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https://issues.apache.org/jira/browse/SAMZA-503?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14280967#comment-14280967
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Yan Fang commented on SAMZA-503:
--------------------------------

{quote}
The MBHW metric should get updated even when the BrokerProxy thread doesn't 
need to fetch more messages.
{quote}

I had the patch. RB: https://reviews.apache.org/r/29993/

The only question is, since earliestOrLatestOffset method accepts an int for 
the consumerId, do not know which number i should use. Just put the hashcode of 
the clientId...

> 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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