Errors in the Apache error log

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    Issues

    I see errors in the Apache error log.  What do they mean?

    Resolution

    If your site is slow or seems to be having trouble serving pages, search your error logs for error messages. To check to see if you are having capacity problems at the moment, you can examine the current error.log.

    Errors

    A number of messages can appear in the error log, indicating different issues.

    In most cases, errors should be fixed as soon as possible.

    • [error] File does not exist: /var/www/html/sitename/docroot/favicon.ico

      This error has minimal impact, but does generate a message in your log for every page visited on your site.

      You can fix this either by adding a favicon.ico file to your docroot, or by using another method to handle 404s. Browsers themselves create a call to the favicon.ico file in the domain root, typically to have a display adjacent to the page title in the browser tab, which is why you might see requests for favicon.ico even when not explicitly referenced in code.

    Warnings

    You should fix warnings whenever possible.

    • [client 10.10.10.10] mod_fcgid: can't apply process slot for /var/www/html/test/docroot/index.php

      This warning is serious, and you should rectify it as quickly as possible. This issue is commonly referred to as skip-spawning or request queueing. This occurs when a request bypasses caching and hits a web server when there are no available PHP processes to handle it. This results in the request getting queued, which means that pages may be slow to load or eventually time out, resulting in a Temporarily Unavailable error on the site and HTTP 503 errors in your request logs.

      If you're using PHP with php-fpm (Acquia Cloud customers are all using PHP-FPM), you'll want to search your fpm-error.log files for pm.max_children to find "skip spawns."

      You can address this type of issue in a number of ways. Streamlining code and reducing the amount of data loading on a page will allow page requests to complete faster, reducing the likelihood of requests backing up. You can also attempt to increase the amount of caching on your site, which offloads requests to your load balancers instead of your web servers. If your global PHP memory limit is higher than 128M and/or your site requires more than 128M to load pages, you can work to reduce the amount of memory required by your site to load some or all pages. If this is possible, reducing your PHP memory limit could allow your server to support more PHP processes. Finally, if none of the preceding solutions are sufficient or possible, you can upsize your server(s) to gain additional memory and more PHP processes.

    • Warning: include_once() [function.include-once]: Unable to allocate memory for pool.

      You can read more about this error at Understanding and Resolving PHP OPcache and OPcache Interned Strings buffer errors.

    Notices

    • NOTICE: [pool sitename] child 12345 startedNOTICE: [pool sitename] child 12345 exited with code 0 after 420.504615 seconds from start

      This notice indicates that a PHP process was idle and the server stopped it to reclaim resources. This is normal, expected behavior and does not require a fix.

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