test_multiprocessing.py 文件源码

def test_pool_worker_lifetime(self):
        p = multiprocessing.Pool(3, maxtasksperchild=10)
        self.assertEqual(3, len(p._pool))
        origworkerpids = [w.pid for w in p._pool]
        # Run many tasks so each worker gets replaced (hopefully)
        results = []
        for i in range(100):
            results.append(p.apply_async(sqr, (i, )))
        # Fetch the results and verify we got the right answers,
        # also ensuring all the tasks have completed.
        for (j, res) in enumerate(results):
            self.assertEqual(res.get(), sqr(j))
        # Refill the pool
        p._repopulate_pool()
        # Wait until all workers are alive
        # (countdown * DELTA = 5 seconds max startup process time)
        countdown = 50
        while countdown and not all(w.is_alive() for w in p._pool):
            countdown -= 1
            time.sleep(DELTA)
        finalworkerpids = [w.pid for w in p._pool]
        # All pids should be assigned.  See issue #7805.
        self.assertNotIn(None, origworkerpids)
        self.assertNotIn(None, finalworkerpids)
        # Finally, check that the worker pids have changed
        self.assertNotEqual(sorted(origworkerpids), sorted(finalworkerpids))
        p.close()
        p.join()