Python sys.getcheckinterval() Examples

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_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_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 setUp(self):
        """
        Reduce the CPython check interval so that thread switches happen much
        more often, hopefully exercising more possible race conditions.  Also,
        delay actual test startup until the reactor has been started.
        """
        if hasattr(sys, 'getcheckinterval'):
            self.addCleanup(sys.setcheckinterval, sys.getcheckinterval())
            sys.setcheckinterval(7)
        # XXX This is a trial hack.  We need to make sure the reactor
        # actually *starts* for isInIOThread() to have a meaningful result.
        # Returning a Deferred here should force that to happen, if it has
        # not happened already.  In the future, this should not be
        # necessary.
        d = defer.Deferred()
        reactor.callLater(0, d.callback, None)
        return d 

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()
        sys.setcheckinterval(1)
        try:
            for i in xrange(1, 1000):
                t = threading.Thread(target=lambda: None)
                t.start()
                t.join()
                l = enum()
                self.assertFalse(t in 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_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 collect_in_thread(period=0.001):
    """
    Ensure GC collections happen in a different thread, at a high frequency.
    """
    threading = test_support.import_module('threading')
    please_stop = False

    def collect():
        while not please_stop:
            time.sleep(period)
            gc.collect()

    with test_support.disable_gc():
        old_interval = sys.getcheckinterval()
        sys.setcheckinterval(20)
        t = threading.Thread(target=collect)
        t.start()
        try:
            yield
        finally:
            please_stop = True
            t.join()
            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_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_setcheckinterval(self):
        self.assertRaises(TypeError, sys.setcheckinterval)
        orig = sys.getcheckinterval()
        for n in 0, 100, 120, orig: # orig last to restore starting state
            sys.setcheckinterval(n)
            self.assertEquals(sys.getcheckinterval(), n) 

def test_setcheckinterval(self):
        with warnings.catch_warnings():
            warnings.simplefilter("ignore")
            self.assertRaises(TypeError, sys.setcheckinterval)
            orig = sys.getcheckinterval()
            for n in 0, 100, 120, orig: # orig last to restore starting state
                sys.setcheckinterval(n)
                self.assertEqual(sys.getcheckinterval(), n) 

def setUpClass(self):
            self.checkInterval = sys.getcheckinterval()
            sys.setcheckinterval(7) 

def test_setcheckinterval(self):
        self.assertRaises(TypeError, sys.setcheckinterval)
        orig = sys.getcheckinterval()
        for n in 0, 100, 120, orig: # orig last to restore starting state
            sys.setcheckinterval(n)
            self.assertEquals(sys.getcheckinterval(), n) 

def test_setcheckinterval(self):
        with warnings.catch_warnings():
            warnings.simplefilter("ignore")
            self.assertRaises(TypeError, sys.setcheckinterval)
            orig = sys.getcheckinterval()
            for n in 0, 100, 120, orig: # orig last to restore starting state
                sys.setcheckinterval(n)
                self.assertEqual(sys.getcheckinterval(), n) 

def test_setcheckinterval(self):
        self.assertRaises(TypeError, sys.setcheckinterval)
        orig = sys.getcheckinterval()
        for n in 0, 100, 120, orig: # orig last to restore starting state
            sys.setcheckinterval(n)
            self.assertEquals(sys.getcheckinterval(), n) 

def test_setcheckinterval(self):
        self.assertRaises(TypeError, sys.setcheckinterval)
        orig = sys.getcheckinterval()
        for n in 0, 100, 120, orig: # orig last to restore starting state
            sys.setcheckinterval(n)
            self.assertEqual(sys.getcheckinterval(), n) 

def setUp(self):
        """
        Reduce the CPython check interval so that thread switches happen much
        more often, hopefully exercising more possible race conditions.  Also,
        delay actual test startup until the reactor has been started.
        """
        if _PY3:
            if getattr(sys, 'getswitchinterval', None) is not None:
                self.addCleanup(sys.setswitchinterval, sys.getswitchinterval())
                sys.setswitchinterval(0.0000001)
        else:
            if getattr(sys, 'getcheckinterval', None) is not None:
                self.addCleanup(sys.setcheckinterval, sys.getcheckinterval())
                sys.setcheckinterval(7) 

def test_setcheckinterval(self):
        with warnings.catch_warnings():
            warnings.simplefilter("ignore")
            self.assertRaises(TypeError, sys.setcheckinterval)
            orig = sys.getcheckinterval()
            for n in 0, 100, 120, orig: # orig last to restore starting state
                sys.setcheckinterval(n)
                self.assertEqual(sys.getcheckinterval(), n) 

def setUp(self):
        """
        Reduce the CPython check interval so that thread switches happen much
        more often, hopefully exercising more possible race conditions.  Also,
        delay actual test startup until the reactor has been started.
        """
        if _PY3:
            if getattr(sys, 'getswitchinterval', None) is not None:
                self.addCleanup(sys.setswitchinterval, sys.getswitchinterval())
                sys.setswitchinterval(0.0000001)
        else:
            if getattr(sys, 'getcheckinterval', None) is not None:
                self.addCleanup(sys.setcheckinterval, sys.getcheckinterval())
                sys.setcheckinterval(7) 

def test_setcheckinterval(self):
        self.assertRaises(TypeError, sys.setcheckinterval)
        orig = sys.getcheckinterval()
        for n in 0, 100, 120, orig: # orig last to restore starting state
            sys.setcheckinterval(n)
            self.assertEqual(sys.getcheckinterval(), n) 

def test_setcheckinterval(self):
        self.assertRaises(TypeError, sys.setcheckinterval)
        orig = sys.getcheckinterval()
        for n in 0, 100, 120, orig: # orig last to restore starting state
            sys.setcheckinterval(n)
            self.assertEqual(sys.getcheckinterval(), n) 

def test_setcheckinterval(self):
        self.assertRaises(TypeError, sys.setcheckinterval)
        orig = sys.getcheckinterval()
        for n in 0, 100, 120, orig: # orig last to restore starting state
            sys.setcheckinterval(n)
            self.assertEqual(sys.getcheckinterval(), n) 

def test_trashcan_threads(self):
        # Issue #13992: trashcan mechanism should be thread-safe
        NESTING = 60
        N_THREADS = 2

        def sleeper_gen():
            """A generator that releases the GIL when closed or dealloc'ed."""
            try:
                yield
            finally:
                time.sleep(0.000001)

        class C(list):
            # Appending to a list is atomic, which avoids the use of a lock.
            inits = []
            dels = []
            def __init__(self, alist):
                self[:] = alist
                C.inits.append(None)
            def __del__(self):
                # This __del__ is called by subtype_dealloc().
                C.dels.append(None)
                # `g` will release the GIL when garbage-collected.  This
                # helps assert subtype_dealloc's behaviour when threads
                # switch in the middle of it.
                g = sleeper_gen()
                next(g)
                # Now that __del__ is finished, subtype_dealloc will proceed
                # to call list_dealloc, which also uses the trashcan mechanism.

        def make_nested():
            """Create a sufficiently nested container object so that the
            trashcan mechanism is invoked when deallocating it."""
            x = C([])
            for i in range(NESTING):
                x = [C([x])]
            del x

        def run_thread():
            """Exercise make_nested() in a loop."""
            while not exit:
                make_nested()

        old_checkinterval = sys.getcheckinterval()
        sys.setcheckinterval(3)
        try:
            exit = False
            threads = []
            for i in range(N_THREADS):
                t = threading.Thread(target=run_thread)
                threads.append(t)
            for t in threads:
                t.start()
            time.sleep(1.0)
            exit = True
            for t in threads:
                t.join()
        finally:
            sys.setcheckinterval(old_checkinterval)
        gc.collect()
        self.assertEqual(len(C.inits), len(C.dels)) 

def test_trashcan_threads(self):
        # Issue #13992: trashcan mechanism should be thread-safe
        NESTING = 60
        N_THREADS = 2

        def sleeper_gen():
            """A generator that releases the GIL when closed or dealloc'ed."""
            try:
                yield
            finally:
                time.sleep(0.000001)

        class C(list):
            # Appending to a list is atomic, which avoids the use of a lock.
            inits = []
            dels = []
            def __init__(self, alist):
                self[:] = alist
                C.inits.append(None)
            def __del__(self):
                # This __del__ is called by subtype_dealloc().
                C.dels.append(None)
                # `g` will release the GIL when garbage-collected.  This
                # helps assert subtype_dealloc's behaviour when threads
                # switch in the middle of it.
                g = sleeper_gen()
                next(g)
                # Now that __del__ is finished, subtype_dealloc will proceed
                # to call list_dealloc, which also uses the trashcan mechanism.

        def make_nested():
            """Create a sufficiently nested container object so that the
            trashcan mechanism is invoked when deallocating it."""
            x = C([])
            for i in range(NESTING):
                x = [C([x])]
            del x

        def run_thread():
            """Exercise make_nested() in a loop."""
            while not exit:
                make_nested()

        old_checkinterval = sys.getcheckinterval()
        sys.setcheckinterval(3)
        try:
            exit = False
            threads = []
            for i in range(N_THREADS):
                t = threading.Thread(target=run_thread)
                threads.append(t)
            for t in threads:
                t.start()
            time.sleep(1.0)
            exit = True
            for t in threads:
                t.join()
        finally:
            sys.setcheckinterval(old_checkinterval)
        gc.collect()
        self.assertEqual(len(C.inits), len(C.dels)) 

def test_trashcan_threads(self):
        # Issue #13992: trashcan mechanism should be thread-safe
        NESTING = 60
        N_THREADS = 2

        def sleeper_gen():
            """A generator that releases the GIL when closed or dealloc'ed."""
            try:
                yield
            finally:
                time.sleep(0.000001)

        class C(list):
            # Appending to a list is atomic, which avoids the use of a lock.
            inits = []
            dels = []
            def __init__(self, alist):
                self[:] = alist
                C.inits.append(None)
            def __del__(self):
                # This __del__ is called by subtype_dealloc().
                C.dels.append(None)
                # `g` will release the GIL when garbage-collected.  This
                # helps assert subtype_dealloc's behaviour when threads
                # switch in the middle of it.
                g = sleeper_gen()
                next(g)
                # Now that __del__ is finished, subtype_dealloc will proceed
                # to call list_dealloc, which also uses the trashcan mechanism.

        def make_nested():
            """Create a sufficiently nested container object so that the
            trashcan mechanism is invoked when deallocating it."""
            x = C([])
            for i in range(NESTING):
                x = [C([x])]
            del x

        def run_thread():
            """Exercise make_nested() in a loop."""
            while not exit:
                make_nested()

        old_checkinterval = sys.getcheckinterval()
        sys.setcheckinterval(3)
        try:
            exit = False
            threads = []
            for i in range(N_THREADS):
                t = threading.Thread(target=run_thread)
                threads.append(t)
            for t in threads:
                t.start()
            time.sleep(1.0)
            exit = True
            for t in threads:
                t.join()
        finally:
            sys.setcheckinterval(old_checkinterval)
        gc.collect()
        self.assertEqual(len(C.inits), len(C.dels)) 

def test_trashcan_threads(self):
        # Issue #13992: trashcan mechanism should be thread-safe
        NESTING = 60
        N_THREADS = 2
     
        def sleeper_gen():
            """A generator that releases the GIL when closed or dealloc'ed."""
            try:
                yield
            finally:
                time.sleep(0.000001)
     
        class C(list):
            # Appending to a list is atomic, which avoids the use of a lock.
            inits = []
            dels = []
            def __init__(self, alist):
                self[:] = alist
                C.inits.append(None)
            def __del__(self):
                # This __del__ is called by subtype_dealloc().
                C.dels.append(None)
                # `g` will release the GIL when garbage-collected.  This
                # helps assert subtype_dealloc's behaviour when threads
                # switch in the middle of it.
                g = sleeper_gen()
                next(g)
                # Now that __del__ is finished, subtype_dealloc will proceed
                # to call list_dealloc, which also uses the trashcan mechanism.
     
        def make_nested():
            """Create a sufficiently nested container object so that the
            trashcan mechanism is invoked when deallocating it."""
            x = C([])
            for i in range(NESTING):
                x = [C([x])]
            del x
     
        def run_thread():
            """Exercise make_nested() in a loop."""
            while not exit:
                make_nested()
     
        old_checkinterval = sys.getcheckinterval()
        sys.setcheckinterval(3)
        try:
            exit = False
            threads = []
            for i in range(N_THREADS):
                t = threading.Thread(target=run_thread)
                threads.append(t)
            for t in threads:
                t.start()
            time.sleep(0.01)
            exit = True
            for t in threads:
                t.join()
        finally:
            pass
            sys.setcheckinterval(old_checkinterval)
        self.assertEqual(len(C.inits), len(C.dels)) 

def test_trashcan_threads(self):
        # Issue #13992: trashcan mechanism should be thread-safe
        NESTING = 60
        N_THREADS = 2

        def sleeper_gen():
            """A generator that releases the GIL when closed or dealloc'ed."""
            try:
                yield
            finally:
                time.sleep(0.000001)

        class C(list):
            # Appending to a list is atomic, which avoids the use of a lock.
            inits = []
            dels = []
            def __init__(self, alist):
                self[:] = alist
                C.inits.append(None)
            def __del__(self):
                # This __del__ is called by subtype_dealloc().
                C.dels.append(None)
                # `g` will release the GIL when garbage-collected.  This
                # helps assert subtype_dealloc's behaviour when threads
                # switch in the middle of it.
                g = sleeper_gen()
                next(g)
                # Now that __del__ is finished, subtype_dealloc will proceed
                # to call list_dealloc, which also uses the trashcan mechanism.

        def make_nested():
            """Create a sufficiently nested container object so that the
            trashcan mechanism is invoked when deallocating it."""
            x = C([])
            for i in range(NESTING):
                x = [C([x])]
            del x

        def run_thread():
            """Exercise make_nested() in a loop."""
            while not exit:
                make_nested()

        old_checkinterval = sys.getcheckinterval()
        sys.setcheckinterval(3)
        try:
            exit = []
            threads = []
            for i in range(N_THREADS):
                t = threading.Thread(target=run_thread)
                threads.append(t)
            with start_threads(threads, lambda: exit.append(1)):
                time.sleep(1.0)
        finally:
            sys.setcheckinterval(old_checkinterval)
        gc.collect()
        self.assertEqual(len(C.inits), len(C.dels))