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2501 lines (2126 loc) · 87.1 KB
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"""
Tests for the threading module.
"""
import test.support
from test.support import threading_helper, requires_subprocess, requires_gil_enabled
from test.support import verbose, cpython_only, os_helper
from test.support.import_helper import ensure_lazy_imports, import_module
from test.support.script_helper import assert_python_ok, assert_python_failure
from test.support import force_not_colorized
import random
import sys
import _thread
import threading
import time
import unittest
import weakref
import os
import subprocess
import signal
import textwrap
import traceback
import warnings
from unittest import mock
from test import lock_tests
from test import support
try:
from concurrent import interpreters
except ImportError:
interpreters = None
threading_helper.requires_working_threading(module=True)
# 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 = ('netbsd5', 'hp-ux11')
def skip_unless_reliable_fork(test):
if not support.has_fork_support:
return unittest.skip("requires working os.fork()")(test)
if sys.platform in platforms_to_skip:
return unittest.skip("due to known OS bug related to thread+fork")(test)
if support.HAVE_ASAN_FORK_BUG:
return unittest.skip("libasan has a pthread_create() dead lock related to thread+fork")(test)
if support.check_sanitizer(thread=True):
return unittest.skip("TSAN doesn't support threads after fork")(test)
return test
def requires_subinterpreters(meth):
"""Decorator to skip a test if subinterpreters are not supported."""
return unittest.skipIf(interpreters is None,
'subinterpreters required')(meth)
def restore_default_excepthook(testcase):
testcase.addCleanup(setattr, threading, 'excepthook', threading.excepthook)
threading.excepthook = threading.__excepthook__
# 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.assertLessEqual(self.nrunning.get(), 3)
time.sleep(delay)
if verbose:
print('task', self.name, 'done')
with self.mutex:
self.nrunning.dec()
self.testcase.assertGreaterEqual(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 = threading_helper.threading_setup()
def tearDown(self):
threading_helper.threading_cleanup(*self._threads)
test.support.reap_children()
class ThreadTests(BaseTestCase):
maxDiff = 9999
@cpython_only
def test_lazy_import(self):
ensure_lazy_imports("threading", {"functools", "warnings"})
@cpython_only
def test_name(self):
def func(): pass
thread = threading.Thread(name="myname1")
self.assertEqual(thread.name, "myname1")
# Convert int name to str
thread = threading.Thread(name=123)
self.assertEqual(thread.name, "123")
# target name is ignored if name is specified
thread = threading.Thread(target=func, name="myname2")
self.assertEqual(thread.name, "myname2")
with mock.patch.object(threading, '_counter', return_value=2):
thread = threading.Thread(name="")
self.assertEqual(thread.name, "Thread-2")
with mock.patch.object(threading, '_counter', return_value=3):
thread = threading.Thread()
self.assertEqual(thread.name, "Thread-3")
with mock.patch.object(threading, '_counter', return_value=5):
thread = threading.Thread(target=func)
self.assertEqual(thread.name, "Thread-5 (func)")
def test_args_argument(self):
# bpo-45735: Using list or tuple as *args* in constructor could
# achieve the same effect.
num_list = [1]
num_tuple = (1,)
str_list = ["str"]
str_tuple = ("str",)
list_in_tuple = ([1],)
tuple_in_list = [(1,)]
test_cases = (
(num_list, lambda arg: self.assertEqual(arg, 1)),
(num_tuple, lambda arg: self.assertEqual(arg, 1)),
(str_list, lambda arg: self.assertEqual(arg, "str")),
(str_tuple, lambda arg: self.assertEqual(arg, "str")),
(list_in_tuple, lambda arg: self.assertEqual(arg, [1])),
(tuple_in_list, lambda arg: self.assertEqual(arg, (1,)))
)
for args, target in test_cases:
with self.subTest(target=target, args=args):
t = threading.Thread(target=target, args=args)
t.start()
t.join()
def test_lock_no_args(self):
threading.Lock() # works
self.assertRaises(TypeError, threading.Lock, 1)
self.assertRaises(TypeError, threading.Lock, a=1)
self.assertRaises(TypeError, threading.Lock, 1, 2, a=1, b=2)
def test_lock_no_subclass(self):
# Intentionally disallow subclasses of threading.Lock because they have
# never been allowed, so why start now just because the type is public?
with self.assertRaises(TypeError):
class MyLock(threading.Lock): pass
def test_lock_or_none(self):
import types
self.assertIsInstance(threading.Lock | None, types.UnionType)
# 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.assertIsNone(t.ident)
self.assertRegex(repr(t), r'^<TestThread\(.*, initial\)>$')
t.start()
if hasattr(threading, 'get_native_id'):
native_ids = set(t.native_id for t in threads) | {threading.get_native_id()}
self.assertNotIn(None, native_ids)
self.assertEqual(len(native_ids), NUMTASKS + 1)
if verbose:
print('waiting for all tasks to complete')
for t in threads:
t.join()
self.assertFalse(t.is_alive())
self.assertNotEqual(t.ident, 0)
self.assertIsNotNone(t.ident)
self.assertRegex(repr(t), r'^<TestThread\(.*, stopped -?\d+\)>$')
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.assertIsNotNone(threading.current_thread().ident)
def f():
ident.append(threading.current_thread().ident)
done.set()
done = threading.Event()
ident = []
with threading_helper.wait_threads_exit():
tid = _thread.start_new_thread(f, ())
done.wait()
self.assertEqual(ident[0], tid)
# run with a small(ish) thread stack size (256 KiB)
def test_various_ops_small_stack(self):
if verbose:
print('with 256 KiB thread stack size...')
try:
threading.stack_size(262144)
except _thread.error:
raise unittest.SkipTest(
'platform does not support changing thread stack size')
self.test_various_ops()
threading.stack_size(0)
# run with a large thread stack size (1 MiB)
def test_various_ops_large_stack(self):
if verbose:
print('with 1 MiB thread stack size...')
try:
threading.stack_size(0x100000)
except _thread.error:
raise unittest.SkipTest(
'platform does not support changing thread stack size')
self.test_various_ops()
threading.stack_size(0)
def test_foreign_thread(self):
# Check that a "foreign" thread can use the threading module.
dummy_thread = None
error = None
def f(mutex):
try:
nonlocal dummy_thread
nonlocal error
# Calling current_thread() forces an entry for the foreign
# thread to get made in the threading._active map.
dummy_thread = threading.current_thread()
tid = dummy_thread.ident
self.assertIn(tid, threading._active)
self.assertIsInstance(dummy_thread, threading._DummyThread)
self.assertIs(threading._active.get(tid), dummy_thread)
# gh-29376
self.assertTrue(
dummy_thread.is_alive(),
'Expected _DummyThread to be considered alive.'
)
self.assertIn('_DummyThread', repr(dummy_thread))
except BaseException as e:
error = e
finally:
mutex.release()
mutex = threading.Lock()
mutex.acquire()
with threading_helper.wait_threads_exit():
tid = _thread.start_new_thread(f, (mutex,))
# Wait for the thread to finish.
mutex.acquire()
if error is not None:
raise error
self.assertEqual(tid, dummy_thread.ident)
# Issue gh-106236:
with self.assertRaises(RuntimeError):
dummy_thread.join()
dummy_thread._started.clear()
with self.assertRaises(RuntimeError):
dummy_thread.is_alive()
# Busy wait for the following condition: after the thread dies, the
# related dummy thread must be removed from threading._active.
timeout = 5
timeout_at = time.monotonic() + timeout
while time.monotonic() < timeout_at:
if threading._active.get(dummy_thread.ident) is not dummy_thread:
break
time.sleep(.1)
else:
self.fail('It was expected that the created threading._DummyThread was removed from threading._active.')
# 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):
ctypes = import_module("ctypes")
set_async_exc = ctypes.pythonapi.PyThreadState_SetAsyncExc
set_async_exc.argtypes = (ctypes.c_ulong, ctypes.py_object)
class AsyncExc(Exception):
pass
exception = ctypes.py_object(AsyncExc)
# First check it works when setting the exception from the same thread.
tid = threading.get_ident()
self.assertIsInstance(tid, int)
self.assertGreater(tid, 0)
try:
result = set_async_exc(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 = threading.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(-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.assertFalse(t.finished)
if verbose:
print(" attempting to raise asynch exception in worker")
result = set_async_exc(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=support.SHORT_TIMEOUT)
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, **kwargs):
raise threading.ThreadError()
_start_joinable_thread = threading._start_joinable_thread
threading._start_joinable_thread = fail_new_thread
try:
t = threading.Thread(target=lambda: None)
self.assertRaises(threading.ThreadError, t.start)
self.assertFalse(
t in threading._limbo,
"Failed to cleanup _limbo map on failure of Thread.start().")
finally:
threading._start_joinable_thread = _start_joinable_thread
def test_finalize_running_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.
if support.check_sanitizer(thread=True):
# the thread running `time.sleep(100)` below will still be alive
# at process exit
self.skipTest("TSAN would report thread leak")
import_module("ctypes")
rc, out, err = assert_python_failure("-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
if support.check_sanitizer(thread=True):
# the thread running `time.sleep(2)` below will still be alive
# at process exit
self.skipTest("TSAN would report thread leak")
assert_python_ok("-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)
""")
def test_join_nondaemon_on_shutdown(self):
# Issue 1722344
# Raising SystemExit skipped threading._shutdown
rc, out, err = assert_python_ok("-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
""")
self.assertEqual(out.strip(),
b"Woke up, sleep function is: <built-in function sleep>")
self.assertEqual(err, b"")
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.getswitchinterval()
try:
for i in range(1, 100):
support.setswitchinterval(i * 0.0002)
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.setswitchinterval(old_interval)
@support.bigmemtest(size=20, memuse=72*2**20, dry_run=False)
def test_join_from_multiple_threads(self, size):
# Thread.join() should be thread-safe
errors = []
def worker():
time.sleep(0.005)
def joiner(thread):
try:
thread.join()
except Exception as e:
errors.append(e)
for N in range(2, 20):
threads = [threading.Thread(target=worker)]
for i in range(N):
threads.append(threading.Thread(target=joiner,
args=(threads[0],)))
for t in threads:
t.start()
time.sleep(0.01)
for t in threads:
t.join()
if errors:
raise errors[0]
def test_join_with_timeout(self):
lock = _thread.allocate_lock()
lock.acquire()
def worker():
lock.acquire()
thread = threading.Thread(target=worker)
thread.start()
thread.join(timeout=0.01)
assert thread.is_alive()
lock.release()
thread.join()
assert not thread.is_alive()
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
restore_default_excepthook(self)
cyclic_object = RunSelfFunction(should_raise=False)
weak_cyclic_object = weakref.ref(cyclic_object)
cyclic_object.thread.join()
del cyclic_object
self.assertIsNone(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.assertIsNone(weak_raising_cyclic_object(),
msg=('%d references still around' %
sys.getrefcount(weak_raising_cyclic_object())))
def test_old_threading_api(self):
# Just a quick sanity check to make sure the old method names are
# still present
t = threading.Thread()
with self.assertWarnsRegex(DeprecationWarning,
r'get the daemon attribute'):
t.isDaemon()
with self.assertWarnsRegex(DeprecationWarning,
r'set the daemon attribute'):
t.setDaemon(True)
with self.assertWarnsRegex(DeprecationWarning,
r'get the name attribute'):
t.getName()
with self.assertWarnsRegex(DeprecationWarning,
r'set the name attribute'):
t.setName("name")
e = threading.Event()
with self.assertWarnsRegex(DeprecationWarning, 'use is_set()'):
e.isSet()
cond = threading.Condition()
cond.acquire()
with self.assertWarnsRegex(DeprecationWarning, 'use notify_all()'):
cond.notifyAll()
with self.assertWarnsRegex(DeprecationWarning, 'use active_count()'):
threading.activeCount()
with self.assertWarnsRegex(DeprecationWarning, 'use current_thread()'):
threading.currentThread()
def test_repr_daemon(self):
t = threading.Thread()
self.assertNotIn('daemon', repr(t))
t.daemon = True
self.assertIn('daemon', repr(t))
def test_daemon_param(self):
t = threading.Thread()
self.assertFalse(t.daemon)
t = threading.Thread(daemon=False)
self.assertFalse(t.daemon)
t = threading.Thread(daemon=True)
self.assertTrue(t.daemon)
@skip_unless_reliable_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, warnings
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()
with warnings.catch_warnings(record=True) as ws:
warnings.filterwarnings(
"always", category=DeprecationWarning)
if os.fork() == 0:
assert threading.active_count() == 1, threading.active_count()
os._exit(0)
else:
assert ws[0].category == DeprecationWarning, ws[0]
assert 'fork' in str(ws[0].message), ws[0]
os.wait()
"""
_, out, err = assert_python_ok("-c", code)
self.assertEqual(out, b'')
self.assertEqual(err, b'')
@skip_unless_reliable_fork
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.getswitchinterval()
self.addCleanup(sys.setswitchinterval, old_interval)
# Make the bug more likely to manifest.
test.support.setswitchinterval(1e-6)
for i in range(20):
t = threading.Thread(target=lambda: None)
t.start()
# Ignore the warning about fork with threads.
with warnings.catch_warnings(category=DeprecationWarning,
action="ignore"):
if (pid := os.fork()) == 0:
os._exit(11 if t.is_alive() else 10)
else:
t.join()
support.wait_process(pid, exitcode=10)
def test_main_thread(self):
main = threading.main_thread()
self.assertEqual(main.name, 'MainThread')
self.assertEqual(main.ident, threading.current_thread().ident)
self.assertEqual(main.ident, threading.get_ident())
def f():
self.assertNotEqual(threading.main_thread().ident,
threading.current_thread().ident)
th = threading.Thread(target=f)
th.start()
th.join()
@skip_unless_reliable_fork
@unittest.skipUnless(hasattr(os, 'waitpid'), "test needs os.waitpid()")
def test_main_thread_after_fork(self):
code = """if 1:
import os, threading
from test import support
ident = threading.get_ident()
pid = os.fork()
if pid == 0:
print("current ident", threading.get_ident() == ident)
main = threading.main_thread()
print("main", main.name)
print("main ident", main.ident == ident)
print("current is main", threading.current_thread() is main)
else:
support.wait_process(pid, exitcode=0)
"""
_, out, err = assert_python_ok("-c", code)
data = out.decode().replace('\r', '')
self.assertEqual(err, b"")
self.assertEqual(data,
"current ident True\n"
"main MainThread\n"
"main ident True\n"
"current is main True\n")
@skip_unless_reliable_fork
@unittest.skipUnless(hasattr(os, 'waitpid'), "test needs os.waitpid()")
def test_main_thread_after_fork_from_nonmain_thread(self):
code = """if 1:
import os, threading, sys, warnings
from test import support
def func():
ident = threading.get_ident()
with warnings.catch_warnings(record=True) as ws:
warnings.filterwarnings(
"always", category=DeprecationWarning)
pid = os.fork()
if pid == 0:
print("current ident", threading.get_ident() == ident)
main = threading.main_thread()
print("main", main.name, type(main).__name__)
print("main ident", main.ident == ident)
print("current is main", threading.current_thread() is main)
# stdout is fully buffered because not a tty,
# we have to flush before exit.
sys.stdout.flush()
else:
assert ws[0].category == DeprecationWarning, ws[0]
assert 'fork' in str(ws[0].message), ws[0]
support.wait_process(pid, exitcode=0)
th = threading.Thread(target=func)
th.start()
th.join()
"""
_, out, err = assert_python_ok("-c", code)
data = out.decode().replace('\r', '')
self.assertEqual(err.decode('utf-8'), "")
self.assertEqual(data,
"current ident True\n"
"main Thread-1 (func) Thread\n"
"main ident True\n"
"current is main True\n"
)
@skip_unless_reliable_fork
@unittest.skipUnless(hasattr(os, 'waitpid'), "test needs os.waitpid()")
def test_main_thread_after_fork_from_foreign_thread(self, create_dummy=False):
code = """if 1:
import os, threading, sys, traceback, _thread
from test import support
def func(lock):
ident = threading.get_ident()
if %s:
# call current_thread() before fork to allocate DummyThread
current = threading.current_thread()
print("current", current.name, type(current).__name__)
print("ident in _active", ident in threading._active)
# flush before fork, so child won't flush it again
sys.stdout.flush()
pid = os.fork()
if pid == 0:
print("current ident", threading.get_ident() == ident)
main = threading.main_thread()
print("main", main.name, type(main).__name__)
print("main ident", main.ident == ident)
print("current is main", threading.current_thread() is main)
print("_dangling", [t.name for t in list(threading._dangling)])
# stdout is fully buffered because not a tty,
# we have to flush before exit.
sys.stdout.flush()
try:
threading._shutdown()
os._exit(0)
except:
traceback.print_exc()
sys.stderr.flush()
os._exit(1)
else:
try:
support.wait_process(pid, exitcode=0)
except Exception:
# avoid 'could not acquire lock for
# <_io.BufferedWriter name='<stderr>'> at interpreter shutdown,'
traceback.print_exc()
sys.stderr.flush()
finally:
lock.release()
join_lock = _thread.allocate_lock()
join_lock.acquire()
th = _thread.start_new_thread(func, (join_lock,))
join_lock.acquire()
""" % create_dummy
# "DeprecationWarning: This process is multi-threaded, use of fork()
# may lead to deadlocks in the child"
_, out, err = assert_python_ok("-W", "ignore::DeprecationWarning", "-c", code)
data = out.decode().replace('\r', '')
self.assertEqual(err.decode(), "")
self.assertEqual(data,
("current Dummy-1 _DummyThread\n" if create_dummy else "") +
f"ident in _active {create_dummy!s}\n" +
"current ident True\n"
"main MainThread _MainThread\n"
"main ident True\n"
"current is main True\n"
"_dangling ['MainThread']\n")
def test_main_thread_after_fork_from_dummy_thread(self, create_dummy=False):
self.test_main_thread_after_fork_from_foreign_thread(create_dummy=True)
def test_main_thread_during_shutdown(self):
# bpo-31516: current_thread() should still point to the main thread
# at shutdown
code = """if 1:
import gc, threading
main_thread = threading.current_thread()
assert main_thread is threading.main_thread() # sanity check
class RefCycle:
def __init__(self):
self.cycle = self
def __del__(self):
print("GC:",
threading.current_thread() is main_thread,
threading.main_thread() is main_thread,
threading.enumerate() == [main_thread])
RefCycle()
gc.collect() # sanity check
x = RefCycle()
"""
_, out, err = assert_python_ok("-c", code)
data = out.decode()
self.assertEqual(err, b"")
self.assertEqual(data.splitlines(),
["GC: True True True"] * 2)
def test_finalization_shutdown(self):
# bpo-36402: Py_Finalize() calls threading._shutdown() which must wait
# until Python thread states of all non-daemon threads get deleted.
#
# Test similar to SubinterpThreadingTests.test_threads_join_2(), but
# test the finalization of the main interpreter.
code = """if 1:
import os
import threading
import time
import random
def random_sleep():
seconds = random.random() * 0.010
time.sleep(seconds)
class Sleeper:
def __del__(self):
random_sleep()
tls = threading.local()
def f():
# Sleep a bit so that the thread is still running when
# Py_Finalize() is called.
random_sleep()
tls.x = Sleeper()
random_sleep()
threading.Thread(target=f).start()
random_sleep()
"""
rc, out, err = assert_python_ok("-c", code)
self.assertEqual(err, b"")
def test_repr_stopped(self):
# Verify that "stopped" shows up in repr(Thread) appropriately.
started = _thread.allocate_lock()
finish = _thread.allocate_lock()
started.acquire()
finish.acquire()
def f():
started.release()
finish.acquire()
t = threading.Thread(target=f)
t.start()
started.acquire()
self.assertIn("started", repr(t))
finish.release()
# "stopped" should appear in the repr in a reasonable amount of time.
# Implementation detail: as of this writing, that's trivially true
# if .join() is called, and almost trivially true if .is_alive() is
# called. The detail we're testing here is that "stopped" shows up
# "all on its own".
LOOKING_FOR = "stopped"
for i in range(500):
if LOOKING_FOR in repr(t):
break
time.sleep(0.01)
self.assertIn(LOOKING_FOR, repr(t)) # we waited at least 5 seconds
t.join()
def test_BoundedSemaphore_limit(self):
# BoundedSemaphore should raise ValueError if released too often.
for limit in range(1, 10):
bs = threading.BoundedSemaphore(limit)
threads = [threading.Thread(target=bs.acquire)
for _ in range(limit)]
for t in threads:
t.start()
for t in threads:
t.join()
threads = [threading.Thread(target=bs.release)
for _ in range(limit)]
for t in threads:
t.start()
for t in threads:
t.join()
self.assertRaises(ValueError, bs.release)
@cpython_only
def test_frame_tstate_tracing(self):
_testcapi = import_module("_testcapi")
# Issue #14432: Crash when a generator is created in a C thread that is
# destroyed while the generator is still used. The issue was that a
# generator contains a frame, and the frame kept a reference to the
# Python state of the destroyed C thread. The crash occurs when a trace
# function is setup.
def noop_trace(frame, event, arg):
# no operation
return noop_trace
def generator():
while 1:
yield "generator"
def callback():
if callback.gen is None:
callback.gen = generator()
return next(callback.gen)
callback.gen = None
old_trace = sys.gettrace()
sys.settrace(noop_trace)
try:
# Install a trace function
threading.settrace(noop_trace)
# Create a generator in a C thread which exits after the call
_testcapi.call_in_temporary_c_thread(callback)
# Call the generator in a different Python thread, check that the
# generator didn't keep a reference to the destroyed thread state
for test in range(3):
# The trace function is still called here