unlikelysource.com

Open a terminal window on your host
Change to the directory that contains the source code for the book:
```
cd /path/to/repo
```
Start the Docker containers running:
- Windows: init up
- Linux/Mac: ./init.sh up
For this demo, shell into the PHP 8 container:
- Windows: init shell 8
- Linux/Mac: ./init.sh shell 8
Inside the container, change to the directory mapped to the source code:
```
cd /repo
```
First make sure OpCache is enabled:
```
cat /etc/php.ini |grep opcache |less
```
Have a look at a little program that resets the settings:
```
less ch10/php8_jit_reset.php
```

To start turn off JIT:

php ch10/php8_jit_reset.php off
cat /etc/php.ini |grep op_cache

Have a look at the test code:
```
less ch10/php8_jit_mandelbrot.php
```
Now run it without JIT. From the browser on your host computer, go to this URL: http://localhost:8888/ch10/php8_jit_mandelbrot.php
Return to the PHP 8 shell and try the outmoded JIT function setting:
```
php ch10/php8_jit_reset.php function
```
Now run it with JIT in function mode. From the browser on your host computer, go to this URL: http://localhost:8888/ch10/php8_jit_mandelbrot.php
Now try the new recommended JIT "tracing" setting. From the PHP shell:
```
php ch10/php8_jit_reset.php tracing
```
Now run it with JIT in function mode. From the browser on your host computer, go to this URL: http://localhost:8888/ch10/php8_jit_mandelbrot.php
Done!

Notes

Starting with PHP version 8.0.1, JIT is disabled if any extension is enabled that uses the internal zend_execute_ex(). This includes Xdebug. Accordingly, the php8_jit_reset.php program disables the Xdebug extension. If you run php8_jit_reset.php off, JIT is disabled, and the Xdebug extension is re-enabled.
For more information see: https://bugs.php.net/bug.php?id=80608.
The source code associated with the book can be found here: https://github.com/PacktPublishing/PHP-8-Programming-Tips-Tricks-and-Best-Practices
Click here to watch the video on YouTube