1. A method of operating a multicore processor system, said multicore processor system executing multiple different program threads at the same time using respective processor cores for each thread, a first program thread being executed by a first processor core having an exception handling routine, said first program thread including a debug instruction, said debug instruction providing a breakpoint, said method comprising the steps of: providing an assignment matrix identifying at least one additional processor core where execution of one of the program threads by the additional processor core is to be interrupted by the exception handling routine when the debug instruction interrupts the execution of the first program thread in the first processor core at the breakpoint, interrupting execution of the first program thread by the first processor core when the execution of the first program thread reaches the breakpoint, said first processor core then executing an exception handling routine, and transmitting an inter-processor interrupt to the additional processor core using the exception handling routine, said inter-processor interrupt being configured to interrupt the execution of a program thread by the additional processor core.