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246 lines
10 KiB
246 lines
10 KiB
3 years ago
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"""PyUnit testing that threads honor our signal semantics"""
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import unittest
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import signal
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import os
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import sys
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from test.support import threading_helper
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import _thread as thread
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import time
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if (sys.platform[:3] == 'win'):
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raise unittest.SkipTest("Can't test signal on %s" % sys.platform)
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process_pid = os.getpid()
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signalled_all=thread.allocate_lock()
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USING_PTHREAD_COND = (sys.thread_info.name == 'pthread'
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and sys.thread_info.lock == 'mutex+cond')
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def registerSignals(for_usr1, for_usr2, for_alrm):
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usr1 = signal.signal(signal.SIGUSR1, for_usr1)
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usr2 = signal.signal(signal.SIGUSR2, for_usr2)
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alrm = signal.signal(signal.SIGALRM, for_alrm)
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return usr1, usr2, alrm
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# The signal handler. Just note that the signal occurred and
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# from who.
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def handle_signals(sig,frame):
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signal_blackboard[sig]['tripped'] += 1
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signal_blackboard[sig]['tripped_by'] = thread.get_ident()
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# a function that will be spawned as a separate thread.
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def send_signals():
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os.kill(process_pid, signal.SIGUSR1)
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os.kill(process_pid, signal.SIGUSR2)
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signalled_all.release()
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class ThreadSignals(unittest.TestCase):
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def test_signals(self):
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with threading_helper.wait_threads_exit():
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# Test signal handling semantics of threads.
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# We spawn a thread, have the thread send two signals, and
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# wait for it to finish. Check that we got both signals
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# and that they were run by the main thread.
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signalled_all.acquire()
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self.spawnSignallingThread()
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signalled_all.acquire()
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# the signals that we asked the kernel to send
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# will come back, but we don't know when.
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# (it might even be after the thread exits
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# and might be out of order.) If we haven't seen
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# the signals yet, send yet another signal and
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# wait for it return.
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if signal_blackboard[signal.SIGUSR1]['tripped'] == 0 \
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or signal_blackboard[signal.SIGUSR2]['tripped'] == 0:
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try:
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signal.alarm(1)
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signal.pause()
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finally:
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signal.alarm(0)
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self.assertEqual( signal_blackboard[signal.SIGUSR1]['tripped'], 1)
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self.assertEqual( signal_blackboard[signal.SIGUSR1]['tripped_by'],
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thread.get_ident())
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self.assertEqual( signal_blackboard[signal.SIGUSR2]['tripped'], 1)
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self.assertEqual( signal_blackboard[signal.SIGUSR2]['tripped_by'],
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thread.get_ident())
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signalled_all.release()
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def spawnSignallingThread(self):
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thread.start_new_thread(send_signals, ())
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def alarm_interrupt(self, sig, frame):
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raise KeyboardInterrupt
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@unittest.skipIf(USING_PTHREAD_COND,
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'POSIX condition variables cannot be interrupted')
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@unittest.skipIf(sys.platform.startswith('linux') and
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not sys.thread_info.version,
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'Issue 34004: musl does not allow interruption of locks '
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'by signals.')
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# Issue #20564: sem_timedwait() cannot be interrupted on OpenBSD
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@unittest.skipIf(sys.platform.startswith('openbsd'),
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'lock cannot be interrupted on OpenBSD')
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def test_lock_acquire_interruption(self):
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# Mimic receiving a SIGINT (KeyboardInterrupt) with SIGALRM while stuck
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# in a deadlock.
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# XXX this test can fail when the legacy (non-semaphore) implementation
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# of locks is used in thread_pthread.h, see issue #11223.
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oldalrm = signal.signal(signal.SIGALRM, self.alarm_interrupt)
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try:
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lock = thread.allocate_lock()
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lock.acquire()
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signal.alarm(1)
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t1 = time.monotonic()
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self.assertRaises(KeyboardInterrupt, lock.acquire, timeout=5)
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dt = time.monotonic() - t1
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# Checking that KeyboardInterrupt was raised is not sufficient.
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# We want to assert that lock.acquire() was interrupted because
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# of the signal, not that the signal handler was called immediately
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# after timeout return of lock.acquire() (which can fool assertRaises).
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self.assertLess(dt, 3.0)
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finally:
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signal.alarm(0)
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signal.signal(signal.SIGALRM, oldalrm)
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@unittest.skipIf(USING_PTHREAD_COND,
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'POSIX condition variables cannot be interrupted')
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@unittest.skipIf(sys.platform.startswith('linux') and
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not sys.thread_info.version,
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'Issue 34004: musl does not allow interruption of locks '
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'by signals.')
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# Issue #20564: sem_timedwait() cannot be interrupted on OpenBSD
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@unittest.skipIf(sys.platform.startswith('openbsd'),
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'lock cannot be interrupted on OpenBSD')
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def test_rlock_acquire_interruption(self):
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# Mimic receiving a SIGINT (KeyboardInterrupt) with SIGALRM while stuck
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# in a deadlock.
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# XXX this test can fail when the legacy (non-semaphore) implementation
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# of locks is used in thread_pthread.h, see issue #11223.
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oldalrm = signal.signal(signal.SIGALRM, self.alarm_interrupt)
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try:
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rlock = thread.RLock()
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# For reentrant locks, the initial acquisition must be in another
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# thread.
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def other_thread():
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rlock.acquire()
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with threading_helper.wait_threads_exit():
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thread.start_new_thread(other_thread, ())
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# Wait until we can't acquire it without blocking...
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while rlock.acquire(blocking=False):
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rlock.release()
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time.sleep(0.01)
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signal.alarm(1)
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t1 = time.monotonic()
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self.assertRaises(KeyboardInterrupt, rlock.acquire, timeout=5)
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dt = time.monotonic() - t1
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# See rationale above in test_lock_acquire_interruption
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self.assertLess(dt, 3.0)
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finally:
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signal.alarm(0)
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signal.signal(signal.SIGALRM, oldalrm)
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def acquire_retries_on_intr(self, lock):
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self.sig_recvd = False
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def my_handler(signal, frame):
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self.sig_recvd = True
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old_handler = signal.signal(signal.SIGUSR1, my_handler)
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try:
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def other_thread():
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# Acquire the lock in a non-main thread, so this test works for
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# RLocks.
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lock.acquire()
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# Wait until the main thread is blocked in the lock acquire, and
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# then wake it up with this.
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time.sleep(0.5)
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os.kill(process_pid, signal.SIGUSR1)
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# Let the main thread take the interrupt, handle it, and retry
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# the lock acquisition. Then we'll let it run.
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time.sleep(0.5)
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lock.release()
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with threading_helper.wait_threads_exit():
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thread.start_new_thread(other_thread, ())
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# Wait until we can't acquire it without blocking...
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while lock.acquire(blocking=False):
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lock.release()
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time.sleep(0.01)
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result = lock.acquire() # Block while we receive a signal.
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self.assertTrue(self.sig_recvd)
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self.assertTrue(result)
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finally:
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signal.signal(signal.SIGUSR1, old_handler)
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def test_lock_acquire_retries_on_intr(self):
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self.acquire_retries_on_intr(thread.allocate_lock())
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def test_rlock_acquire_retries_on_intr(self):
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self.acquire_retries_on_intr(thread.RLock())
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def test_interrupted_timed_acquire(self):
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# Test to make sure we recompute lock acquisition timeouts when we
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# receive a signal. Check this by repeatedly interrupting a lock
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# acquire in the main thread, and make sure that the lock acquire times
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# out after the right amount of time.
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# NOTE: this test only behaves as expected if C signals get delivered
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# to the main thread. Otherwise lock.acquire() itself doesn't get
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# interrupted and the test trivially succeeds.
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self.start = None
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self.end = None
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self.sigs_recvd = 0
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done = thread.allocate_lock()
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done.acquire()
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lock = thread.allocate_lock()
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lock.acquire()
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def my_handler(signum, frame):
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self.sigs_recvd += 1
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old_handler = signal.signal(signal.SIGUSR1, my_handler)
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try:
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def timed_acquire():
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self.start = time.monotonic()
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lock.acquire(timeout=0.5)
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self.end = time.monotonic()
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def send_signals():
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for _ in range(40):
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time.sleep(0.02)
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os.kill(process_pid, signal.SIGUSR1)
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done.release()
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with threading_helper.wait_threads_exit():
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# Send the signals from the non-main thread, since the main thread
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# is the only one that can process signals.
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thread.start_new_thread(send_signals, ())
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timed_acquire()
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# Wait for thread to finish
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done.acquire()
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# This allows for some timing and scheduling imprecision
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self.assertLess(self.end - self.start, 2.0)
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self.assertGreater(self.end - self.start, 0.3)
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# If the signal is received several times before PyErr_CheckSignals()
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# is called, the handler will get called less than 40 times. Just
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# check it's been called at least once.
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self.assertGreater(self.sigs_recvd, 0)
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finally:
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signal.signal(signal.SIGUSR1, old_handler)
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def setUpModule():
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global signal_blackboard
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signal_blackboard = { signal.SIGUSR1 : {'tripped': 0, 'tripped_by': 0 },
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signal.SIGUSR2 : {'tripped': 0, 'tripped_by': 0 },
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signal.SIGALRM : {'tripped': 0, 'tripped_by': 0 } }
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oldsigs = registerSignals(handle_signals, handle_signals, handle_signals)
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unittest.addModuleCleanup(registerSignals, *oldsigs)
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if __name__ == '__main__':
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unittest.main()
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