Parser(multiprocessing.Process):
    def __init__(self, jobs, results, quit):
        self.jobs = jobs
        self.results = results
        self.quit = quit
        multiprocessing.Process.__init__(self)

    def run(self):
        pending = []
        while True:
            try:
                self.quit.get_nowait()
            except queue.Empty:
                pass
            else:
                self.results.cancel_join_thread()
                break

            if pending:
                result = pending.pop()
            else:
                try:
                    job = self.jobs.pop()
                except IndexError:
                    break
                result = self.parse(*job)
            try:
                self.results.put(result, timeout=0.25)
            except queue.Full:
                pending.append(result)

    def parse(self, args):
        [actual parsing]

class CookerParser(object):
    def __init__(self, args):

        self.current = 0

        self.toparse = XXX
        self.progress_chunk = int(max(self.toparse / 100, 1))

        self.num_processes = min(multiprocessing.cpu_count(), self.toparse)

        self.haveshutdown = False

        self.results = self.load_cached()
        self.processes = []
        if self.toparse:
            self.parser_quit = multiprocessing.Queue(maxsize=self.num_processes)
            self.result_queue = multiprocessing.Queue()

            def chunkify(lst,n):
                return [lst[i::n] for i in range(n)]
            self.jobs = chunkify(list(self.willparse), self.num_processes)

            for i in range(0, self.num_processes):
                parser = Parser(self.jobs[i], self.result_queue, self.parser_quit)
                parser.start()
                self.processes.append(parser)

            self.results = itertools.chain(self.results, self.parse_generator())

    def shutdown(self, clean=True, force=False):
        if not self.toparse:
            return
        if self.haveshutdown:
            return
        self.haveshutdown = True

        if clean:
            event = bb.event.ParseCompleted(self.cached, self.parsed,
                                            self.skipped, self.masked,
                                            self.virtuals, self.error,
                                            self.total)

            bb.event.fire(event, self.cfgdata)

        # Allow data left in the cancel queue to be discarded
        self.parser_quit.cancel_join_thread()
        for process in self.processes:
            self.parser_quit.put(None)

        # Cleanup the queue before call process.join(), otherwise there might be
        # deadlocks.
        while True:
            try:
               self.result_queue.get(timeout=0.25)
            except queue.Empty:
                break

        for process in self.processes:
            if force:
                process.join(.1)
                process.terminate()
            else:
                process.join()

        self.parser_quit.close()
        self.parser_quit.join_thread()


    def parse_generator(self):
        while True:
            if self.parsed >= self.toparse:
                break

            try:
                result = self.result_queue.get(timeout=0.25)
            except queue.Empty:
                pass
            else:
                value = result[1]
                if isinstance(value, BaseException):
                    raise value
                else:
                    yield result

    def parse_next(self):
        result = []
        parsed = None
        try:
            parsed, mc, result = next(self.results)
        except StopIteration:
            self.shutdown()
            return False
        except bb.BBHandledException as exc:
            self.shutdown(clean=False)
            return False
        [handle result]