"""
Various tests for synchronization primitives.
"""
import sys
import time
from thread import start_new_thread, get_ident
import threading
import unittest
from test import test_support as support
def _wait():
# A crude wait/yield function not relying on synchronization primitives.
time.sleep(0.01)
class Bunch(object):
"""
A bunch of threads.
"""
def __init__(self, f, n, wait_before_exit=False):
"""
Construct a bunch of `n` threads running the same function `f`.
If `wait_before_exit` is True, the threads won't terminate until
do_finish() is called.
"""
self.f = f
self.n = n
self.started = []
self.finished = []
self._can_exit = not wait_before_exit
def task():
tid = get_ident()
self.started.append(tid)
try:
f()
finally:
self.finished.append(tid)
while not self._can_exit:
_wait()
for i in range(n):
start_new_thread(task, ())
def wait_for_started(self):
while len(self.started) < self.n:
_wait()
def wait_for_finished(self):
while len(self.finished) < self.n:
_wait()
def do_finish(self):
self._can_exit = True
class BaseTestCase(unittest.TestCase):
def setUp(self):
self._threads = support.threading_setup()
def tearDown(self):
support.threading_cleanup(*self._threads)
support.reap_children()
class BaseLockTests(BaseTestCase):
"""
Tests for both recursive and non-recursive locks.
"""
def test_constructor(self):
lock = self.locktype()
del lock
def test_acquire_destroy(self):
lock = self.locktype()
lock.acquire()
del lock
def test_acquire_release(self):
lock = self.locktype()
lock.acquire()
lock.release()
del lock
def test_try_acquire(self):
lock = self.locktype()
self.assertTrue(lock.acquire(False))
lock.release()
def test_try_acquire_contended(self):
lock = self.locktype()
lock.acquire()
result = []
def f():
result.append(lock.acquire(False))
Bunch(f, 1).wait_for_finished()
self.assertFalse(result[0])
lock.release()
def test_acquire_contended(self):
lock = self.locktype()
lock.acquire()
N = 5
def f():
lock.acquire()
lock.release()
b = Bunch(f, N)
b.wait_for_started()
_wait()
self.assertEqual(len(b.finished), 0)
lock.release()
b.wait_for_finished()
self.assertEqual(len(b.finished), N)
def test_with(self):
lock = self.locktype()
def f():
lock.acquire()
lock.release()
def _with(err=None):
with lock:
if err is not None:
raise err
_with()
# Check the lock is unacquired
Bunch(f, 1).wait_for_finished()
self.assertRaises(TypeError, _with, TypeError)
# Check the lock is unacquired
Bunch(f, 1).wait_for_finished()
def test_thread_leak(self):
# The lock shouldn't leak a Thread instance when used from a foreign
# (non-threading) thread.
lock = self.locktype()
def f():
lock.acquire()
lock.release()
n = len(threading.enumerate())
# We run many threads in the hope that existing threads ids won't
# be recycled.
Bunch(f, 15).wait_for_finished()
self.assertEqual(n, len(threading.enumerate()))
class LockTests(BaseLockTests):
"""
Tests for non-recursive, weak locks
(which can be acquired and released from different threads).
"""
def test_reacquire(self):
# Lock needs to be released before re-acquiring.
lock = self.locktype()
phase = []
def f():
lock.acquire()
phase.append(None)
lock.acquire()
phase.append(None)
start_new_thread(f, ())
while len(phase) == 0:
_wait()
_wait()
self.assertEqual(len(phase), 1)
lock.release()
while len(phase) == 1:
_wait()
self.assertEqual(len(phase), 2)
def test_different_thread(self):
# Lock can be released from a different thread.
lock = self.locktype()
lock.acquire()
def f():
lock.release()
b = Bunch(f, 1)
b.wait_for_finished()
lock.acquire()
lock.release()
class RLockTests(BaseLockTests):
"""
Tests for recursive locks.
"""
def test_reacquire(self):
lock = self.locktype()
lock.acquire()
lock.acquire()
lock.release()
lock.acquire()
lock.release()
lock.release()
def test_release_unacquired(self):
# Cannot release an unacquired lock
lock = self.locktype()
self.assertRaises(RuntimeError, lock.release)
lock.acquire()
lock.acquire()
lock.release()
lock.acquire()
lock.release()
lock.release()
self.assertRaises(RuntimeError, lock.release)
def test_different_thread(self):
# Cannot release from a different thread
lock = self.locktype()
def f():
lock.acquire()
b = Bunch(f, 1, True)
try:
self.assertRaises(RuntimeError, lock.release)
finally:
b.do_finish()
def test__is_owned(self):
lock = self.locktype()
self.assertFalse(lock._is_owned())
lock.acquire()
self.assertTrue(lock._is_owned())
lock.acquire()
self.assertTrue(lock._is_owned())
result = []
def f():
result.append(lock._is_owned())
Bunch(f, 1).wait_for_finished()
self.assertFalse(result[0])
lock.release()
self.assertTrue(lock._is_owned())
lock.release()
self.assertFalse(lock._is_owned())
class EventTests(BaseTestCase):
"""
Tests for Event objects.
"""
def test_is_set(self):
evt = self.eventtype()
self.assertFalse(evt.is_set())
evt.set()
self.assertTrue(evt.is_set())
evt.set()
self.assertTrue(evt.is_set())
evt.clear()
self.assertFalse(evt.is_set())
evt.clear()
self.assertFalse(evt.is_set())
def _check_notify(self, evt):
# All threads get notified
N = 5
results1 = []
results2 = []
def f():
results1.append(evt.wait())
results2.append(evt.wait())
b = Bunch(f, N)
b.wait_for_started()
_wait()
self.assertEqual(len(results1), 0)
evt.set()
b.wait_for_finished()
self.assertEqual(results1, [True] * N)
self.assertEqual(results2, [True] * N)
def test_notify(self):
evt = self.eventtype()
self._check_notify(evt)
# Another time, after an explicit clear()
evt.set()
evt.clear()
self._check_notify(evt)
def test_timeout(self):
evt = self.eventtype()
results1 = []
results2 = []
N = 5
def f():
results1.append(evt.wait(0.0))
t1 = time.time()
r = evt.wait(0.2)
t2 = time.time()
results2.append((r, t2 - t1))
Bunch(f, N).wait_for_finished()
self.assertEqual(results1, [False] * N)
for r, dt in results2:
self.assertFalse(r)
self.assertTrue(dt >= 0.2, dt)
# The event is set
results1 = []
results2 = []
evt.set()
Bunch(f, N).wait_for_finished()
self.assertEqual(results1, [True] * N)
for r, dt in results2:
self.assertTrue(r)
class ConditionTests(BaseTestCase):
"""
Tests for condition variables.
"""
def test_acquire(self):
cond = self.condtype()
# Be default we have an RLock: the condition can be acquired multiple
# times.
cond.acquire()
cond.acquire()
cond.release()
cond.release()
lock = threading.Lock()
cond = self.condtype(lock)
cond.acquire()
self.assertFalse(lock.acquire(False))
cond.release()
self.assertTrue(lock.acquire(False))
self.assertFalse(cond.acquire(False))
lock.release()
with cond:
self.assertFalse(lock.acquire(False))
def test_unacquired_wait(self):
cond = self.condtype()
self.assertRaises(RuntimeError, cond.wait)
def test_unacquired_notify(self):
cond = self.condtype()
self.assertRaises(RuntimeError, cond.notify)
def _check_notify(self, cond):
N = 5
results1 = []
results2 = []
phase_num = 0
def f():
cond.acquire()
cond.wait()
cond.release()
results1.append(phase_num)
cond.acquire()
cond.wait()
cond.release()
results2.append(phase_num)
b = Bunch(f, N)
b.wait_for_started()
_wait()
self.assertEqual(results1, [])
# Notify 3 threads at first
cond.acquire()
cond.notify(3)
_wait()
phase_num = 1
cond.release()
while len(results1) < 3:
_wait()
self.assertEqual(results1, [1] * 3)
self.assertEqual(results2, [])
# Notify 5 threads: they might be in their first or second wait
cond.acquire()
cond.notify(5)
_wait()
phase_num = 2
cond.release()
while len(results1) + len(results2) < 8:
_wait()
self.assertEqual(results1, [1] * 3 + [2] * 2)
self.assertEqual(results2, [2] * 3)
# Notify all threads: they are all in their second wait
cond.acquire()
cond.notify_all()
_wait()
phase_num = 3
cond.release()
while len(results2) < 5:
_wait()
self.assertEqual(results1, [1] * 3 + [2] * 2)
self.assertEqual(results2, [2] * 3 + [3] * 2)
b.wait_for_finished()
def test_notify(self):
cond = self.condtype()
self._check_notify(cond)
# A second time, to check internal state is still ok.
self._check_notify(cond)
def test_timeout(self):
cond = self.condtype()
results = []
N = 5
def f():
cond.acquire()
t1 = time.time()
cond.wait(0.2)
t2 = time.time()
cond.release()
results.append(t2 - t1)
Bunch(f, N).wait_for_finished()
self.assertEqual(len(results), 5)
for dt in results:
self.assertTrue(dt >= 0.2, dt)
class BaseSemaphoreTests(BaseTestCase):
"""
Common tests for {bounded, unbounded} semaphore objects.
"""
def test_constructor(self):
self.assertRaises(ValueError, self.semtype, value = -1)
self.assertRaises(ValueError, self.semtype, value = -sys.maxint)
def test_acquire(self):
sem = self.semtype(1)
sem.acquire()
sem.release()
sem = self.semtype(2)
sem.acquire()
sem.acquire()
sem.release()
sem.release()
def test_acquire_destroy(self):
sem = self.semtype()
sem.acquire()
del sem
def test_acquire_contended(self):
sem = self.semtype(7)
sem.acquire()
N = 10
results1 = []
results2 = []
phase_num = 0
def f():
sem.acquire()
results1.append(phase_num)
sem.acquire()
results2.append(phase_num)
b = Bunch(f, 10)
b.wait_for_started()
while len(results1) + len(results2) < 6:
_wait()
self.assertEqual(results1 + results2, [0] * 6)
phase_num = 1
for i in range(7):
sem.release()
while len(results1) + len(results2) < 13:
_wait()
self.assertEqual(sorted(results1 + results2), [0] * 6 + [1] * 7)
phase_num = 2
for i in range(6):
sem.release()
while len(results1) + len(results2) < 19:
_wait()
self.assertEqual(sorted(results1 + results2), [0] * 6 + [1] * 7 + [2] * 6)
# The semaphore is still locked
self.assertFalse(sem.acquire(False))
# Final release, to let the last thread finish
sem.release()
b.wait_for_finished()
def test_try_acquire(self):
sem = self.semtype(2)
self.assertTrue(sem.acquire(False))
self.assertTrue(sem.acquire(False))
self.assertFalse(sem.acquire(False))
sem.release()
self.assertTrue(sem.acquire(False))
def test_try_acquire_contended(self):
sem = self.semtype(4)
sem.acquire()
results = []
def f():
results.append(sem.acquire(False))
results.append(sem.acquire(False))
Bunch(f, 5).wait_for_finished()
# There can be a thread switch between acquiring the semaphore and
# appending the result, therefore results will not necessarily be
# ordered.
self.assertEqual(sorted(results), [False] * 7 + [True] * 3 )
def test_default_value(self):
# The default initial value is 1.
sem = self.semtype()
sem.acquire()
def f():
sem.acquire()
sem.release()
b = Bunch(f, 1)
b.wait_for_started()
_wait()
self.assertFalse(b.finished)
sem.release()
b.wait_for_finished()
def test_with(self):
sem = self.semtype(2)
def _with(err=None):
with sem:
self.assertTrue(sem.acquire(False))
sem.release()
with sem:
self.assertFalse(sem.acquire(False))
if err:
raise err
_with()
self.assertTrue(sem.acquire(False))
sem.release()
self.assertRaises(TypeError, _with, TypeError)
self.assertTrue(sem.acquire(False))
sem.release()
class SemaphoreTests(BaseSemaphoreTests):
"""
Tests for unbounded semaphores.
"""
def test_release_unacquired(self):
# Unbounded releases are allowed and increment the semaphore's value
sem = self.semtype(1)
sem.release()
sem.acquire()
sem.acquire()
sem.release()
class BoundedSemaphoreTests(BaseSemaphoreTests):
"""
Tests for bounded semaphores.
"""
def test_release_unacquired(self):
# Cannot go past the initial value
sem = self.semtype()
self.assertRaises(ValueError, sem.release)
sem.acquire()
sem.release()
self.assertRaises(ValueError, sem.release)