Demonstrates a way to run blocking functions which require Ctrl-C handling capability on the main thread via queues from other threads in Python

so9269338.py

from Queue import Queue, Empty
from functools import wraps
from threading import Thread, Semaphore

ctrlc_queue = Queue()
exit_sem = Semaphore(0) # Read: there are 0 ctrlc threads on start-up

def needs_ctrlc(fun):
    @wraps(fun)
    def wrapped(*args, **kwargs):
        result_queue = Queue()
        ctrlc_queue.put((fun, args, kwargs, result_queue))
        result, exception = result_queue.get()
        if exception:
            raise exception
        return result
    return wrapped

@needs_ctrlc
def process_input(threadno):
        print raw_input("[%d] Write something: " % threadno)

def thread_loop(threadno):
    exit_sem.release() # Read: add 1 to number of ctrlc threads
    try:
        for _ in xrange(5):
            process_input(threadno)
        pass
    except KeyboardInterrupt:
        pass
        print "[%d] Caught KeyboardInterrupt, exiting thread" % threadno
    else:
        print "[%d] Finished input, exiting thread" % threadno
    finally:
        exit_sem.acquire() # Read: subtract 1 from number of ctrlc threads
        pass

def ctrlc_threads_exist():
    """As soon as exit_sem.acquire() blocks, we know there are no mor threads"""
    ctrlc_threads_exist = exit_sem.acquire(False)
    if ctrlc_threads_exist:
        exit_sem.release()
    return ctrlc_threads_exist

if __name__ == '__main__':
    for i in xrange(5):
        Thread(target=thread_loop, args=(i,)).start()
    # you *may* need to sleep a millisecond or two here
    while ctrlc_threads_exist():
        try:
            fun, args, kwargs, result_queue = ctrlc_queue.get(timeout=1)
        except Empty:
            continue # must check exit_event regularly
        except KeyboardInterrupt:
            continue # unintentional Ctrl-C during Queue.get
        try:
            result = fun(*args, **kwargs)
        except BaseException, e:
            result_queue.put((None, e))
        else:
            result_queue.put((result, None))