Docker PHP Circular JIT Dependency Dropped

Xdebug v3.0 overrides zend_execute_ex() function call. This causes JIT to be deactivated when Xdebug is on.

Run with Xdebug off

To see that JIT is working, build this repository following these steps, where Xdebug is off:

export ENABLE_XDEBUG=0
docker-compose build
docker-compose up -d
docker-compose exec php composer install

Check Docker logs for PHP container to see that there are no errors:

docker logs php

You will get following output:

[15-Sep-2021 12:00:00] NOTICE: fpm is running, pid 1
[15-Sep-2021 12:00:00] NOTICE: ready to handle connections

Then go to http://127.0.0.1:8080 in your browser and you will see following dump of opcache_get_status() function call:

Everything is working. Both Opcache and JIT are enabled. Now shut down containers:

docker-compose down

Run with Xdebug on

Now, to see that JIT is not working, when Xdebug is on, build this repository following these steps:

export ENABLE_XDEBUG=1
docker-compose build
docker-compose up -d
docker-compose exec php composer install

Check Docker logs for PHP container to see the errors:

docker logs php

You will get following output:

<br />
<b>Warning</b>:  JIT is incompatible with third party extensions that override zend_execute_ex(). JIT disabled. in <b>Unknown</b> on line <b>0</b><br />
[15-Sep-2021 12:00:00] NOTICE: fpm is running, pid 1
[15-Sep-2021 12:00:00] NOTICE: ready to handle connections

Then go to http://127.0.0.1:8080 in your browser and you will see following dump of opcache_get_status() function call:

As you can see, Opcache is enabled, but Xdebug causes JIT to be deactivated. Now shut down containers:

docker-compose down