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  1. Apache Storm
  2. STORM-3501

Local Cluster worker restarts




      I was trying to launch a topology that I'm developing (in 2.0.0) and noticed that the worker was getting restarted each ~30 seconds. 
      I placed a breakpoint in the kill method of LocalContainer (https://github.com/apache/storm/blob/2ba95bbd1c911d4fc6363b1c4b9c4c6d86ac9aae/storm-server/src/main/java/org/apache/storm/daemon/supervisor/LocalContainer.java#L66) to try and understand why the worker was getting restarted. 
      The call stack was:
      _kill:66, LocalContainer (org.apache.storm.daemon.supervisor)
      killContainerFor:269, Slot (org.apache.storm.daemon.supervisor)
      handleRunning:724, Slot (org.apache.storm.daemon.supervisor)
      stateMachineStep:218, Slot (org.apache.storm.daemon.supervisor)
      run:931, Slot (org.apache.storm.daemon.supervisor) _
      With this I can understand that the worker is killed because a blob has changed (https://github.com/apache/storm/blob/2ba95bbd1c911d4fc6363b1c4b9c4c6d86ac9aae/storm-server/src/main/java/org/apache/storm/daemon/supervisor/Slot.java#L724). In fact, there's a changing blob in the dynamicState at that point.
      I checked the AsyncLocalizer which downloads, caches blobs locally, and notifies the Slot state machine of a changing blob.
      I noticed this:

      Which tell me that (correct me if I'm wrong):

      • Supervisor tries to update blobs each 30 seconds.
      • The topology jar blob requires extraction of the resources directory (either from a jar or directly in a classpath URL). It does so in fetchUnzipToTemp and it's existence is checked in isFullyDownloaded.
      • The Slot is notified of a changing blob if:
      • the remote version is different from the local version (the code has changed).
      • OR the blob is not fully downloaded (the jar exists, and the extracted resources directory exists).

      Well, I did not have a resources folder under the root of the classpath, and that's why the worker was being restarted each ~30 seconds, as the Slot was being notified of a changing blob everytime updateBlobs ran. 
      I created a resources folder (with dummy files) under the root of the classpath and the problem is now solved.
      However, if I understand correctly, the resources folder is only required for multilang. Our topologies do not use multilang and this do not happen in Storm 1.1.3 for instance.


      Happy to submit MR.


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              • Assignee:
                diogopmonteiro Diogo Monteiro
                diogopmonteiro Diogo Monteiro
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