[jira] [Created] (FLINK-10195) RabbitMQ Source With Checkpointing Doesn't Backpressure Correctly

["Luka Jurukovski (JIRA)" <ji...@apache.org>]

Luka Jurukovski created FLINK-10195:
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             Summary: RabbitMQ Source With Checkpointing Doesn't Backpressure Correctly
                 Key: FLINK-10195
                 URL: https://issues.apache.org/jira/browse/FLINK-10195
             Project: Flink
          Issue Type: Bug
          Components: RabbitMQ Connector
    Affects Versions: 1.6.0, 1.5.1, 1.5.0, 1.4.0
            Reporter: Luka Jurukovski


The connection between the RabbitMQ server and the client does not appropriately back pressure when auto acking is disabled. This becomes very problematic when a downstream process throttles the data processing to slower then RabbitMQ sends the data to the client.

The difference in records ends up being stored in the flink's heap space, which grows indefinitely (or technically to "Integer Max" Deliveries). Looking at RabbitMQ's metrics the number of unacked messages looks like steadily rising saw tooth shape.

Upon further invesitgation it looks like this is due to how the QueueingConsumer works, messages are added to the BlockingQueue faster then they are being removed and processed, resulting in the previously described behavior.

This may be intended behavior, however this isn't explicitly obvious in the documentation or any of the examples I have seen.



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