1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
"""PyUnit testing that threads honor our signal semantics"""
import unittest
import signal
import os
import sys
from test.support import run_unittest, import_module
thread = import_module('_thread')
import time
if sys.platform[:3] in ('win', 'os2') or sys.platform=='riscos':
raise unittest.SkipTest("Can't test signal on %s" % sys.platform)
process_pid = os.getpid()
signalled_all=thread.allocate_lock()
info = thread.info()
USING_PTHREAD_COND = (info['name'] == 'pthread'
and info['lock_implementation'] == 'mutex+cond')
def registerSignals(for_usr1, for_usr2, for_alrm):
usr1 = signal.signal(signal.SIGUSR1, for_usr1)
usr2 = signal.signal(signal.SIGUSR2, for_usr2)
alrm = signal.signal(signal.SIGALRM, for_alrm)
return usr1, usr2, alrm
# The signal handler. Just note that the signal occurred and
# from who.
def handle_signals(sig,frame):
signal_blackboard[sig]['tripped'] += 1
signal_blackboard[sig]['tripped_by'] = thread.get_ident()
# a function that will be spawned as a separate thread.
def send_signals():
os.kill(process_pid, signal.SIGUSR1)
os.kill(process_pid, signal.SIGUSR2)
signalled_all.release()
class ThreadSignals(unittest.TestCase):
def test_signals(self):
# Test signal handling semantics of threads.
# We spawn a thread, have the thread send two signals, and
# wait for it to finish. Check that we got both signals
# and that they were run by the main thread.
signalled_all.acquire()
self.spawnSignallingThread()
signalled_all.acquire()
# the signals that we asked the kernel to send
# will come back, but we don't know when.
# (it might even be after the thread exits
# and might be out of order.) If we haven't seen
# the signals yet, send yet another signal and
# wait for it return.
if signal_blackboard[signal.SIGUSR1]['tripped'] == 0 \
or signal_blackboard[signal.SIGUSR2]['tripped'] == 0:
signal.alarm(1)
signal.pause()
signal.alarm(0)
self.assertEqual( signal_blackboard[signal.SIGUSR1]['tripped'], 1)
self.assertEqual( signal_blackboard[signal.SIGUSR1]['tripped_by'],
thread.get_ident())
self.assertEqual( signal_blackboard[signal.SIGUSR2]['tripped'], 1)
self.assertEqual( signal_blackboard[signal.SIGUSR2]['tripped_by'],
thread.get_ident())
signalled_all.release()
def spawnSignallingThread(self):
thread.start_new_thread(send_signals, ())
def alarm_interrupt(self, sig, frame):
raise KeyboardInterrupt
@unittest.skipIf(USING_PTHREAD_COND,
'POSIX condition variables cannot be interrupted')
def test_lock_acquire_interruption(self):
# Mimic receiving a SIGINT (KeyboardInterrupt) with SIGALRM while stuck
# in a deadlock.
# XXX this test can fail when the legacy (non-semaphore) implementation
# of locks is used in thread_pthread.h, see issue #11223.
oldalrm = signal.signal(signal.SIGALRM, self.alarm_interrupt)
try:
lock = thread.allocate_lock()
lock.acquire()
signal.alarm(1)
t1 = time.time()
self.assertRaises(KeyboardInterrupt, lock.acquire, timeout=5)
dt = time.time() - t1
# Checking that KeyboardInterrupt was raised is not sufficient.
# We want to assert that lock.acquire() was interrupted because
# of the signal, not that the signal handler was called immediately
# after timeout return of lock.acquire() (which can fool assertRaises).
self.assertLess(dt, 3.0)
finally:
signal.signal(signal.SIGALRM, oldalrm)
@unittest.skipIf(USING_PTHREAD_COND,
'POSIX condition variables cannot be interrupted')
def test_rlock_acquire_interruption(self):
# Mimic receiving a SIGINT (KeyboardInterrupt) with SIGALRM while stuck
# in a deadlock.
# XXX this test can fail when the legacy (non-semaphore) implementation
# of locks is used in thread_pthread.h, see issue #11223.
oldalrm = signal.signal(signal.SIGALRM, self.alarm_interrupt)
try:
rlock = thread.RLock()
# For reentrant locks, the initial acquisition must be in another
# thread.
def other_thread():
rlock.acquire()
thread.start_new_thread(other_thread, ())
# Wait until we can't acquire it without blocking...
while rlock.acquire(blocking=False):
rlock.release()
time.sleep(0.01)
signal.alarm(1)
t1 = time.time()
self.assertRaises(KeyboardInterrupt, rlock.acquire, timeout=5)
dt = time.time() - t1
# See rationale above in test_lock_acquire_interruption
self.assertLess(dt, 3.0)
finally:
signal.signal(signal.SIGALRM, oldalrm)
def acquire_retries_on_intr(self, lock):
self.sig_recvd = False
def my_handler(signal, frame):
self.sig_recvd = True
old_handler = signal.signal(signal.SIGUSR1, my_handler)
try:
def other_thread():
# Acquire the lock in a non-main thread, so this test works for
# RLocks.
lock.acquire()
# Wait until the main thread is blocked in the lock acquire, and
# then wake it up with this.
time.sleep(0.5)
os.kill(process_pid, signal.SIGUSR1)
# Let the main thread take the interrupt, handle it, and retry
# the lock acquisition. Then we'll let it run.
time.sleep(0.5)
lock.release()
thread.start_new_thread(other_thread, ())
# Wait until we can't acquire it without blocking...
while lock.acquire(blocking=False):
lock.release()
time.sleep(0.01)
result = lock.acquire() # Block while we receive a signal.
self.assertTrue(self.sig_recvd)
self.assertTrue(result)
finally:
signal.signal(signal.SIGUSR1, old_handler)
def test_lock_acquire_retries_on_intr(self):
self.acquire_retries_on_intr(thread.allocate_lock())
def test_rlock_acquire_retries_on_intr(self):
self.acquire_retries_on_intr(thread.RLock())
def test_interrupted_timed_acquire(self):
# Test to make sure we recompute lock acquisition timeouts when we
# receive a signal. Check this by repeatedly interrupting a lock
# acquire in the main thread, and make sure that the lock acquire times
# out after the right amount of time.
# NOTE: this test only behaves as expected if C signals get delivered
# to the main thread. Otherwise lock.acquire() itself doesn't get
# interrupted and the test trivially succeeds.
self.start = None
self.end = None
self.sigs_recvd = 0
done = thread.allocate_lock()
done.acquire()
lock = thread.allocate_lock()
lock.acquire()
def my_handler(signum, frame):
self.sigs_recvd += 1
old_handler = signal.signal(signal.SIGUSR1, my_handler)
try:
def timed_acquire():
self.start = time.time()
lock.acquire(timeout=0.5)
self.end = time.time()
def send_signals():
for _ in range(40):
time.sleep(0.02)
os.kill(process_pid, signal.SIGUSR1)
done.release()
# Send the signals from the non-main thread, since the main thread
# is the only one that can process signals.
thread.start_new_thread(send_signals, ())
timed_acquire()
# Wait for thread to finish
done.acquire()
# This allows for some timing and scheduling imprecision
self.assertLess(self.end - self.start, 2.0)
self.assertGreater(self.end - self.start, 0.3)
# If the signal is received several times before PyErr_CheckSignals()
# is called, the handler will get called less than 40 times. Just
# check it's been called at least once.
self.assertGreater(self.sigs_recvd, 0)
finally:
signal.signal(signal.SIGUSR1, old_handler)
def test_main():
global signal_blackboard
signal_blackboard = { signal.SIGUSR1 : {'tripped': 0, 'tripped_by': 0 },
signal.SIGUSR2 : {'tripped': 0, 'tripped_by': 0 },
signal.SIGALRM : {'tripped': 0, 'tripped_by': 0 } }
oldsigs = registerSignals(handle_signals, handle_signals, handle_signals)
try:
run_unittest(ThreadSignals)
finally:
registerSignals(*oldsigs)
if __name__ == '__main__':
test_main()
|
