> Well that is rather obvious. I doubt PHP has RTOS type guarantees built in.
It's not multithreaded by default (as long as you're not running it in an environment like Apache), no async stuff going on, so the major roadblocks for real-time guarantees are already out of the picture.
The things I would be worried about is garbage collection and array handling. The former should be able to be configured (or in the worst case, rewritten) in a way that provides upper bounds on performance, people have already managed to do that for Java, the latter should be manageable by enforcing boundaries in the user code (e.g. disallow stuff like $foo[]='bar' that dynamically extends the length of an array).
It's not multithreaded by default (as long as you're not running it in an environment like Apache), no async stuff going on, so the major roadblocks for real-time guarantees are already out of the picture.
The things I would be worried about is garbage collection and array handling. The former should be able to be configured (or in the worst case, rewritten) in a way that provides upper bounds on performance, people have already managed to do that for Java, the latter should be manageable by enforcing boundaries in the user code (e.g. disallow stuff like $foo[]='bar' that dynamically extends the length of an array).