Optimal PHP OPCache for Magento 2

opcache-m2-magento.sh

# Since Magento 2 has even 2x the stack traces, means more OP code to cache in memory and avoid
# disk I/O scans with autoloaders without classmapping.

### TOOL
# Identify number of possible PHP files to consider
# view/manage OPcache in a single PHP file
`wget https://github.com/rlerdorf/opcache-status/raw/master/opcache.php`

#  estimate number of max files to run at root of magento
`find . -type f -print | xargs grep "<?php" | wc -l`

# output returned from the command above, should set max_accelerated_files 
# with padding (example: 60k php files found, +5-10k for a buffer)
# note: 65406 
`opcache.max_accelerated_files=65406`

*Production ini*
```
[opcache]
opcache.validate_timestamps=0
opcache.revalidate_freq=0
opcache.max_accelerated_files=65536
opcache.memory_consumption=192
opcache.interned_strings_buffer=16
opcache.fast_shutdown=1
```

*Development/Local ini*
```
[opcache]
opcache.validate_timestamps=1
opcache.max_accelerated_files=65536 
opcache.memory_consumption=192
opcache.interned_strings_buffer=16
opcache.fast_shutdown=1
```

references

* https://www.scalingphpbook.com/blog/2014/02/14/best-zend-opcache-settings.html
* https://magento.stackexchange.com/questions/95058/opcache-recommended-configuration-for-magento2
* http://devdocs.magento.com/guides/v2.1/install-gde/prereq/php-settings.html