How to detect if PHP JIT is enabled

Question

What is the simplest way to detect if PHP is compiled with JIT and JIT is enabled from the running script?

so you want a way to check in your script if it's been compiled or interpreted? — Berto99, Jun 30 '20 at 09:37

maio290 · Accepted Answer · 2020-06-30T12:22:31.783

5

You can query the opcache settings directly by calling opcache_get_status():

opcache_get_status()["jit"]["enabled"];

or perform a lookup in the php.ini:

ini_get("opcache.jit")

which is an integer (returned as string) where the last digit states the status of the JIT:

0 - don't JIT
1 - minimal JIT (call standard VM handlers)
2 - selective VM handler inlining
3 - optimized JIT based on static type inference of individual function
4 - optimized JIT based on static type inference and call tree
5 - optimized JIT based on static type inference and inner procedure analyses

Source: https://wiki.php.net/rfc/jit#phpini_defaults

edited Jun 30 '20 at 12:22

answered Jun 30 '20 at 09:39

maio290

5,118
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It seems it does not work - `var_dump(ini_get("opcache.jit"));` returns `string(4) "1205"` for with JIT and without JIT, tested using https://3v4l.org/Q366F – mvorisek Jun 30 '20 at 12:01
@mvorisek I've updated my answer. I guess the opcache_get_status() function is what you were looking for. – maio290 Jun 30 '20 at 12:23
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Thanks, the following works: `opcache_get_status()["jit"]['enabled'] ?? false` – mvorisek Jun 30 '20 at 12:32

score 1 · Answer 2 · answered Oct 07 '20 at 22:38

opcache_get_status() will not work when JIT is disabled and will throw Fatal error.

echo (function_exists('opcache_get_status') 
      && opcache_get_status()['jit']['enabled']) ? 'JIT enabled' : 'JIT disabled';

We must have following settings for JIT in php.ini file.

zend_extension=opcache.so
opcache.enable=1
opcache.enable_cli=1 //optional, for CLI interpreter
opcache.jit_buffer_size=32M //default is 0, with value 0 JIT doesn't work
opcache.jit=1235 //optional, default is "tracing" which is equal to 1254

score 1 · Answer 3 · answered Jan 08 '21 at 16:07

1

php -i | grep "opcache"

checking:
opcache.enable => On => On
opcache.enable_cli => On => On
opcache.jit => tracing => tracing

answered Jan 08 '21 at 16:07

Leo Yuee

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Please update your answer with some details about your code and how does it answers the question. – Cosmin Staicu Jan 08 '21 at 17:48

How to detect if PHP JIT is enabled

3 Answers3