Python thread.start() Examples

def test_reinit_tls_after_fork(self):
        # Issue #13817: fork() would deadlock in a multithreaded program with
        # the ad-hoc TLS implementation.

        def do_fork_and_wait():
            # just fork a child process and wait it
            pid = os.fork()
            if pid > 0:
                os.waitpid(pid, 0)
            else:
                os._exit(0)

        # start a bunch of threads that will fork() child processes
        threads = []
        for i in range(16):
            t = threading.Thread(target=do_fork_and_wait)
            threads.append(t)
            t.start()

        for t in threads:
            t.join() 

def background_command(command, require_zero_status=False):
    """Executes a command in a separate thread, like running with '&' in the shell.
       If you want the program to die if the command eventually returns with
       nonzero status, then set require_zero_status to True.  'command' will be
       executed in 'shell' mode, so it's OK for it to contain pipes and other
       shell constructs.

       This function returns the Thread object created, just in case you want
       to wait for that specific command to finish.  For example, you could do:
             thread = background_command('foo | bar')
             # do something else while waiting for it to finish
             thread.join()

       See also:
         - wait_for_background_commands(), which can be used
           at the end of the program to wait for all these commands to terminate.
         - execute_command() and get_command_stdout(), which allow you to
           execute commands in the foreground.
    """

    p = subprocess.Popen(command, shell=True)
    thread = threading.Thread(target=background_command_waiter, args=(command, p, require_zero_status))
    thread.daemon = True  # make sure it exits if main thread is terminated abnormally.
    thread.start()
    return thread 

def test_3_join_in_forked_from_thread(self):
        # Like the test above, but fork() was called from a worker thread
        # In the forked process, the main Thread object must be marked as stopped.
        script = """if 1:
            main_thread = threading.current_thread()
            def worker():
                childpid = os.fork()
                if childpid != 0:
                    os.waitpid(childpid, 0)
                    sys.exit(0)

                t = threading.Thread(target=joiningfunc,
                                     args=(main_thread,))
                print 'end of main'
                t.start()
                t.join() # Should not block: main_thread is already stopped

            w = threading.Thread(target=worker)
            w.start()
            """
        self._run_and_join(script) 

def test_join_nondaemon_on_shutdown(self):
        # Issue 1722344
        # Raising SystemExit skipped threading._shutdown
        p = subprocess.Popen([sys.executable, "-c", """if 1:
                import threading
                from time import sleep

                def child():
                    sleep(1)
                    # As a non-daemon thread we SHOULD wake up and nothing
                    # should be torn down yet
                    print "Woke up, sleep function is:", sleep

                threading.Thread(target=child).start()
                raise SystemExit
            """],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        stdout, stderr = p.communicate()
        self.assertEqual(stdout.strip(),
            "Woke up, sleep function is: <built-in function sleep>")
        stderr = re.sub(r"^\[\d+ refs\]", "", stderr, re.MULTILINE).strip()
        self.assertEqual(stderr, "") 

def test_3_join_in_forked_from_thread(self):
        # Like the test above, but fork() was called from a worker thread
        # In the forked process, the main Thread object must be marked as stopped.
        script = """if 1:
            main_thread = threading.current_thread()
            def worker():
                childpid = os.fork()
                if childpid != 0:
                    os.waitpid(childpid, 0)
                    sys.exit(0)

                t = threading.Thread(target=joiningfunc,
                                     args=(main_thread,))
                print 'end of main'
                t.start()
                t.join() # Should not block: main_thread is already stopped

            w = threading.Thread(target=worker)
            w.start()
            """
        self._run_and_join(script) 

def test_enumerate_after_join(self):
        # Try hard to trigger #1703448: a thread is still returned in
        # threading.enumerate() after it has been join()ed.
        enum = threading.enumerate
        old_interval = sys.getcheckinterval()
        try:
            for i in xrange(1, 100):
                # Try a couple times at each thread-switching interval
                # to get more interleavings.
                sys.setcheckinterval(i // 5)
                t = threading.Thread(target=lambda: None)
                t.start()
                t.join()
                l = enum()
                self.assertNotIn(t, l,
                    "#1703448 triggered after %d trials: %s" % (i, l))
        finally:
            sys.setcheckinterval(old_interval) 

def test_join_nondaemon_on_shutdown(self):
        # Issue 1722344
        # Raising SystemExit skipped threading._shutdown
        p = subprocess.Popen([sys.executable, "-c", """if 1:
                import threading
                from time import sleep

                def child():
                    sleep(1)
                    # As a non-daemon thread we SHOULD wake up and nothing
                    # should be torn down yet
                    print "Woke up, sleep function is:", sleep

                threading.Thread(target=child).start()
                raise SystemExit
            """],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        stdout, stderr = p.communicate()
        self.assertEqual(stdout.strip(),
            "Woke up, sleep function is: <built-in function sleep>")
        stderr = re.sub(r"^\[\d+ refs\]", "", stderr, re.MULTILINE).strip()
        self.assertEqual(stderr, "") 

def test_is_alive_after_fork(self):
        # Try hard to trigger #18418: is_alive() could sometimes be True on
        # threads that vanished after a fork.
        old_interval = sys.getcheckinterval()

        # Make the bug more likely to manifest.
        sys.setcheckinterval(10)

        try:
            for i in range(20):
                t = threading.Thread(target=lambda: None)
                t.start()
                pid = os.fork()
                if pid == 0:
                    os._exit(1 if t.is_alive() else 0)
                else:
                    t.join()
                    pid, status = os.waitpid(pid, 0)
                    self.assertEqual(0, status)
        finally:
            sys.setcheckinterval(old_interval) 

def test_BoundedSemaphore_limit(self):
        # BoundedSemaphore should raise ValueError if released too often.
        for limit in range(1, 10):
            bs = threading.BoundedSemaphore(limit)
            threads = [threading.Thread(target=bs.acquire)
                       for _ in range(limit)]
            for t in threads:
                t.start()
            for t in threads:
                t.join()
            threads = [threading.Thread(target=bs.release)
                       for _ in range(limit)]
            for t in threads:
                t.start()
            for t in threads:
                t.join()
            self.assertRaises(ValueError, bs.release) 

def test_join_nondaemon_on_shutdown(self):
        # Issue 1722344
        # Raising SystemExit skipped threading._shutdown
        p = subprocess.Popen([sys.executable, "-c", """if 1:
                import threading
                from time import sleep

                def child():
                    sleep(1)
                    # As a non-daemon thread we SHOULD wake up and nothing
                    # should be torn down yet
                    print "Woke up, sleep function is:", sleep

                threading.Thread(target=child).start()
                raise SystemExit
            """],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        stdout, stderr = p.communicate()
        self.assertTrue(stdout.strip().startswith(
            "Woke up, sleep function is: <java function sleep"))
        stderr = re.sub(r"^\[\d+ refs\]", "", stderr, re.MULTILINE).strip()
        self.assertEqual(stderr, "") 

def test_print_exception(self):
        script = r"""if 1:
            import threading
            import time

            running = False
            def run():
                global running
                running = True
                while running:
                    time.sleep(0.01)
                1.0/0.0
            t = threading.Thread(target=run)
            t.start()
            while not running:
                time.sleep(0.01)
            running = False
            t.join()
            """
        rc, out, err = assert_python_ok("-c", script)
        self.assertEqual(out, '')
        self.assertIn("Exception in thread", err)
        self.assertIn("Traceback (most recent call last):", err)
        self.assertIn("ZeroDivisionError", err)
        self.assertNotIn("Unhandled exception", err) 

def test_enumerate_after_join(self):
        # Try hard to trigger #1703448: a thread is still returned in
        # threading.enumerate() after it has been join()ed.
        enum = threading.enumerate
        old_interval = sys.getcheckinterval()
        try:
            for i in xrange(1, 100):
                # Try a couple times at each thread-switching interval
                # to get more interleavings.
                sys.setcheckinterval(i // 5)
                t = threading.Thread(target=lambda: None)
                t.start()
                t.join()
                l = enum()
                self.assertNotIn(t, l,
                    "#1703448 triggered after %d trials: %s" % (i, l))
        finally:
            sys.setcheckinterval(old_interval) 

def test_enumerate_after_join(self):
        # Try hard to trigger #1703448: a thread is still returned in
        # threading.enumerate() after it has been join()ed.
        enum = threading.enumerate
        old_interval = sys.getcheckinterval()
        try:
            for i in xrange(1, 100):
                # Try a couple times at each thread-switching interval
                # to get more interleavings.
                sys.setcheckinterval(i // 5)
                t = threading.Thread(target=lambda: None)
                t.start()
                t.join()
                l = enum()
                self.assertNotIn(t, l,
                    "#1703448 triggered after %d trials: %s" % (i, l))
        finally:
            sys.setcheckinterval(old_interval) 

def test_enumerate_after_join(self):
        # Try hard to trigger #1703448: a thread is still returned in
        # threading.enumerate() after it has been join()ed.
        enum = threading.enumerate
        old_interval = sys.getcheckinterval()
        try:
            for i in xrange(1, 100):
                # Try a couple times at each thread-switching interval
                # to get more interleavings.
                sys.setcheckinterval(i // 5)
                t = threading.Thread(target=lambda: None)
                t.start()
                t.join()
                l = enum()
                self.assertNotIn(t, l,
                    "#1703448 triggered after %d trials: %s" % (i, l))
        finally:
            sys.setcheckinterval(old_interval) 

def test_3_join_in_forked_from_thread(self):
        # Like the test above, but fork() was called from a worker thread
        # In the forked process, the main Thread object must be marked as stopped.
        script = """if 1:
            main_thread = threading.current_thread()
            def worker():
                childpid = os.fork()
                if childpid != 0:
                    os.waitpid(childpid, 0)
                    sys.exit(0)

                t = threading.Thread(target=joiningfunc,
                                     args=(main_thread,))
                print 'end of main'
                t.start()
                t.join() # Should not block: main_thread is already stopped

            w = threading.Thread(target=worker)
            w.start()
            """
        self._run_and_join(script) 

def test_reinit_tls_after_fork(self):
        # Issue #13817: fork() would deadlock in a multithreaded program with
        # the ad-hoc TLS implementation.

        def do_fork_and_wait():
            # just fork a child process and wait it
            pid = os.fork()
            if pid > 0:
                os.waitpid(pid, 0)
            else:
                os._exit(0)

        # start a bunch of threads that will fork() child processes
        threads = []
        for i in range(16):
            t = threading.Thread(target=do_fork_and_wait)
            threads.append(t)
            t.start()

        for t in threads:
            t.join() 

def test_join_nondaemon_on_shutdown(self):
        # Issue 1722344
        # Raising SystemExit skipped threading._shutdown
        p = subprocess.Popen([sys.executable, "-c", """if 1:
                import threading
                from time import sleep

                def child():
                    sleep(1)
                    # As a non-daemon thread we SHOULD wake up and nothing
                    # should be torn down yet
                    print "Woke up, sleep function is:", sleep

                threading.Thread(target=child).start()
                raise SystemExit
            """],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        stdout, stderr = p.communicate()
        self.assertTrue(stdout.strip().startswith(
            "Woke up, sleep function is: <java function sleep"))
        stderr = re.sub(r"^\[\d+ refs\]", "", stderr, re.MULTILINE).strip()
        self.assertEqual(stderr, "") 

def test_join_nondaemon_on_shutdown(self):
        # Issue 1722344
        # Raising SystemExit skipped threading._shutdown
        p = subprocess.Popen([sys.executable, "-c", """if 1:
                import threading
                from time import sleep

                def child():
                    sleep(1)
                    # As a non-daemon thread we SHOULD wake up and nothing
                    # should be torn down yet
                    print "Woke up, sleep function is:", sleep

                threading.Thread(target=child).start()
                raise SystemExit
            """],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        stdout, stderr = p.communicate()
        self.assertEqual(stdout.strip(),
            "Woke up, sleep function is: <built-in function sleep>")
        stderr = re.sub(r"^\[\d+ refs\]", "", stderr, re.MULTILINE).strip()
        self.assertEqual(stderr, "") 

def test_enumerate_after_join(self):
        # Try hard to trigger #1703448: a thread is still returned in
        # threading.enumerate() after it has been join()ed.
        enum = threading.enumerate
        old_interval = sys.getcheckinterval()
        try:
            for i in xrange(1, 100):
                # Try a couple times at each thread-switching interval
                # to get more interleavings.
                sys.setcheckinterval(i // 5)
                t = threading.Thread(target=lambda: None)
                t.start()
                t.join()
                l = enum()
                self.assertNotIn(t, l,
                    "#1703448 triggered after %d trials: %s" % (i, l))
        finally:
            sys.setcheckinterval(old_interval) 

def test_is_alive_after_fork(self):
        # Try hard to trigger #18418: is_alive() could sometimes be True on
        # threads that vanished after a fork.
        old_interval = sys.getcheckinterval()

        # Make the bug more likely to manifest.
        sys.setcheckinterval(10)

        try:
            for i in range(20):
                t = threading.Thread(target=lambda: None)
                t.start()
                pid = os.fork()
                if pid == 0:
                    os._exit(1 if t.is_alive() else 0)
                else:
                    t.join()
                    pid, status = os.waitpid(pid, 0)
                    self.assertEqual(0, status)
        finally:
            sys.setcheckinterval(old_interval) 

def test_BoundedSemaphore_limit(self):
        # BoundedSemaphore should raise ValueError if released too often.
        for limit in range(1, 10):
            bs = threading.BoundedSemaphore(limit)
            threads = [threading.Thread(target=bs.acquire)
                       for _ in range(limit)]
            for t in threads:
                t.start()
            for t in threads:
                t.join()
            threads = [threading.Thread(target=bs.release)
                       for _ in range(limit)]
            for t in threads:
                t.start()
            for t in threads:
                t.join()
            self.assertRaises(ValueError, bs.release) 

def test_3_join_in_forked_from_thread(self):
        # Like the test above, but fork() was called from a worker thread
        # In the forked process, the main Thread object must be marked as stopped.
        script = """if 1:
            main_thread = threading.current_thread()
            def worker():
                childpid = os.fork()
                if childpid != 0:
                    os.waitpid(childpid, 0)
                    sys.exit(0)

                t = threading.Thread(target=joiningfunc,
                                     args=(main_thread,))
                print 'end of main'
                t.start()
                t.join() # Should not block: main_thread is already stopped

            w = threading.Thread(target=worker)
            w.start()
            """
        self._run_and_join(script) 

def test_reinit_tls_after_fork(self):
        # Issue #13817: fork() would deadlock in a multithreaded program with
        # the ad-hoc TLS implementation.

        def do_fork_and_wait():
            # just fork a child process and wait it
            pid = os.fork()
            if pid > 0:
                os.waitpid(pid, 0)
            else:
                os._exit(0)

        # start a bunch of threads that will fork() child processes
        threads = []
        for i in range(16):
            t = threading.Thread(target=do_fork_and_wait)
            threads.append(t)
            t.start()

        for t in threads:
            t.join() 

def test_reinit_tls_after_fork(self):
        # Issue #13817: fork() would deadlock in a multithreaded program with
        # the ad-hoc TLS implementation.

        def do_fork_and_wait():
            # just fork a child process and wait it
            pid = os.fork()
            if pid > 0:
                os.waitpid(pid, 0)
            else:
                os._exit(0)

        # start a bunch of threads that will fork() child processes
        threads = []
        for i in range(16):
            t = threading.Thread(target=do_fork_and_wait)
            threads.append(t)
            t.start()

        for t in threads:
            t.join() 

def test_print_exception(self):
        script = r"""if 1:
            import threading
            import time

            running = False
            def run():
                global running
                running = True
                while running:
                    time.sleep(0.01)
                1/0
            t = threading.Thread(target=run)
            t.start()
            while not running:
                time.sleep(0.01)
            running = False
            t.join()
            """
        rc, out, err = assert_python_ok("-c", script)
        self.assertEqual(out, '')
        self.assertIn("Exception in thread", err)
        self.assertIn("Traceback (most recent call last):", err)
        self.assertIn("ZeroDivisionError", err)
        self.assertNotIn("Unhandled exception", err) 

def test_3_join_in_forked_from_thread(self):
        # Like the test above, but fork() was called from a worker thread
        # In the forked process, the main Thread object must be marked as stopped.
        script = """if 1:
            main_thread = threading.current_thread()
            def worker():
                childpid = os.fork()
                if childpid != 0:
                    os.waitpid(childpid, 0)
                    sys.exit(0)

                t = threading.Thread(target=joiningfunc,
                                     args=(main_thread,))
                print 'end of main'
                t.start()
                t.join() # Should not block: main_thread is already stopped

            w = threading.Thread(target=worker)
            w.start()
            """
        self._run_and_join(script) 

def test_BoundedSemaphore_limit(self):
        # BoundedSemaphore should raise ValueError if released too often.
        for limit in range(1, 10):
            bs = threading.BoundedSemaphore(limit)
            threads = [threading.Thread(target=bs.acquire)
                       for _ in range(limit)]
            for t in threads:
                t.start()
            for t in threads:
                t.join()
            threads = [threading.Thread(target=bs.release)
                       for _ in range(limit)]
            for t in threads:
                t.start()
            for t in threads:
                t.join()
            self.assertRaises(ValueError, bs.release) 

def test_is_alive_after_fork(self):
        # Try hard to trigger #18418: is_alive() could sometimes be True on
        # threads that vanished after a fork.
        old_interval = sys.getcheckinterval()

        # Make the bug more likely to manifest.
        sys.setcheckinterval(10)

        try:
            for i in range(20):
                t = threading.Thread(target=lambda: None)
                t.start()
                pid = os.fork()
                if pid == 0:
                    os._exit(1 if t.is_alive() else 0)
                else:
                    t.join()
                    pid, status = os.waitpid(pid, 0)
                    self.assertEqual(0, status)
        finally:
            sys.setcheckinterval(old_interval) 

def test_join_nondaemon_on_shutdown(self):
        # Issue 1722344
        # Raising SystemExit skipped threading._shutdown
        p = subprocess.Popen([sys.executable, "-c", """if 1:
                import threading
                from time import sleep

                def child():
                    sleep(1)
                    # As a non-daemon thread we SHOULD wake up and nothing
                    # should be torn down yet
                    print "Woke up, sleep function is:", sleep

                threading.Thread(target=child).start()
                raise SystemExit
            """],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        stdout, stderr = p.communicate()
        self.assertEqual(stdout.strip(),
            "Woke up, sleep function is: <built-in function sleep>")
        stderr = re.sub(r"^\[\d+ refs\]", "", stderr, re.MULTILINE).strip()
        self.assertEqual(stderr, "") 

def test_enumerate_after_join(self):
        # Try hard to trigger #1703448: a thread is still returned in
        # threading.enumerate() after it has been join()ed.
        enum = threading.enumerate
        old_interval = sys.getcheckinterval()
        try:
            for i in xrange(1, 100):
                # Try a couple times at each thread-switching interval
                # to get more interleavings.
                sys.setcheckinterval(i // 5)
                t = threading.Thread(target=lambda: None)
                t.start()
                t.join()
                l = enum()
                self.assertNotIn(t, l,
                    "#1703448 triggered after %d trials: %s" % (i, l))
        finally:
            sys.setcheckinterval(old_interval)