Lib/test/test_threading.py

   1 # Very rudimentary test of threading module
   2
   3 import test.test_support
   4 from test.test_support import verbose
   5 import random
   6 import re
   7 import sys
   8 thread = test.test_support.import_module('thread')
   9 threading = test.test_support.import_module('threading')
  10 import time
  11 import unittest
  12 import weakref
  13
  14 from test import lock_tests
  15
  16 # A trivial mutable counter.
  17 class Counter(object):
  18     def __init__(self):
  19         self.value = 0
  20     def inc(self):
  21         self.value += 1
  22     def dec(self):
  23         self.value -= 1
  24     def get(self):
  25         return self.value
  26
  27 class TestThread(threading.Thread):
  28     def __init__(self, name, testcase, sema, mutex, nrunning):
  29         threading.Thread.__init__(self, name=name)
  30         self.testcase = testcase
  31         self.sema = sema
  32         self.mutex = mutex
  33         self.nrunning = nrunning
  34
  35     def run(self):
  36         delay = random.random() / 10000.0
  37         if verbose:
  38             print 'task %s will run for %.1f usec' % (
  39                 self.name, delay * 1e6)
  40
  41         with self.sema:
  42             with self.mutex:
  43                 self.nrunning.inc()
  44                 if verbose:
  45                     print self.nrunning.get(), 'tasks are running'
  46                 self.testcase.assertTrue(self.nrunning.get() <= 3)
  47
  48             time.sleep(delay)
  49             if verbose:
  50                 print 'task', self.name, 'done'
  51
  52             with self.mutex:
  53                 self.nrunning.dec()
  54                 self.testcase.assertTrue(self.nrunning.get() >= 0)
  55                 if verbose:
  56                     print '%s is finished. %d tasks are running' % (
  57                         self.name, self.nrunning.get())
  58
  59 class BaseTestCase(unittest.TestCase):
  60     def setUp(self):
  61         self._threads = test.test_support.threading_setup()
  62
  63     def tearDown(self):
  64         test.test_support.threading_cleanup(*self._threads)
  65         test.test_support.reap_children()
  66
  67
  68 class ThreadTests(BaseTestCase):
  69
  70     # Create a bunch of threads, let each do some work, wait until all are
  71     # done.
  72     def test_various_ops(self):
  73         # This takes about n/3 seconds to run (about n/3 clumps of tasks,
  74         # times about 1 second per clump).
  75         NUMTASKS = 10
  76
  77         # no more than 3 of the 10 can run at once
  78         sema = threading.BoundedSemaphore(value=3)
  79         mutex = threading.RLock()
  80         numrunning = Counter()
  81
  82         threads = []
  83
  84         for i in range(NUMTASKS):
  85             t = TestThread("<thread %d>"%i, self, sema, mutex, numrunning)
  86             threads.append(t)
  87             self.assertEqual(t.ident, None)
  88             self.assertTrue(re.match('<TestThread\(.*, initial\)>', repr(t)))
  89             t.start()
  90
  91         if verbose:
  92             print 'waiting for all tasks to complete'
  93         for t in threads:
  94             t.join(NUMTASKS)
  95             self.assertTrue(not t.is_alive())
  96             self.assertNotEqual(t.ident, 0)
  97             self.assertFalse(t.ident is None)
  98             self.assertTrue(re.match('<TestThread\(.*, \w+ -?\d+\)>', repr(t)))
  99         if verbose:
 100             print 'all tasks done'
 101         self.assertEqual(numrunning.get(), 0)
 102
 103     def test_ident_of_no_threading_threads(self):
 104         # The ident still must work for the main thread and dummy threads.
 105         self.assertFalse(threading.currentThread().ident is None)
 106         def f():
 107             ident.append(threading.currentThread().ident)
 108             done.set()
 109         done = threading.Event()
 110         ident = []
 111         thread.start_new_thread(f, ())
 112         done.wait()
 113         self.assertFalse(ident[0] is None)
 114         # Kill the "immortal" _DummyThread
 115         del threading._active[ident[0]]
 116
 117     # run with a small(ish) thread stack size (256kB)
 118     def test_various_ops_small_stack(self):
 119         if verbose:
 120             print 'with 256kB thread stack size...'
 121         try:
 122             threading.stack_size(262144)
 123         except thread.error:
 124             if verbose:
 125                 print 'platform does not support changing thread stack size'
 126             return
 127         self.test_various_ops()
 128         threading.stack_size(0)
 129
 130     # run with a large thread stack size (1MB)
 131     def test_various_ops_large_stack(self):
 132         if verbose:
 133             print 'with 1MB thread stack size...'
 134         try:
 135             threading.stack_size(0x100000)
 136         except thread.error:
 137             if verbose:
 138                 print 'platform does not support changing thread stack size'
 139             return
 140         self.test_various_ops()
 141         threading.stack_size(0)
 142
 143     def test_foreign_thread(self):
 144         # Check that a "foreign" thread can use the threading module.
 145         def f(mutex):
 146             # Calling current_thread() forces an entry for the foreign
 147             # thread to get made in the threading._active map.
 148             threading.current_thread()
 149             mutex.release()
 150
 151         mutex = threading.Lock()
 152         mutex.acquire()
 153         tid = thread.start_new_thread(f, (mutex,))
 154         # Wait for the thread to finish.
 155         mutex.acquire()
 156         self.assertIn(tid, threading._active)
 157         self.assertIsInstance(threading._active[tid], threading._DummyThread)
 158         del threading._active[tid]
 159
 160     # PyThreadState_SetAsyncExc() is a CPython-only gimmick, not (currently)
 161     # exposed at the Python level.  This test relies on ctypes to get at it.
 162     def test_PyThreadState_SetAsyncExc(self):
 163         try:
 164             import ctypes
 165         except ImportError:
 166             if verbose:
 167                 print "test_PyThreadState_SetAsyncExc can't import ctypes"
 168             return  # can't do anything
 169
 170         set_async_exc = ctypes.pythonapi.PyThreadState_SetAsyncExc
 171
 172         class AsyncExc(Exception):
 173             pass
 174
 175         exception = ctypes.py_object(AsyncExc)
 176
 177         # First check it works when setting the exception from the same thread.
 178         tid = thread.get_ident()
 179
 180         try:
 181             result = set_async_exc(ctypes.c_long(tid), exception)
 182             # The exception is async, so we might have to keep the VM busy until
 183             # it notices.
 184             while True:
 185                 pass
 186         except AsyncExc:
 187             pass
 188         else:
 189             # This code is unreachable but it reflects the intent. If we wanted
 190             # to be smarter the above loop wouldn't be infinite.
 191             self.fail("AsyncExc not raised")
 192         try:
 193             self.assertEqual(result, 1) # one thread state modified
 194         except UnboundLocalError:
 195             # The exception was raised too quickly for us to get the result.
 196             pass
 197
 198         # `worker_started` is set by the thread when it's inside a try/except
 199         # block waiting to catch the asynchronously set AsyncExc exception.
 200         # `worker_saw_exception` is set by the thread upon catching that
 201         # exception.
 202         worker_started = threading.Event()
 203         worker_saw_exception = threading.Event()
 204
 205         class Worker(threading.Thread):
 206             def run(self):
 207                 self.id = thread.get_ident()
 208                 self.finished = False
 209
 210                 try:
 211                     while True:
 212                         worker_started.set()
 213                         time.sleep(0.1)
 214                 except AsyncExc:
 215                     self.finished = True
 216                     worker_saw_exception.set()
 217
 218         t = Worker()
 219         t.daemon = True # so if this fails, we don't hang Python at shutdown
 220         t.start()
 221         if verbose:
 222             print "    started worker thread"
 223
 224         # Try a thread id that doesn't make sense.
 225         if verbose:
 226             print "    trying nonsensical thread id"
 227         result = set_async_exc(ctypes.c_long(-1), exception)
 228         self.assertEqual(result, 0)  # no thread states modified
 229
 230         # Now raise an exception in the worker thread.
 231         if verbose:
 232             print "    waiting for worker thread to get started"
 233         ret = worker_started.wait()
 234         self.assertTrue(ret)
 235         if verbose:
 236             print "    verifying worker hasn't exited"
 237         self.assertTrue(not t.finished)
 238         if verbose:
 239             print "    attempting to raise asynch exception in worker"
 240         result = set_async_exc(ctypes.c_long(t.id), exception)
 241         self.assertEqual(result, 1) # one thread state modified
 242         if verbose:
 243             print "    waiting for worker to say it caught the exception"
 244         worker_saw_exception.wait(timeout=10)
 245         self.assertTrue(t.finished)
 246         if verbose:
 247             print "    all OK -- joining worker"
 248         if t.finished:
 249             t.join()
 250         # else the thread is still running, and we have no way to kill it
 251
 252     def test_limbo_cleanup(self):
 253         # Issue 7481: Failure to start thread should cleanup the limbo map.
 254         def fail_new_thread(*args):
 255             raise thread.error()
 256         _start_new_thread = threading._start_new_thread
 257         threading._start_new_thread = fail_new_thread
 258         try:
 259             t = threading.Thread(target=lambda: None)
 260             self.assertRaises(thread.error, t.start)
 261             self.assertFalse(
 262                 t in threading._limbo,
 263                 "Failed to cleanup _limbo map on failure of Thread.start().")
 264         finally:
 265             threading._start_new_thread = _start_new_thread
 266
 267     def test_finalize_runnning_thread(self):
 268         # Issue 1402: the PyGILState_Ensure / _Release functions may be called
 269         # very late on python exit: on deallocation of a running thread for
 270         # example.
 271         try:
 272             import ctypes
 273         except ImportError:
 274             if verbose:
 275                 print("test_finalize_with_runnning_thread can't import ctypes")
 276             return  # can't do anything
 277
 278         import subprocess
 279         rc = subprocess.call([sys.executable, "-c", """if 1:
 280             import ctypes, sys, time, thread
 281
 282             # This lock is used as a simple event variable.
 283             ready = thread.allocate_lock()
 284             ready.acquire()
 285
 286             # Module globals are cleared before __del__ is run
 287             # So we save the functions in class dict
 288             class C:
 289                 ensure = ctypes.pythonapi.PyGILState_Ensure
 290                 release = ctypes.pythonapi.PyGILState_Release
 291                 def __del__(self):
 292                     state = self.ensure()
 293                     self.release(state)
 294
 295             def waitingThread():
 296                 x = C()
 297                 ready.release()
 298                 time.sleep(100)
 299
 300             thread.start_new_thread(waitingThread, ())
 301             ready.acquire()  # Be sure the other thread is waiting.
 302             sys.exit(42)
 303             """])
 304         self.assertEqual(rc, 42)
 305
 306     def test_finalize_with_trace(self):
 307         # Issue1733757
 308         # Avoid a deadlock when sys.settrace steps into threading._shutdown
 309         import subprocess
 310         rc = subprocess.call([sys.executable, "-c", """if 1:
 311             import sys, threading
 312
 313             # A deadlock-killer, to prevent the
 314             # testsuite to hang forever
 315             def killer():
 316                 import os, time
 317                 time.sleep(2)
 318                 print 'program blocked; aborting'
 319                 os._exit(2)
 320             t = threading.Thread(target=killer)
 321             t.daemon = True
 322             t.start()
 323
 324             # This is the trace function
 325             def func(frame, event, arg):
 326                 threading.current_thread()
 327                 return func
 328
 329             sys.settrace(func)
 330             """])
 331         self.assertFalse(rc == 2, "interpreted was blocked")
 332         self.assertTrue(rc == 0, "Unexpected error")
 333
 334     def test_join_nondaemon_on_shutdown(self):
 335         # Issue 1722344
 336         # Raising SystemExit skipped threading._shutdown
 337         import subprocess
 338         p = subprocess.Popen([sys.executable, "-c", """if 1:
 339                 import threading
 340                 from time import sleep
 341
 342                 def child():
 343                     sleep(1)
 344                     # As a non-daemon thread we SHOULD wake up and nothing
 345                     # should be torn down yet
 346                     print "Woke up, sleep function is:", sleep
 347
 348                 threading.Thread(target=child).start()
 349                 raise SystemExit
 350             """],
 351             stdout=subprocess.PIPE,
 352             stderr=subprocess.PIPE)
 353         stdout, stderr = p.communicate()
 354         self.assertEqual(stdout.strip(),
 355             "Woke up, sleep function is: <built-in function sleep>")
 356         stderr = re.sub(r"^\[\d+ refs\]", "", stderr, re.MULTILINE).strip()
 357         self.assertEqual(stderr, "")
 358
 359     def test_enumerate_after_join(self):
 360         # Try hard to trigger #1703448: a thread is still returned in
 361         # threading.enumerate() after it has been join()ed.
 362         enum = threading.enumerate
 363         old_interval = sys.getcheckinterval()
 364         try:
 365             for i in xrange(1, 100):
 366                 # Try a couple times at each thread-switching interval
 367                 # to get more interleavings.
 368                 sys.setcheckinterval(i // 5)
 369                 t = threading.Thread(target=lambda: None)
 370                 t.start()
 371                 t.join()
 372                 l = enum()
 373                 self.assertNotIn(t, l,
 374                     "#1703448 triggered after %d trials: %s" % (i, l))
 375         finally:
 376             sys.setcheckinterval(old_interval)
 377
 378     def test_no_refcycle_through_target(self):
 379         class RunSelfFunction(object):
 380             def __init__(self, should_raise):
 381                 # The links in this refcycle from Thread back to self
 382                 # should be cleaned up when the thread completes.
 383                 self.should_raise = should_raise
 384                 self.thread = threading.Thread(target=self._run,
 385                                                args=(self,),
 386                                                kwargs={'yet_another':self})
 387                 self.thread.start()
 388
 389             def _run(self, other_ref, yet_another):
 390                 if self.should_raise:
 391                     raise SystemExit
 392
 393         cyclic_object = RunSelfFunction(should_raise=False)
 394         weak_cyclic_object = weakref.ref(cyclic_object)
 395         cyclic_object.thread.join()
 396         del cyclic_object
 397         self.assertEquals(None, weak_cyclic_object(),
 398                           msg=('%d references still around' %
 399                                sys.getrefcount(weak_cyclic_object())))
 400
 401         raising_cyclic_object = RunSelfFunction(should_raise=True)
 402         weak_raising_cyclic_object = weakref.ref(raising_cyclic_object)
 403         raising_cyclic_object.thread.join()
 404         del raising_cyclic_object
 405         self.assertEquals(None, weak_raising_cyclic_object(),
 406                           msg=('%d references still around' %
 407                                sys.getrefcount(weak_raising_cyclic_object())))
 408
 409
 410 class ThreadJoinOnShutdown(BaseTestCase):
 411
 412     def _run_and_join(self, script):
 413         script = """if 1:
 414             import sys, os, time, threading
 415
 416             # a thread, which waits for the main program to terminate
 417             def joiningfunc(mainthread):
 418                 mainthread.join()
 419                 print 'end of thread'
 420         \n""" + script
 421
 422         import subprocess
 423         p = subprocess.Popen([sys.executable, "-c", script], stdout=subprocess.PIPE)
 424         rc = p.wait()
 425         data = p.stdout.read().replace('\r', '')
 426         self.assertEqual(data, "end of main\nend of thread\n")
 427         self.assertFalse(rc == 2, "interpreter was blocked")
 428         self.assertTrue(rc == 0, "Unexpected error")
 429
 430     def test_1_join_on_shutdown(self):
 431         # The usual case: on exit, wait for a non-daemon thread
 432         script = """if 1:
 433             import os
 434             t = threading.Thread(target=joiningfunc,
 435                                  args=(threading.current_thread(),))
 436             t.start()
 437             time.sleep(0.1)
 438             print 'end of main'
 439             """
 440         self._run_and_join(script)
 441
 442
 443     def test_2_join_in_forked_process(self):
 444         # Like the test above, but from a forked interpreter
 445         import os
 446         if not hasattr(os, 'fork'):
 447             return
 448         script = """if 1:
 449             childpid = os.fork()
 450             if childpid != 0:
 451                 os.waitpid(childpid, 0)
 452                 sys.exit(0)
 453
 454             t = threading.Thread(target=joiningfunc,
 455                                  args=(threading.current_thread(),))
 456             t.start()
 457             print 'end of main'
 458             """
 459         self._run_and_join(script)
 460
 461     def test_3_join_in_forked_from_thread(self):
 462         # Like the test above, but fork() was called from a worker thread
 463         # In the forked process, the main Thread object must be marked as stopped.
 464         import os
 465         if not hasattr(os, 'fork'):
 466             return
 467         # Skip platforms with known problems forking from a worker thread.
 468         # See http://bugs.python.org/issue3863.
 469         if sys.platform in ('freebsd4', 'freebsd5', 'freebsd6', 'os2emx'):
 470             print >>sys.stderr, ('Skipping test_3_join_in_forked_from_thread'
 471                                  ' due to known OS bugs on'), sys.platform
 472             return
 473         script = """if 1:
 474             main_thread = threading.current_thread()
 475             def worker():
 476                 childpid = os.fork()
 477                 if childpid != 0:
 478                     os.waitpid(childpid, 0)
 479                     sys.exit(0)
 480
 481                 t = threading.Thread(target=joiningfunc,
 482                                      args=(main_thread,))
 483                 print 'end of main'
 484                 t.start()
 485                 t.join() # Should not block: main_thread is already stopped
 486
 487             w = threading.Thread(target=worker)
 488             w.start()
 489             """
 490         self._run_and_join(script)
 491
 492
 493 class ThreadingExceptionTests(BaseTestCase):
 494     # A RuntimeError should be raised if Thread.start() is called
 495     # multiple times.
 496     def test_start_thread_again(self):
 497         thread = threading.Thread()
 498         thread.start()
 499         self.assertRaises(RuntimeError, thread.start)
 500
 501     def test_joining_current_thread(self):
 502         current_thread = threading.current_thread()
 503         self.assertRaises(RuntimeError, current_thread.join);
 504
 505     def test_joining_inactive_thread(self):
 506         thread = threading.Thread()
 507         self.assertRaises(RuntimeError, thread.join)
 508
 509     def test_daemonize_active_thread(self):
 510         thread = threading.Thread()
 511         thread.start()
 512         self.assertRaises(RuntimeError, setattr, thread, "daemon", True)
 513
 514
 515 class LockTests(lock_tests.LockTests):
 516     locktype = staticmethod(threading.Lock)
 517
 518 class RLockTests(lock_tests.RLockTests):
 519     locktype = staticmethod(threading.RLock)
 520
 521 class EventTests(lock_tests.EventTests):
 522     eventtype = staticmethod(threading.Event)
 523
 524 class ConditionAsRLockTests(lock_tests.RLockTests):
 525     # An Condition uses an RLock by default and exports its API.
 526     locktype = staticmethod(threading.Condition)
 527
 528 class ConditionTests(lock_tests.ConditionTests):
 529     condtype = staticmethod(threading.Condition)
 530
 531 class SemaphoreTests(lock_tests.SemaphoreTests):
 532     semtype = staticmethod(threading.Semaphore)
 533
 534 class BoundedSemaphoreTests(lock_tests.BoundedSemaphoreTests):
 535     semtype = staticmethod(threading.BoundedSemaphore)
 536
 537
 538 def test_main():
 539     test.test_support.run_unittest(LockTests, RLockTests, EventTests,
 540                                    ConditionAsRLockTests, ConditionTests,
 541                                    SemaphoreTests, BoundedSemaphoreTests,
 542                                    ThreadTests,
 543                                    ThreadJoinOnShutdown,
 544                                    ThreadingExceptionTests,
 545                                    )
 546
 547 if __name__ == "__main__":
 548     test_main()