Clear OPcache and realpath cache on PHP-FPM reload

Hi,

This question is about PHP-FPM.

Is a graceful reload (SIGUSR2) a reliable way to clear OPcache and the 
realpath cache?

Currently, I restart PHP-FPM pools to clear OPcache and realpath cache 
when `opcache.validate_timestamps = Off`. This causes 503s for users. 
I'd like to queue waiting requests instead by using SIGUSR2, which does 
a graceful reload.

I've found that sending SIGUSR2 to the master process clears OPcache. 
php-fpm(8) says:

```
SIGUSR2
     graceful reload of all workers + reload of fpm conf/binary
```

Technically, OPcache is held in the master process. So does 'graceful 
reload of all workers' also mean the master process?

-- 
With kind regards,

William Edwards