[GitHub] [samza] mynameborat commented on a change in pull request #1213: [WIP] SAMZA-2305: Stream processor should ensure previous container is stopped during a rebalance

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mynameborat commented on a change in pull request #1213: [WIP] SAMZA-2305: Stream processor should ensure previous container is stopped during a rebalance
URL: https://github.com/apache/samza/pull/1213#discussion_r344404613
 
 

 ##########
 File path: samza-core/src/main/java/org/apache/samza/processor/StreamProcessor.java
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 @@ -461,8 +483,25 @@ public void onJobModelExpired() {
             } else {
               LOGGER.info("Container: {} shutdown completed for stream processor: {}.", container, processorId);
             }
+          } else if (state == State.IN_REBALANCE) {
+            if (container != null) {
+              boolean hasContainerShutdown = interruptSamzaContainer();
 
 Review comment:
   I agree that, it shuts down the executor service and the call site can instantiate a new one potentially based on its result. It currently shuts it down or not based on `container != null` and maybe i will extract that out from the method and establish a clear contract on this method where it will always invoke shutdownNow. By that, it is clear on the call site that upon invocation of this method, if executor service needs to used a new one needs to be created. 
   
   I prefer to use immutable method parameters wherever possible since its easier to reason about and also not worry about the side effects. In this case, this method is instance method anyways and IMO, I don't quite understand the benefit of passing the containerExecutorService as a method parameter.
   
   As far as creating an executor service upon success, I am debating whether to do it here vs create a new executor service in `onNewJobModel`. wdyt?

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