FPM sometimes serving from wrong pool

I am using nginx + php5-fpm with multiple sites & pools.

Every pool in the fpm is chrooted.

Normally everything works as expected. But sometimes (every 1/20th request), especially if I requested Site B before, site A serves the content of site B. I already looked into nginx config, it is always using the correct fpm socket (looked into error/access log). Also every fpm-pool has its own name and socket.

I found this post which describes my problem, but I don't have APC installed...: http://regilero.github.io/Drupal/English/2013/05/16/Warning_chrooted_php_fpm_and_apc/

So does someone have an idea what could be wrong?

Solution 1:

I encountered the same issue on Debian 8, under PHP5-fpm and Apache. My solution was to uncomment or add this line in php.ini:

opcache.enable=0

That seemed to be all. Thank you for comments on the original question that helped me track this down.