Problem

PHP 8.3 on an OpenLiteSpeed server had JIT configured correctly, but the runtime reported:

JIT = Disabled
opcache.jit = tracing
opcac
he.jit_buffer_size = 16M

Environment

  • Debian 13
  • OpenLiteSpeed 1.9.2
  • LSPHP 8.3.33
  • OPcache
  • ionCube Loader 15.5.1

Investigation

I reproduced the environment and verified the actual web PHP configuration, rather than relying on the CLI configuration.

With ionCube loaded:

JIT = Disabled
enabled = false
on = false

I then isolated the loaded ionCube extension by disabling its .ini file and restarting the LSPHP workers.

Resolution

After disabling ionCube:

JIT = On
enabled = true
on = true

Result

The A/B test showed:

ionCube enabled  → JIT disabled
ionCube disabled → JIT enabled

This confirmed an ionCube/JIT compatibility conflict in this PHP 8.3 environment.

What this demonstrated

The investigation involved configuration discovery, runtime verification, extension isolation, process management, and controlled root-cause testing.