When does PHP's opcache re-parse a file?

Question

Just what the subject says - when does PHP's opcache re-parse a file? Is it based on file timestamp, or file hash or what?

Edit: If my question is not clear then I'll try again:) Say a file "xyz.php" is already in OPCache. Now I modify the file - and it obviously has to be parsed again and updated in the cache. How PHP knows it should do it?

Answer 1

It is based on your opcache configuration in your php.ini file.

opcache.revalidate_freq - Basically put, how often (in seconds) should the code cache expire and check if your code has changed. 0 means it checks your PHP code every single request (which adds lots of stat syscalls). Set it to 0 in your development environment. Production doesn't matter because of the next setting.

opcache.validate_timestamps - When this is enabled, PHP will check the file timestamp per your opcache.revalidate_freq value.

When it's disabled, opcache.revaliate_freq is ignored and PHP files are NEVER checked for updated code. So, if you modify your code, the changes won't actually run until you restart or reload PHP.