Cache processes are overloading our server

woodblockprints.org - CA is repeatedly bringing our server to a virtual halt - I suspect this was an issue on our previous host as well. This is from scalahosting support:

There were many PHP-fpm processes again related to "woodbloc". I have killed them and the load is normal, but after a few minutes, these processes are starting again. This isn't normal behavior for sure. However, the issue seems to be related to "/home/woodbloc/public_html/app/tmp/lyon_collectionCache/".

What to do???

Comments

  • It's probably the file cache filling up. We use Stash, a caching library that supports several back-end storage schemes. By default files on disk are used for the cache. This is always available, but on some systems files aren't always cleaned up properly and you can get long delays with high CPU which the cache purges itself.

    Two quick solutions to this problem:

    1. Use an alternate caching storage back-end. REDIS is the best choice, but is not always available. It's packaged for many Linux distributions, including RedHat/CentOS and Ubuntu so it's usually possible to get it installed. REDIS performs well and doesn't use tons of CPU when it fills. Another alternative is SQLLite, which is usually available but performance on may platforms is not wonderful.
    2. Run a cron script perodically to clear out the app/tmp directory where cache files are stored. Clearing the directory will log out all users, so if you go this route try to run it after hours.

    Longer term, we'd have to look at the server environment to figure out why it's not purging itself normally/gradually.


    seth

  • Host writes:

    “REDIS is supported and we can install it right away. Let me know if you want to do that.”

    I said yes.

    now what? Is that “it”? Or is there something else to do or set up?

  • You need to do three things:

    1. Install redis
    2. Install the PHP-Redis extension
    3. Change the __CA_CACHE_BACKEND__ value in setup.php to "redis"
  • edited February 23

    I Changed the CA_CACHE_BACKEND value in /setup.php to "redis" and did the same in /ca/setup.php

    public site (Pawtucket) now returns blank page and

    the admin site (Providence) now returns:

    Fatal error: Uncaught Stash\Exception\RuntimeException: Stash\Driver\Redis is not available...

  • Never mind... Host had installed Redis for the wrong PHP... It's running again - I'll let you know whether we continue to have performance issues with the VPS due to CA caching...

  • Server load has been normal for hours now. Woodblockprints.org site response is blisteringly fast compared to previous host. I'm thrilled. I think redis has solved the caching issue, Seth, thank you!

  • Seth - do we need to keep the cron job you set up that runs every day at midnight:

    /bin/rm -rf /home/woodbloc/public_html/app/tmp/*

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