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5e8dc97a09
Fixes Issue #874900: after an os.fork() call the threading module state is cleaned up in the child process to prevent deadlock and report proper thread counts if the new process uses the threading module.
304 lines
9.8 KiB
Python
304 lines
9.8 KiB
Python
# Very rudimentary test of threading module
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import test.test_support
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from test.test_support import verbose
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import random
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import sys
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import threading
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import thread
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import time
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import unittest
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# A trivial mutable counter.
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class Counter(object):
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def __init__(self):
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self.value = 0
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def inc(self):
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self.value += 1
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def dec(self):
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self.value -= 1
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def get(self):
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return self.value
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class TestThread(threading.Thread):
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def __init__(self, name, testcase, sema, mutex, nrunning):
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threading.Thread.__init__(self, name=name)
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self.testcase = testcase
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self.sema = sema
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self.mutex = mutex
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self.nrunning = nrunning
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def run(self):
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delay = random.random() * 2
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if verbose:
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print 'task', self.getName(), 'will run for', delay, 'sec'
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self.sema.acquire()
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self.mutex.acquire()
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self.nrunning.inc()
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if verbose:
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print self.nrunning.get(), 'tasks are running'
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self.testcase.assert_(self.nrunning.get() <= 3)
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self.mutex.release()
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time.sleep(delay)
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if verbose:
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print 'task', self.getName(), 'done'
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self.mutex.acquire()
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self.nrunning.dec()
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self.testcase.assert_(self.nrunning.get() >= 0)
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if verbose:
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print self.getName(), 'is finished.', self.nrunning.get(), \
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'tasks are running'
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self.mutex.release()
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self.sema.release()
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class ThreadTests(unittest.TestCase):
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# Create a bunch of threads, let each do some work, wait until all are
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# done.
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def test_various_ops(self):
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# This takes about n/3 seconds to run (about n/3 clumps of tasks,
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# times about 1 second per clump).
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NUMTASKS = 10
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# no more than 3 of the 10 can run at once
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sema = threading.BoundedSemaphore(value=3)
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mutex = threading.RLock()
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numrunning = Counter()
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threads = []
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for i in range(NUMTASKS):
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t = TestThread("<thread %d>"%i, self, sema, mutex, numrunning)
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threads.append(t)
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t.start()
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if verbose:
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print 'waiting for all tasks to complete'
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for t in threads:
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t.join(NUMTASKS)
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self.assert_(not t.isAlive())
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if verbose:
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print 'all tasks done'
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self.assertEqual(numrunning.get(), 0)
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# run with a small(ish) thread stack size (256kB)
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def test_various_ops_small_stack(self):
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if verbose:
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print 'with 256kB thread stack size...'
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try:
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threading.stack_size(262144)
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except thread.error:
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if verbose:
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print 'platform does not support changing thread stack size'
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return
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self.test_various_ops()
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threading.stack_size(0)
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# run with a large thread stack size (1MB)
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def test_various_ops_large_stack(self):
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if verbose:
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print 'with 1MB thread stack size...'
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try:
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threading.stack_size(0x100000)
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except thread.error:
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if verbose:
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print 'platform does not support changing thread stack size'
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return
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self.test_various_ops()
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threading.stack_size(0)
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def test_foreign_thread(self):
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# Check that a "foreign" thread can use the threading module.
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def f(mutex):
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# Acquiring an RLock forces an entry for the foreign
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# thread to get made in the threading._active map.
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r = threading.RLock()
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r.acquire()
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r.release()
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mutex.release()
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mutex = threading.Lock()
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mutex.acquire()
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tid = thread.start_new_thread(f, (mutex,))
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# Wait for the thread to finish.
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mutex.acquire()
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self.assert_(tid in threading._active)
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self.assert_(isinstance(threading._active[tid],
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threading._DummyThread))
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del threading._active[tid]
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# PyThreadState_SetAsyncExc() is a CPython-only gimmick, not (currently)
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# exposed at the Python level. This test relies on ctypes to get at it.
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def test_PyThreadState_SetAsyncExc(self):
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try:
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import ctypes
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except ImportError:
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if verbose:
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print "test_PyThreadState_SetAsyncExc can't import ctypes"
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return # can't do anything
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set_async_exc = ctypes.pythonapi.PyThreadState_SetAsyncExc
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class AsyncExc(Exception):
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pass
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exception = ctypes.py_object(AsyncExc)
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# `worker_started` is set by the thread when it's inside a try/except
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# block waiting to catch the asynchronously set AsyncExc exception.
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# `worker_saw_exception` is set by the thread upon catching that
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# exception.
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worker_started = threading.Event()
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worker_saw_exception = threading.Event()
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class Worker(threading.Thread):
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def run(self):
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self.id = thread.get_ident()
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self.finished = False
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try:
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while True:
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worker_started.set()
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time.sleep(0.1)
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except AsyncExc:
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self.finished = True
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worker_saw_exception.set()
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t = Worker()
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t.setDaemon(True) # so if this fails, we don't hang Python at shutdown
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t.start()
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if verbose:
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print " started worker thread"
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# Try a thread id that doesn't make sense.
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if verbose:
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print " trying nonsensical thread id"
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result = set_async_exc(ctypes.c_long(-1), exception)
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self.assertEqual(result, 0) # no thread states modified
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# Now raise an exception in the worker thread.
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if verbose:
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print " waiting for worker thread to get started"
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worker_started.wait()
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if verbose:
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print " verifying worker hasn't exited"
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self.assert_(not t.finished)
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if verbose:
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print " attempting to raise asynch exception in worker"
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result = set_async_exc(ctypes.c_long(t.id), exception)
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self.assertEqual(result, 1) # one thread state modified
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if verbose:
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print " waiting for worker to say it caught the exception"
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worker_saw_exception.wait(timeout=10)
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self.assert_(t.finished)
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if verbose:
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print " all OK -- joining worker"
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if t.finished:
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t.join()
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# else the thread is still running, and we have no way to kill it
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def test_enumerate_after_join(self):
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# Try hard to trigger #1703448: a thread is still returned in
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# threading.enumerate() after it has been join()ed.
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enum = threading.enumerate
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old_interval = sys.getcheckinterval()
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sys.setcheckinterval(1)
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try:
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for i in xrange(1, 1000):
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t = threading.Thread(target=lambda: None)
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t.start()
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t.join()
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l = enum()
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self.assertFalse(t in l,
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"#1703448 triggered after %d trials: %s" % (i, l))
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finally:
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sys.setcheckinterval(old_interval)
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class ThreadJoinOnShutdown(unittest.TestCase):
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def _run_and_join(self, script):
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script = """if 1:
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import sys, os, time, threading
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# a thread, which waits for the main program to terminate
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def joiningfunc(mainthread):
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mainthread.join()
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print 'end of thread'
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\n""" + script
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import subprocess
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p = subprocess.Popen([sys.executable, "-c", script], stdout=subprocess.PIPE)
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rc = p.wait()
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self.assertEqual(p.stdout.read(), "end of main\nend of thread\n")
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self.failIf(rc == 2, "interpreter was blocked")
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self.failUnless(rc == 0, "Unexpected error")
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def test_1_join_on_shutdown(self):
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# The usual case: on exit, wait for a non-daemon thread
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script = """if 1:
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import os
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t = threading.Thread(target=joiningfunc,
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args=(threading.currentThread(),))
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t.start()
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time.sleep(0.1)
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print 'end of main'
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"""
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self._run_and_join(script)
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def test_2_join_in_forked_process(self):
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# Like the test above, but from a forked interpreter
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import os
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if not hasattr(os, 'fork'):
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return
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script = """if 1:
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childpid = os.fork()
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if childpid != 0:
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os.waitpid(childpid, 0)
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sys.exit(0)
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t = threading.Thread(target=joiningfunc,
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args=(threading.currentThread(),))
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t.start()
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print 'end of main'
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"""
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self._run_and_join(script)
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def test_3_join_in_forked_from_thread(self):
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# Like the test above, but fork() was called from a worker thread
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# In the forked process, the main Thread object must be marked as stopped.
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import os
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if not hasattr(os, 'fork'):
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return
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script = """if 1:
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main_thread = threading.currentThread()
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def worker():
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childpid = os.fork()
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if childpid != 0:
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os.waitpid(childpid, 0)
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sys.exit(0)
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t = threading.Thread(target=joiningfunc,
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args=(main_thread,))
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print 'end of main'
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t.start()
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t.join() # Should not block: main_thread is already stopped
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w = threading.Thread(target=worker)
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w.start()
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"""
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self._run_and_join(script)
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def test_main():
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test.test_support.run_unittest(ThreadTests,
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ThreadJoinOnShutdown)
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if __name__ == "__main__":
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test_main()
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