Parallel and fault tolerant message processing for SQS endpoints.
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Key: CAMEL-5113
URL: https://issues.apache.org/jira/browse/CAMEL-5113
Project: Camel
Issue Type: Improvement
Components: camel-aws
Reporter: Daniel Carleton
I'm using Camel to implement parallel processing of jobs in an SQS queue, and
ran into a few issues with the current implementation of the SQS component:
# SqsConsumer uses a blocking/synchronous processor, which prevents parallel
processing of multiple messages from a single endpoint.
# Having a maxMessagesPerPoll other than one doesn't seem to make sense,
because any messages not being actively processed should be left back in the
queue for other consumers to have a chance with.
# Rollback processing doesn't go back to SQS and set the visibility timeout to
zero, which prevents immediate retries. (I guess if deleteAfterRead is turned
on this doesn't make sense, but then doesn't turning on deleteAfterRead break
fault tolerance completely?)
I propose the following solutions to these problems:
# Use an asynchronous processor in SqsConsumer by way of getAsyncProcessor().
(Messages in SQS aren't guaranteed to be FIFO anyway, so there should be no
issue with order of processing.)
# Replace maxMessagesPerPoll with maxInFlightMessages. Put a semaphore in
SqsConsumer to control the maximum number of in flight messages, and when
polling SQS always set the number of available permits as the maximum number of
messages to retrieve.
# In the onFailure callback for an exchange set the visibility timeout in SQS
to zero via ChangeMessageVisibility.
How does this sound? I'm working on a patch. This is my first work on Camel,
so if you see any problems with my approach let me know!
Thanks,
- Dan
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