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Iulian Dragos commented on SPARK-4631: -------------------------------------- [~advancedxy], I see the same exception in the logs. It's funny, but as I mentioned in my github account, things start working if I add a `Thread.sleep(50)` inside the loop, or a longer one before the call to {{publishData}}. On my machine it takes around 250ms for the Receiver to install its MQTT callback, and I think that's where the race condition is. If {{publishData}} finishes before that, no message is ever received on the Spark receiver end. I don't know much about MQTT, so I don't know if the service is supposed to queue those 100 messages and deliver them eventually. > Add real unit test for MQTT > ---------------------------- > > Key: SPARK-4631 > URL: https://issues.apache.org/jira/browse/SPARK-4631 > Project: Spark > Issue Type: Test > Components: Streaming > Reporter: Tathagata Das > Priority: Critical > Fix For: 1.3.0 > > > A real unit test that actually transfers data to ensure that the MQTTUtil is > functional -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org