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  • Keith Donnell 81 posts 186 karma points
    Oct 03, 2017 @ 16:14
    Keith Donnell

    Umbraco 7.6.0 - Site becomes unresponsive for several minutes every day

    We've been having a problem for several months where the site becomes completely unresponsive for 5-15 minutes every day. We have added a ton of request logging, enabled DEBUG logging, and have finally found a pattern: Approximately 2 minutes prior to the outages (in every single log file I've looked at, going back to the beginning), the following lines appear:

    2017-09-26 15:13:05,652 [P7940/D9/T76] DEBUG Umbraco.Web.PublishedCache.XmlPublishedCache.XmlCacheFilePersister - Timer: release. 2017-09-26 15:13:05,652 [P7940/D9/T76] DEBUG Umbraco.Web.PublishedCache.XmlPublishedCache.XmlCacheFilePersister - Run now (sync).

    From what I gather this is the process that rebuilds the umbraco.config, correct?

    We have ~40,000 nodes, so I can't imagine this would be the quickest process to complete, however the strange thing is that the CPU and Memory on the Azure Web App do not spike during these outages. This would seem to point to the fact that the disk I/O is the bottleneck.

    This raises a few questions:

    1. Is there a way to schedule this task in a way that it only runs during off-peak hours?
    2. Are there performance improvements in the newer versions (we're on 7.6.0) that might improve this functionality?
    3. Are there any other suggestions to help correct this behavior?

    Hosting environment:

    • Azure App Service B2 (Basic)
    • SQL Azure Standard (20 DTUs) - DTU usage peaks at 20%, so I don't think there's anything there. Just noting for completeness
    • Azure Storage for media
    • Azure CDN for media requests

    Thank you so much in advance.

    UPDATE 10/4/2017

    If it helps, it appears that these particular log entries correspond with the first publish of the day (doesn't appear to matter what content is published).

    UPDATE 10/11/2017

    Since we haven't been able to find any reason for this issue, we will be upgrading to 7.7.2, and hoping the issue has been resolved. I will update here once we have more information.

  • Jonathan Richards 252 posts 1554 karma points MVP
    Oct 12, 2017 @ 09:19
    Jonathan Richards

    Hi Keith,

    I'm worried to respond, as I might be wrong, but I'm guessing this is around the core Umbraco trying to serialize the cache. Have you tried disabling it?

    Add the following to your

    <add key="umbracoContentXMLUseLocalTemp" value="true" /> 

    Some background info about it


  • Keith Donnell 81 posts 186 karma points
    Oct 13, 2017 @ 14:18
    Keith Donnell

    Thank you for your reply. We have already played around with quite a few settings (including umbracoContentXMLUseLocalTemp), with no luck. Also, this particular setting has more to do with load balancing (which we don't have configured) than anything else, so it doesn't really apply in our scenario.

  • Keith Donnell 81 posts 186 karma points
    Oct 13, 2017 @ 14:20
    Keith Donnell

    For further reference, I have opened a bug report (which has already been closed as a configuration problem):

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