Php, isn't really made for multithread but do you have any workarround to deal with threads in php.
Check the PCNTL library. It may help you to emulate some thread behavior.
Also there's this class:
"This class can emulate the execution of program threads using separate HTTP requests to the same script.
It establishes an HTTP connection to the same Web server to execute the same PHP script. It sends a request passing the name a function to execute and an argument to be passed to that function.
The requested script executes some code that detects the thread execution request and calls the specified function.
When the thread request script ends, the return values of the called function is returned as a serialized string.
The calling script can execute other tasks while the thread script runs. The results may be collected later when the thread script ends."
You can also use processes instead of threads using pipes or sockets to communicate them.