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https://issues.apache.org/jira/browse/BEAM-11034?focusedWorklogId=499496&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-499496
 ]

ASF GitHub Bot logged work on BEAM-11034:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 12/Oct/20 16:16
            Start Date: 12/Oct/20 16:16
    Worklog Time Spent: 10m 
      Work Description: kennknowles commented on a change in pull request 
#13032:
URL: https://github.com/apache/beam/pull/13032#discussion_r503400133



##########
File path: 
runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/SimpleParDoFn.java
##########
@@ -486,14 +487,23 @@ private void processTimers(
     for (W window : windowsToCleanup) {
       // The stepContext is the thing that know if it is batch or streaming, 
hence
       // whether state needs to be cleaned up or will simply be discarded so 
the
-      // timer can be ignored
-
+      // timer can be ignored.
       Instant cleanupTime = earliestAllowableCleanupTime(window, 
windowingStrategy);
-      // if DoFn has OnWindowExpiration then set holds for system timer.
-      Instant cleanupOutputTimestamp =
-          fnSignature.onWindowExpiration() == null ? cleanupTime : 
cleanupTime.minus(1L);
-      stepContext.setStateCleanupTimer(
-          CLEANUP_TIMER_ID, window, windowCoder, cleanupTime, 
cleanupOutputTimestamp);
+      // Set a cleanup timer for state at the end of the window to trigger 
onWindowExpiration and
+      // garbage collect state. We avoid doing this for the global window if 
there is no window
+      // expiration set as the state will be up when the pipeline terminates. 
Setting the timer
+      // leads to a unbounded growth of timers for pipelines with many unique 
keys in the global
+      // window.
+      if (cleanupTime.isBefore(GlobalWindow.INSTANCE.maxTimestamp())

Review comment:
       Re-reading the bug and thinking about your comments, can we eliminate 
this condition and invoke from some `onDrain` method?




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Issue Time Tracking
-------------------

    Worklog Id:     (was: 499496)
    Time Spent: 1h 40m  (was: 1.5h)

> State garbage collection timers set by Dataflow SimpleParDoFn pile up for the 
> GlobalWindow
> ------------------------------------------------------------------------------------------
>
>                 Key: BEAM-11034
>                 URL: https://issues.apache.org/jira/browse/BEAM-11034
>             Project: Beam
>          Issue Type: Bug
>          Components: runner-dataflow
>            Reporter: Sam Whittle
>            Assignee: Sam Whittle
>            Priority: P2
>          Time Spent: 1h 40m
>  Remaining Estimate: 0h
>
> If the dofn is stateful, garbage collection timers are set for the end of the 
> window plus allowed lateness:
> https://github.com/apache/beam/blob/6fdde4f4eab72b49b10a8bb1cb3be263c5c416b5/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/SimpleParDoFn.java#L491
> For the global window this ends up setting garbage collection timers that 
> will only fire once the pipeline is drained.  For pipelines that have 
> constantly newly arriving unique stateful keys, and otherwise cleanup their 
> state appropriately when triggering occurs, the # of timers builds up over 
> time.
> Example window and trigger, where the user has the opportunity to clean up 
> state for the key after at most a minute.  However they have no control over 
> the timer set.
> GlobalWindows()
> .triggering(Repeatedly.forever(AfterFirst.of(
> AfterPane.elementCountAtLeast(5000),
> AfterProcessingTime.pastFirstElementInPane().plusDelayOf(Duration.standardMi
> nutes(1))).discardingFiredPanes().withAllowedLateness(Duration.ZERO);



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