:871)
        at akka.dispatch.OnComplete.internal(Future.scala:263)
        at akka.dispatch.OnComplete.internal(Future.scala:261)
        at akka.dispatch.japi$CallbackBridge.apply(Future.scala:191)
        at akka.dispatch.japi$CallbackBridge.apply(Future.scala:188)
        at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:36)
        at org.apache.flink.runtime.concurrent.Executors$DirectExecutionContext.execute(Executors.java:74)
        at scala.concurrent.impl.CallbackRunnable.executeWithValue(Promise.scala:44)
        at scala.concurrent.impl.Promise$DefaultPromise.tryComplete(Promise.scala:252)
        at akka.pattern.PromiseActorRef$$anonfun$1.apply$mcV$sp(AskSupport.scala:644)
        at akka.actor.Scheduler$$anon$4.run(Scheduler.scala:205)
        at scala.concurrent.Future$InternalCallbackExecutor$.unbatchedExecute(Future.scala:601)
        at scala.concurrent.BatchingExecutor$class.execute(BatchingExecutor.scala:109)
        at scala.concurrent.Future$InternalCallbackExecutor$.execute(Future.scala:599)
        at akka.actor.LightArrayRevolverScheduler$TaskHolder.executeTask(LightArrayRevolverScheduler.scala:328)
        at akka.actor.LightArrayRevolverScheduler$$anon$4.executeBucket$1(LightArrayRevolverScheduler.scala:279)
        at akka.actor.LightArrayRevolverScheduler$$anon$4.nextTick(LightArrayRevolverScheduler.scala:283)
        at akka.actor.LightArrayRevolverScheduler$$anon$4.run(LightArrayRevolverScheduler.scala:235)
        at java.lang.Thread.run(Thread.java:748)
Caused by: akka.pattern.AskTimeoutException: Ask timed out on [Actor[akka://flink/user/dispatcher#-1834666306]] after [10000 ms]. Message of type [org.apache.flink.runtime.rpc.messages.LocalFencedMessage]. A typical reason for `AskTimeoutException` is that the recipient actor didn't send a reply.
        at akka.pattern.PromiseActorRef$$anonfun$2.apply(AskSupport.scala:635)
        at akka.pattern.PromiseActorRef$$anonfun$2.apply(AskSupport.scala:635)
        at akka.pattern.PromiseActorRef$$anonfun$1.apply$mcV$sp(AskSupport.scala:648)
        ... 9 more
{code}




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