Vivek Mittal created STORM-2505:
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Summary: Kafka Spout doesn't support voids in the topic
Key: STORM-2505
URL: https://issues.apache.org/jira/browse/STORM-2505
Project: Apache Storm
Issue Type: Bug
Components: storm-kafka
Affects Versions: 1.x
Reporter: Vivek Mittal
Kafka maintains the spout progress (offsets for partitions) which can hold a
value which no longer exists (or offset+1 doesn't exist) in the topic due to
following reasons
* Topology stopped processing (or died) & topic got compacted
(cleanup.policy=compact) leaving offset voids in the topic.
* Topology stopped processing (or died) & Topic got cleaned up
(cleanup.policy=delete) and the offset.
When the topology starts processing again (or restarted), the spout logic
suggests that the next offset has to be (committedOffset+1) for the spout to
make progress, which will never be the case as (committedOffset+1) has been
removed from the topic and will never be acked.
{code:title=OffsetManager.java|borderStyle=solid}
// Some comments here
if (currOffset == nextCommitOffset + 1) { // found the next offset
to commit
found = true;
nextCommitMsg = currAckedMsg;
nextCommitOffset = currOffset;
} else if (currOffset > nextCommitOffset + 1) {
LOG.debug("topic-partition [{}] has non-continuous offset [{}].
It will be processed in a subsequent batch.", tp, currOffset);
}
{code}
A smart forwarding mechanism has to be built so as to forward the spout pivot
to the next logical location, instead of a hardcoded single forward operation.
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