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https://issues.apache.org/jira/browse/SAMZA-503?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14281106#comment-14281106
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Chris Riccomini commented on SAMZA-503:
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[~closeuris], regarding the patch you posted, it'd be nice if we added a
"high-watermark" gauge, that stored the absolute high watermark. Now that we're
refreshing this on a regular basis, it'd be nice to have that metric exposed,
in addition to the diff with the next offset.
Exposing this offset also means that metric systems (Ganglia, etc) could be
used to calculate the diff between the "high-watermark" value and the
"<system>-<stream>-<partition>-offset" gauge. This would be a way to get the
diff between (1) and (3).
> Lag gauge very slow to update for slow jobs
> -------------------------------------------
>
> Key: SAMZA-503
> URL: https://issues.apache.org/jira/browse/SAMZA-503
> Project: Samza
> Issue Type: Bug
> Components: metrics
> Affects Versions: 0.8.0
> Environment: Mac OS X, Oracle Java 7, ProcessJobFactory
> Reporter: Roger Hoover
> Assignee: Yan Fang
> Fix For: 0.9.0
>
> Attachments: SAMZA-503.patch
>
>
> For slow jobs, the
> KafkaSystemConsumerMetrics.%s-%s-messages-behind-high-watermark) gauge does
> not get updated very often.
> To reproduce:
> * Create a job that processes one message and sleeps for 5 seconds
> * Create it's input topic but do not populate it yet
> * Start the job
> * Load 1000s of messages to it's input topic. You can keep adding messages
> with a "wait -n 1 <kafka console producer command>"
> What happens:
> * Run jconsole to view the JMX metrics
> * The %s-%s-messages-behind-high-watermark gauge will stay at 0 for a LONG
> time (~10 minutes?) before finally updating.
> What should happen:
> * The gauge should get updated at a reasonable interval (a least every few
> seconds)
> I think what's happening is that the BrokerProxy only updates the high
> watermark when a consumer is ready for more messages. When the job is so
> slow, this rarely happens to the metric doesn't get updated.
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