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https://issues.apache.org/jira/browse/ARTEMIS-921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15890330#comment-15890330
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Miroslav Novak commented on ARTEMIS-921:
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There is still a problem how producer msg/s rate is calculated in
{{QueueImpl.getRate()}} for slow consumer detection. It calculates only
messages added during the last {{queueRateCheckTime}} seconds. As this is used
to figure out, in which maximum msg/s rate the queue could serve the consumer
then it should also take into account messages which are already in queue at
{{queueRateCheckTime}} time.
Current implementation is problem for cases when messages are sent to queue in
bursts, for example producer sends 1000s messages in a few seconds and then
stops and will do that again in 1 hour. QueueImpl.getRate() method returns 0
msg/s for queueRateCheckTime which is by default 5 seconds and slow consumer
detection will be skipped (almost) all the time.
I tried to fix it by following change to QueueImpl.getRate() method and seems
to be ok, wdyt?
{code}
private final AtomicLong messageCountSnapshot = new AtomicLong(0);
public float getRate() {
long locaMessageAdded = getMessagesAdded();
float timeSlice = ((System.currentTimeMillis() -
queueRateCheckTime.getAndSet(System.currentTimeMillis())) / 1000.0f);
if (timeSlice == 0) {
messagesAddedSnapshot.getAndSet(locaMessageAdded);
return 0.0f;
}
return BigDecimal.valueOf(((locaMessageAdded -
messagesAddedSnapshot.getAndSet(locaMessageAdded)) +
messageCountSnapshot.getAndSet(getMessageCount())) / timeSlice).setScale(2,
BigDecimal.ROUND_UP).floatValue(); <-- here is the change
}
{code}
> Consumers killed as slow even if overall consuming rate is above threshold
> --------------------------------------------------------------------------
>
> Key: ARTEMIS-921
> URL: https://issues.apache.org/jira/browse/ARTEMIS-921
> Project: ActiveMQ Artemis
> Issue Type: Bug
> Components: Broker
> Affects Versions: 1.5.1
> Reporter: Howard Gao
> Assignee: clebert suconic
> Fix For: 1.5.2, 2.0.0
>
>
> We have one queue. Imagine messages are produced at 2 msgs/s. There are three
> consumers and slow consumer limit is 1 msgs/s. What happens is that all three
> consumers get killed as slow, even though it is impossible for any of them to
> be fast, since messages are distributed equally between the consumers
> (round-robin).
> This has real consumer impact in a situation when producer rate is usually
> high (so it requires multiple consumers working in parallel), but may
> occasionally drop close to consumer-threshold. In this case, broker
> disconnects all consumers who then have to reconnect and message processing
> is delayed for the time of the reconnecting.
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