Github user hmcl commented on a diff in the pull request: https://github.com/apache/storm/pull/1679#discussion_r86892802 --- Diff: external/storm-kafka-client/src/main/java/org/apache/storm/kafka/spout/KafkaSpout.java --- @@ -479,16 +487,17 @@ public OffsetAndMetadata findNextCommitOffset() { KafkaSpoutMessageId nextCommitMsg = null; // this is a convenience variable to make it faster to create OffsetAndMetadata for (KafkaSpoutMessageId currAckedMsg : ackedMsgs) { // complexity is that of a linear scan on a TreeMap - if ((currOffset = currAckedMsg.offset()) == initialFetchOffset || currOffset == nextCommitOffset + 1) { // found the next offset to commit + if ((currOffset = currAckedMsg.offset()) == nextCommitOffset + 1) { // found the next offset to commit found = true; nextCommitMsg = currAckedMsg; nextCommitOffset = currOffset; } else if (currAckedMsg.offset() > nextCommitOffset + 1) { // offset found is not continuous to the offsets listed to go in the next commit, so stop search LOG.debug("topic-partition [{}] has non-continuous offset [{}]. It will be processed in a subsequent batch.", tp, currOffset); break; } else { - LOG.debug("topic-partition [{}] has unexpected offset [{}].", tp, currOffset); - break; + //Received a redundant ack. Ignore and continue processing. --- End diff -- @jfenc91 @srdo This behavior still seems quite surprising to me. However, this fix probably won't have any bad side effect, so it should be OK. Perhaps you can add to the log message that we are ignoring it as it is out of order, duplicate, or something like that. @revans2 can you please comment on why, or if it is possible a tuple to be acked more than once?
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