This topic provides issues to consider when troubleshooting the Apache® Kafka® integration for Progress® OpenEdge® ABL.

Producer

The following troubleshooting tips apply to the Kafka client producer:

  • Invoking Producer:Flush() with a low number can result in a timeout error being raised from librdkafka indicating it was not able to process the producer’s send queue within the amount of time given. This often happens on the first message being sent as the client library needs to query cluster information which takes some amount of time. If this happens, you can try to address the issue by increasing the timeout or suppress the error by adding an exception handler and retrying the call to Flush().
  • Before allowing the producer to be garbage collected, ensure Flush() is called and returns without raising an error. If Flush() is not called before the producer is garbage collected, any messages left in the producer’s send queue may not get sent.
  • By default, the Kafka client’s maximum message size is 1MB. If the total message size exceeds this, the client raises an error when trying to send the message. This value may differ from the message broker’s configured maximum message size.
  • Some errors (for example, an inactive server) may not return an error to the application. Be sure to Enable logging at the appropriate level to see such errors in the log file. The following is an example log file error message (after setting logging level 2) for an inactive server:
    4GL MESSAGING 3 - ERROR: [thrd:app]: rdkafka#producer-1: vm-xxxxxxkafkabroker:4000/bootstrap: Failed to resolve 'vm-xxxxxxkafkabroker:4000': No such host is known. (after 4185ms in state CONNECT)

Consumer

The following troubleshooting tips apply to the Kafka client consumer:

  • You cannot create a Kafka consumer in Progress Application Server (PAS) for OpenEdge. If you try, an error is logged that states: "The Messaging Consumer is currently not supported in PASOE".

General

The following troubleshooting tips apply to both producers and consumers:

  • Errors related to SSL (for example, if ssl.ca.location is not set or if the SSL certificate is not installed) result in timeouts during send() or poll(). See the troubleshooting section in Configure SSL connections with Apache Kafka for more information.