EMA Java Status messages "Slow Consumer" and "Data was lost for this security". Cannot repeat.

duncan_kerr
duncan_kerr Explorer
in EMA

Hi - I am trying to recreate a slow RMDS consumer scenario we have seen using EMA Java 3.6.0. I can repeat all the channel and ticker status messages, but in one instance we saw this status message:

Received status msg: text:Slow Consumer, statusCode:None, data:Ok, stream:Open

do you recognize this message. When would we expect to see it, exactly?

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Best Answer

  • zoya faberov
    zoya faberov ✭✭✭✭✭
    Answer ✓

    Hello @duncan_kerr ,

    Please refer to this previous discussion thread on A27.

    However, in my observation, this discussion's focus seems to have moved away from EMA development, and into infrastructure configuration, and likely configuration related issues.

    It may be that there is a local configuration issue, or tuning is required, but this forum is intended and best able to help with general API usage questions, not really equipped to help diagnose and troubleshoot infra configuration issues.

    Suggest to report the errors that you are observing to your local market data admin/group in charge of the infra, hopefully they can address/help explain the happenings.

Answers

  • zoya faberov
    zoya faberov ✭✭✭✭✭

    Hello @duncan_kerr ,

    "Slow consumer" problem, referring to a consumer that is not handling the update traffic in a timely manner, and causing the buffers overflow, is detected by the infra. It often results in disconnects, which are very visible, highly undesirable and usually are the first focus.

    If there was no disconnect, then the situation that you have observed was likely not as severe, and might have resulted in "slow consumer" warning, but without next being a disconnect from the infra. If there was a consequent disconnect, that would make the scenario common.

    I would say a way to recreate a slow consumer scenario in general, it to make on message callbacks long and slow, "hang on" to callbacks, so the callbacks don't return, by putting delays or sleeps inside the callbacks. This should help to reproduce the slow consumer problem in general, as I understand you are looking to reproduce and to capture, if not this specific message.



  • duncan_kerr
    duncan_kerr Explorer
    https://community.developers.refinitiv.com/discussion/comment/95854#Comment_95854
    Hi Zoya - I was hoping to repeat the slow consumer warning. I can easily repeat the channel down disconnect by slowing down my consumer.. Presumably I'd just need to adjust my callback processing delay to the exact correct level to trigger the warning without triggering the disconnect.
  • duncan_kerr
    duncan_kerr Explorer

    Hi Zoya - we also see the following message in our application, which was possibly a slow c. Can you explain when we'd expect to see this message? I suspect its a problem with our resubscription logic, but if you have seen the "data was lost" message before it'd be of interest.

    SubscriptionStatus{subscriptionState=FAILURE, subscriptionMessage=UNKNOWN Subscription terminated: Data was lost for this security}
  • duncan_kerr
    duncan_kerr Explorer

    Hi Zoya - here's another message from the same period, would you be able to explain? Is there a reference to these error messages I can access?

    A27: Synchronization Error. Recalling.

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