php - Zend OPCache - opcache.enable_cli 1 or 0? What does it do?

Question

In the documentation it says "mostly used for debugging" which would lead me think "never enable it unless you've a problem and need to do some debugging," however reading mostly everything that I could find about it says to enable it "opcache.enable_cli 1" but why? I could not find any information concerning this matter, so if anybody knows, why should I enable it if the documentation basically says to keep it on 0?

Answer 1

With PHP7 and file-based caching, it can now make sense to enable opcache for CLI. The best possibility would be to have a separate php.ini for CLI with the following configuration:

opcache.enable=1
opcache.enable_cli=1
opcache.file_cache="/tmp/php-file-cache"
opcache.file_cache_only=1
opcache.file_cache_consistency_checks=1

opcache.file_cache_only=1 makes sure that the in-memory opcache is disabled and only files are used, which is what you want for CLI. This should boost execution time by quite a bit.

In the php.ini for FPM, you will want to have the same settings but use opcache.file_cache_only=0, so in-memory opcache is used and the file cache is used as a fallback (which also makes FPM faster, because the file cache reduces warmup time when FPM is restarted or opcache is reset, because the cached files remain).

This way, CLI and FPM share the file cache, and FPM has the in-memory cache as a second primary cache for maximum speed. A great improvement in PHP7! Just make sure to choose a directory for opcache.file_cache that both CLI and FPM can write to, and that the same user does the writing/reading.

UPDATE 2017

I would not recommend to use the file cache with FPM anymore (only use it for CLI), because there is no way to reset the cache when setting opcache.validate_timestamps=0 - the file cache prevents PHP-FPM from recognizing any changes, because opcache_reset() or even a complete PHP-FPM restart does not affect the file cache and there is no equivalent for the file cache, so changed scripts are never noticed. I reported this as a "bug"/"feature request" in March 2016, but this is currently not seen as an issue. Just beware if you use opcache.validate_timestamps=0!