# Very rudimentary test of threading module
import test.test_support
from test.test_support import verbose
from test.script_helper import assert_python_ok
import random
import re
import sys
thread = test.test_support.import_module('thread')
threading = test.test_support.import_module('threading')
import time
import unittest
import weakref
import os
import subprocess
from test import lock_tests
# A trivial mutable counter.
class Counter(object):
def __init__(self):
self.value = 0
def inc(self):
self.value += 1
def dec(self):
self.value -= 1
def get(self):
return self.value
class TestThread(threading.Thread):
def __init__(self, name, testcase, sema, mutex, nrunning):
threading.Thread.__init__(self, name=name)
self.testcase = testcase
self.sema = sema
self.mutex = mutex
self.nrunning = nrunning
def run(self):
delay = random.random() / 10000.0
if verbose:
print 'task %s will run for %.1f usec' % (
self.name, delay * 1e6)
with self.sema:
with self.mutex:
self.nrunning.inc()
if verbose:
print self.nrunning.get(), 'tasks are running'
self.testcase.assertTrue(self.nrunning.get() <= 3)
time.sleep(delay)
if verbose:
print 'task', self.name, 'done'
with self.mutex:
self.nrunning.dec()
self.testcase.assertTrue(self.nrunning.get() >= 0)
if verbose:
print '%s is finished. %d tasks are running' % (
self.name, self.nrunning.get())
class BaseTestCase(unittest.TestCase):
def setUp(self):
self._threads = test.test_support.threading_setup()
def tearDown(self):
test.test_support.threading_cleanup(*self._threads)
test.test_support.reap_children()
class ThreadTests(BaseTestCase):
# Create a bunch of threads, let each do some work, wait until all are
# done.
def test_various_ops(self):
# This takes about n/3 seconds to run (about n/3 clumps of tasks,
# times about 1 second per clump).
NUMTASKS = 10
# no more than 3 of the 10 can run at once
sema = threading.BoundedSemaphore(value=3)
mutex = threading.RLock()
numrunning = Counter()
threads = []
for i in range(NUMTASKS):
t = TestThread("<thread %d>"%i, self, sema, mutex, numrunning)
threads.append(t)
self.assertEqual(t.ident, None)
self.assertTrue(re.match('<TestThread\(.*, initial\)>', repr(t)))
t.start()
if verbose:
print 'waiting for all tasks to complete'
for t in threads:
t.join(NUMTASKS)
self.assertTrue(not t.is_alive())
self.assertNotEqual(t.ident, 0)
self.assertFalse(t.ident is None)
self.assertTrue(re.match('<TestThread\(.*, \w+ -?\d+\)>', repr(t)))
if verbose:
print 'all tasks done'
self.assertEqual(numrunning.get(), 0)
def test_ident_of_no_threading_threads(self):
# The ident still must work for the main thread and dummy threads.
self.assertFalse(threading.currentThread().ident is None)
def f():
ident.append(threading.currentThread().ident)
done.set()
done = threading.Event()
ident = []
thread.start_new_thread(f, ())
done.wait()
self.assertFalse(ident[0] is None)
# Kill the "immortal" _DummyThread
del threading._active[ident[0]]
# run with a small(ish) thread stack size (256kB)
def test_various_ops_small_stack(self):
if verbose:
print 'with 256kB thread stack size...'
try:
threading.stack_size(262144)
except thread.error:
if verbose:
print 'platform does not support changing thread stack size'
return
self.test_various_ops()
threading.stack_size(0)
# run with a large thread stack size (1MB)
def test_various_ops_large_stack(self):
if verbose:
print 'with 1MB thread stack size...'
try:
threading.stack_size(0x100000)
except thread.error:
if verbose:
print 'platform does not support changing thread stack size'
return
self.test_various_ops()
threading.stack_size(0)
def test_foreign_thread(self):
# Check that a "foreign" thread can use the threading module.
def f(mutex):
# Calling current_thread() forces an entry for the foreign
# thread to get made in the threading._active map.
threading.current_thread()
mutex.release()
mutex = threading.Lock()
mutex.acquire()
tid = thread.start_new_thread(f, (mutex,))
# Wait for the thread to finish.
mutex.acquire()
self.assertIn(tid, threading._active)
self.assertIsInstance(threading._active[tid], threading._DummyThread)
del threading._active[tid]
# PyThreadState_SetAsyncExc() is a CPython-only gimmick, not (currently)
# exposed at the Python level. This test relies on ctypes to get at it.
def test_PyThreadState_SetAsyncExc(self):
try:
import ctypes
except ImportError:
if verbose:
print "test_PyThreadState_SetAsyncExc can't import ctypes"
return # can't do anything
set_async_exc = ctypes.pythonapi.PyThreadState_SetAsyncExc
class AsyncExc(Exception):
pass
exception = ctypes.py_object(AsyncExc)
# First check it works when setting the exception from the same thread.
tid = thread.get_ident()
try:
result = set_async_exc(ctypes.c_long(tid), exception)
# The exception is async, so we might have to keep the VM busy until
# it notices.
while True:
pass
except AsyncExc:
pass
else:
# This code is unreachable but it reflects the intent. If we wanted
# to be smarter the above loop wouldn't be infinite.
self.fail("AsyncExc not raised")
try:
self.assertEqual(result, 1) # one thread state modified
except UnboundLocalError:
# The exception was raised too quickly for us to get the result.
pass
# `worker_started` is set by the thread when it's inside a try/except
# block waiting to catch the asynchronously set AsyncExc exception.
# `worker_saw_exception` is set by the thread upon catching that
# exception.
worker_started = threading.Event()
worker_saw_exception = threading.Event()
class Worker(threading.Thread):
def run(self):
self.id = thread.get_ident()
self.finished = False
try:
while True:
worker_started.set()
time.sleep(0.1)
except AsyncExc:
self.finished = True
worker_saw_exception.set()
t = Worker()
t.daemon = True # so if this fails, we don't hang Python at shutdown
t.start()
if verbose:
print " started worker thread"
# Try a thread id that doesn't make sense.
if verbose:
print " trying nonsensical thread id"
result = set_async_exc(ctypes.c_long(-1), exception)
self.assertEqual(result, 0) # no thread states modified
# Now raise an exception in the worker thread.
if verbose:
print " waiting for worker thread to get started"
ret = worker_started.wait()
self.assertTrue(ret)
if verbose:
print " verifying worker hasn't exited"
self.assertTrue(not t.finished)
if verbose:
print " attempting to raise asynch exception in worker"
result = set_async_exc(ctypes.c_long(t.id), exception)
self.assertEqual(result, 1) # one thread state modified
if verbose:
print " waiting for worker to say it caught the exception"
worker_saw_exception.wait(timeout=10)
self.assertTrue(t.finished)
if verbose:
print " all OK -- joining worker"
if t.finished:
t.join()
# else the thread is still running, and we have no way to kill it
def test_limbo_cleanup(self):
# Issue 7481: Failure to start thread should cleanup the limbo map.
def fail_new_thread(*args):
raise thread.error()
_start_new_thread = threading._start_new_thread
threading._start_new_thread = fail_new_thread
try:
t = threading.Thread(target=lambda: None)
self.assertRaises(thread.error, t.start)
self.assertFalse(
t in threading._limbo,
"Failed to cleanup _limbo map on failure of Thread.start().")
finally:
threading._start_new_thread = _start_new_thread
def test_finalize_runnning_thread(self):
# Issue 1402: the PyGILState_Ensure / _Release functions may be called
# very late on python exit: on deallocation of a running thread for
# example.
try:
import ctypes
except ImportError:
if verbose:
print("test_finalize_with_runnning_thread can't import ctypes")
return # can't do anything
rc = subprocess.call([sys.executable, "-c", """if 1:
import ctypes, sys, time, thread
# This lock is used as a simple event variable.
ready = thread.allocate_lock()
ready.acquire()
# Module globals are cleared before __del__ is run
# So we save the functions in class dict
class C:
ensure = ctypes.pythonapi.PyGILState_Ensure
release = ctypes.pythonapi.PyGILState_Release
def __del__(self):
state = self.ensure()
self.release(state)
def waitingThread():
x = C()
ready.release()
time.sleep(100)
thread.start_new_thread(waitingThread, ())
ready.acquire() # Be sure the other thread is waiting.
sys.exit(42)
"""])
self.assertEqual(rc, 42)
def test_finalize_with_trace(self):
# Issue1733757
# Avoid a deadlock when sys.settrace steps into threading._shutdown
p = subprocess.Popen([sys.executable, "-c", """if 1:
import sys, threading
# A deadlock-killer, to prevent the
# testsuite to hang forever
def killer():
import os, time
time.sleep(2)
print 'program blocked; aborting'
os._exit(2)
t = threading.Thread(target=killer)
t.daemon = True
t.start()
# This is the trace function
def func(frame, event, arg):
threading.current_thread()
return func
sys.settrace(func)
"""],
stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
self.addCleanup(p.stdout.close)
self.addCleanup(p.stderr.close)
stdout, stderr = p.communicate()
rc = p.returncode
self.assertFalse(rc == 2, "interpreted was blocked")
self.assertTrue(rc == 0,
"Unexpected error: " + repr(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_no_refcycle_through_target(self):
class RunSelfFunction(object):
def __init__(self, should_raise):
# The links in this refcycle from Thread back to self
# should be cleaned up when the thread completes.
self.should_raise = should_raise
self.thread = threading.Thread(target=self._run,
args=(self,),
kwargs={'yet_another':self})
self.thread.start()
def _run(self, other_ref, yet_another):
if self.should_raise:
raise SystemExit
cyclic_object = RunSelfFunction(should_raise=False)
weak_cyclic_object = weakref.ref(cyclic_object)
cyclic_object.thread.join()
del cyclic_object
self.assertEqual(None, weak_cyclic_object(),
msg=('%d references still around' %
sys.getrefcount(weak_cyclic_object())))
raising_cyclic_object = RunSelfFunction(should_raise=True)
weak_raising_cyclic_object = weakref.ref(raising_cyclic_object)
raising_cyclic_object.thread.join()
del raising_cyclic_object
self.assertEqual(None, weak_raising_cyclic_object(),
msg=('%d references still around' %
sys.getrefcount(weak_raising_cyclic_object())))
@unittest.skipUnless(hasattr(os, 'fork'), 'test needs fork()')
def test_dummy_thread_after_fork(self):
# Issue #14308: a dummy thread in the active list doesn't mess up
# the after-fork mechanism.
code = """if 1:
import thread, threading, os, time
def background_thread(evt):
# Creates and registers the _DummyThread instance
threading.current_thread()
evt.set()
time.sleep(10)
evt = threading.Event()
thread.start_new_thread(background_thread, (evt,))
evt.wait()
assert threading.active_count() == 2, threading.active_count()
if os.fork() == 0:
assert threading.active_count() == 1, threading.active_count()
os._exit(0)
else:
os.wait()
"""
_, out, err = assert_python_ok("-c", code)
self.assertEqual(out, '')
self.assertEqual(err, '')
class ThreadJoinOnShutdown(BaseTestCase):
# Between fork() and exec(), only async-safe functions are allowed (issues
# #12316 and #11870), and fork() from a worker thread is known to trigger
# problems with some operating systems (issue #3863): skip problematic tests
# on platforms known to behave badly.
platforms_to_skip = ('freebsd4', 'freebsd5', 'freebsd6', 'netbsd5',
'os2emx')
def _run_and_join(self, script):
script = """if 1:
import sys, os, time, threading
# a thread, which waits for the main program to terminate
def joiningfunc(mainthread):
mainthread.join()
print 'end of thread'
\n""" + script
p = subprocess.Popen([sys.executable, "-c", script], stdout=subprocess.PIPE)
rc = p.wait()
data = p.stdout.read().replace('\r', '')
p.stdout.close()
self.assertEqual(data, "end of main\nend of thread\n")
self.assertFalse(rc == 2, "interpreter was blocked")
self.assertTrue(rc == 0, "Unexpected error")
def test_1_join_on_shutdown(self):
# The usual case: on exit, wait for a non-daemon thread
script = """if 1:
import os
t = threading.Thread(target=joiningfunc,
args=(threading.current_thread(),))
t.start()
time.sleep(0.1)
print 'end of main'
"""
self._run_and_join(script)
@unittest.skipUnless(hasattr(os, 'fork'), "needs os.fork()")
@unittest.skipIf(sys.platform in platforms_to_skip, "due to known OS bug")
def test_2_join_in_forked_process(self):
# Like the test above, but from a forked interpreter
script = """if 1:
childpid = os.fork()
if childpid != 0:
os.waitpid(childpid, 0)
sys.exit(0)
t = threading.Thread(target=joiningfunc,
args=(threading.current_thread(),))
t.start()
print 'end of main'
"""
self._run_and_join(script)
@unittest.skipUnless(hasattr(os, 'fork'), "needs os.fork()")
@unittest.skipIf(sys.platform in platforms_to_skip, "due to known OS bug")
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 assertScriptHasOutput(self, script, expected_output):
p = subprocess.Popen([sys.executable, "-c", script],
stdout=subprocess.PIPE)
rc = p.wait()
data = p.stdout.read().decode().replace('\r', '')
self.assertEqual(rc, 0, "Unexpected error")
self.assertEqual(data, expected_output)
@unittest.skipUnless(hasattr(os, 'fork'), "needs os.fork()")
@unittest.skipIf(sys.platform in platforms_to_skip, "due to known OS bug")
def test_4_joining_across_fork_in_worker_thread(self):
# There used to be a possible deadlock when forking from a child
# thread. See http://bugs.python.org/issue6643.
# The script takes the following steps:
# - The main thread in the parent process starts a new thread and then
# tries to join it.
# - The join operation acquires the Lock inside the thread's _block
# Condition. (See threading.py:Thread.join().)
# - We stub out the acquire method on the condition to force it to wait
# until the child thread forks. (See LOCK ACQUIRED HERE)
# - The child thread forks. (See LOCK HELD and WORKER THREAD FORKS
# HERE)
# - The main thread of the parent process enters Condition.wait(),
# which releases the lock on the child thread.
# - The child process returns. Without the necessary fix, when the
# main thread of the child process (which used to be the child thread
# in the parent process) attempts to exit, it will try to acquire the
# lock in the Thread._block Condition object and hang, because the
# lock was held across the fork.
script = """if 1:
import os, time, threading
finish_join = False
start_fork = False
def worker():
# Wait until this thread's lock is acquired before forking to
# create the deadlock.
global finish_join
while not start_fork:
time.sleep(0.01)
# LOCK HELD: Main thread holds lock across this call.
childpid = os.fork()
finish_join = True
if childpid != 0:
# Parent process just waits for child.
os.waitpid(childpid, 0)
# Child process should just return.
w = threading.Thread(target=worker)
# Stub out the private condition variable's lock acquire method.
# This acquires the lock and then waits until the child has forked
# before returning, which will release the lock soon after. If
# someone else tries to fix this test case by acquiring this lock
# before forking instead of resetting it, the test case will
# deadlock when it shouldn't.
condition = w._block
orig_acquire = condition.acquire
call_count_lock = threading.Lock()
call_count = 0
def my_acquire():
global call_count
global start_fork
orig_acquire() # LOCK ACQUIRED HERE
start_fork = True
if call_count == 0:
while not finish_join:
time.sleep(0.01) # WORKER THREAD FORKS HERE
with call_count_lock:
call_count += 1
condition.acquire = my_acquire
w.start()
w.join()
print('end of main')
"""
self.assertScriptHasOutput(script, "end of main\n")
@unittest.skipUnless(hasattr(os, 'fork'), "needs os.fork()")
@unittest.skipIf(sys.platform in platforms_to_skip, "due to known OS bug")
def test_5_clear_waiter_locks_to_avoid_crash(self):
# Check that a spawned thread that forks doesn't segfault on certain
# platforms, namely OS X. This used to happen if there was a waiter
# lock in the thread's condition variable's waiters list. Even though
# we know the lock will be held across the fork, it is not safe to
# release locks held across forks on all platforms, so releasing the
# waiter lock caused a segfault on OS X. Furthermore, since locks on
# OS X are (as of this writing) implemented with a mutex + condition
# variable instead of a semaphore, while we know that the Python-level
# lock will be acquired, we can't know if the internal mutex will be
# acquired at the time of the fork.
script = """if True:
import os, time, threading
start_fork = False
def worker():
# Wait until the main thread has attempted to join this thread
# before continuing.
while not start_fork:
time.sleep(0.01)
childpid = os.fork()
if childpid != 0:
# Parent process just waits for child.
(cpid, rc) = os.waitpid(childpid, 0)
assert cpid == childpid
assert rc == 0
print('end of worker thread')
else:
# Child process should just return.
pass
w = threading.Thread(target=worker)
# Stub out the private condition variable's _release_save method.
# This releases the condition's lock and flips the global that
# causes the worker to fork. At this point, the problematic waiter
# lock has been acquired once by the waiter and has been put onto
# the waiters list.
condition = w._block
orig_release_save = condition._release_save
def my_release_save():
global start_fork
orig_release_save()
# Waiter lock held here, condition lock released.
start_fork = True
condition._release_save = my_release_save
w.start()
w.join()
print('end of main thread')
"""
output = "end of worker thread\nend of main thread\n"
self.assertScriptHasOutput(script, output)
@unittest.skipUnless(hasattr(os, 'fork'), "needs os.fork()")
@unittest.skipIf(sys.platform in platforms_to_skip, "due to known OS bug")
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()
class ThreadingExceptionTests(BaseTestCase):
# A RuntimeError should be raised if Thread.start() is called
# multiple times.
def test_start_thread_again(self):
thread = threading.Thread()
thread.start()
self.assertRaises(RuntimeError, thread.start)
def test_joining_current_thread(self):
current_thread = threading.current_thread()
self.assertRaises(RuntimeError, current_thread.join);
def test_joining_inactive_thread(self):
thread = threading.Thread()
self.assertRaises(RuntimeError, thread.join)
def test_daemonize_active_thread(self):
thread = threading.Thread()
thread.start()
self.assertRaises(RuntimeError, setattr, thread, "daemon", True)
class LockTests(lock_tests.LockTests):
locktype = staticmethod(threading.Lock)
class RLockTests(lock_tests.RLockTests):
locktype = staticmethod(threading.RLock)
class EventTests(lock_tests.EventTests):
eventtype = staticmethod(threading.Event)
class ConditionAsRLockTests(lock_tests.RLockTests):
# An Condition uses an RLock by default and exports its API.
locktype = staticmethod(threading.Condition)
class ConditionTests(lock_tests.ConditionTests):
condtype = staticmethod(threading.Condition)
class SemaphoreTests(lock_tests.SemaphoreTests):
semtype = staticmethod(threading.Semaphore)
class BoundedSemaphoreTests(lock_tests.BoundedSemaphoreTests):
semtype = staticmethod(threading.BoundedSemaphore)
@unittest.skipUnless(sys.platform == 'darwin', 'test macosx problem')
def test_recursion_limit(self):
# Issue 9670
# test that excessive recursion within a non-main thread causes
# an exception rather than crashing the interpreter on platforms
# like Mac OS X or FreeBSD which have small default stack sizes
# for threads
script = """if True:
import threading
def recurse():
return recurse()
def outer():
try:
recurse()
except RuntimeError:
pass
w = threading.Thread(target=outer)
w.start()
w.join()
print('end of main thread')
"""
expected_output = "end of main thread\n"
p = subprocess.Popen([sys.executable, "-c", script],
stdout=subprocess.PIPE)
stdout, stderr = p.communicate()
data = stdout.decode().replace('\r', '')
self.assertEqual(p.returncode, 0, "Unexpected error")
self.assertEqual(data, expected_output)
def test_main():
test.test_support.run_unittest(LockTests, RLockTests, EventTests,
ConditionAsRLockTests, ConditionTests,
SemaphoreTests, BoundedSemaphoreTests,
ThreadTests,
ThreadJoinOnShutdown,
ThreadingExceptionTests,
)
if __name__ == "__main__":
test_main()