I´m getting hundreds of these errors in the Apache log in a website with around 4000 visits per hour. I have never seen any evidence of these errors affecting user experience in the website, but i believe it may be happening 1 in 100 requests or something like that, making it very difficult to diagnose.

These messages are really absurd as for what they say they should be killing the requests generating bad user experience, and DRUPAL_ROOT is defined in index.php, so how can it already be defined if it is called only once in the execution thread?

I've seen these errors are almost always close to a Core Dump error record. Any complete theories about what could be happening here?

And drupal_bootstrap not defined right after "require_once DRUPAL_ROOT . '/includes/bootstrap.inc';" how is this possible?

Have anyone seen this happen before?

These are the errors I see in the log:

PHP Notice: Constant DRUPAL_ROOT already defined in /var/www/vhosts/hsbnoticias/index.php on line 17, referer: http://diariodelsur.com.co/noticias/judicial

PHP Fatal error:  Call to undefined function drupal_bootstrap() in /var/www/vhosts/hsbnoticias/index.php on line 20, referer: http://diariodelsur.com.co/noticias/judicial

I´m using a 6GB Linode Ubuntu LAMP Single Server, with around 300 to 400 Apache preforked processes. The website seems to be working fine, so no errors are being reported by visitors, no evidence of errors in analytics, and haven´t seen these popping up in the client side my self.

Update 1: The core dumps don´t reveal any valuable detail, except for: "ProblemType: Crash" and these lines in apport.log:

ERROR: apport (pid 2441) Mon Oct 26 09:31:15 2015: called for pid 2326, signal 11, core limit 0
ERROR: apport (pid 2441) Mon Oct 26 09:31:15 2015: executable: /usr/sbin/apache2 (command line "/usr/sbin/apache2 -k start")
ERROR: apport (pid 2441) Mon Oct 26 09:31:15 2015: is_closing_session(): no DBUS_SESSION_BUS_ADDRESS in environment

Here is the Drupal index.php for reference: http://cgit.drupalcode.org/drupal/tree/index.php?h=7.x

  • "Linde": Did you mean Linode? (WHOIS information for the IP address of diariodelsur.com.co indicates that you're indeed on Linode.) 6 GB is a really big instance (likely an older one as 6 GB instances are no longer available) so I'm surprised you're running out of memory. This is really odd...
    – bwDraco
    Commented Oct 26, 2015 at 7:55
  • If your OOM errors are not caused by a more serious problem such as a bug in your setup and you can afford some downtime, it's likely you'll benefit from upgrading to a modern (SSD-based) 8 GB or 16 GB instance. 6 GB instances (and other oddly-sized instances smaller than 32 GB) are legacy Linodes and you stand to gain a significant amount of performance and resources by upgrading.
    – bwDraco
    Commented Oct 26, 2015 at 8:14


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