Migrate threading functions and class to helper

fanninpm · fanninpm · commit ef1048757e1d · 2022-02-13T17:27:07.000-05:00
diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
@@ -104,8 +104,6 @@
     'temp_umask', "reap_children",
     # logging
     "TestHandler",
-    # threads
-    "threading_setup", "threading_cleanup", "reap_threads", "start_threads",
     # miscellaneous
     "check_warnings", "check_no_resource_warning", "check_no_warnings",
     "EnvironmentVarGuard",
@@ -1541,104 +1539,6 @@ def print_warning(msg):
 # to cleanup threads.
 environment_altered = False
 
-# NOTE: we use thread._count() rather than threading.enumerate() (or the
-# moral equivalent thereof) because a threading.Thread object is still alive
-# until its __bootstrap() method has returned, even after it has been
-# unregistered from the threading module.
-# thread._count(), on the other hand, only gets decremented *after* the
-# __bootstrap() method has returned, which gives us reliable reference counts
-# at the end of a test run.
-
-def threading_setup():
-    return _thread._count(), threading._dangling.copy()
-
-def threading_cleanup(*original_values):
-    global environment_altered
-
-    _MAX_COUNT = 100
-
-    for count in range(_MAX_COUNT):
-        values = _thread._count(), threading._dangling
-        if values == original_values:
-            break
-
-        if not count: # Display a warning at the first iteration
-            environment_altered = True
-            dangling_threads = values[1]
-            print_warning(f"threading_cleanup() failed to cleanup "
-                          f"{values[0] - original_values[0]} threads "
-                          f"(count: {values[0]}, "
-                          f"dangling: {len(dangling_threads)})")
-            for thread in dangling_threads:
-                print_warning(f"Dangling thread: {thread!r}")
-
-            # Don't hold references to threads
-            dangling_threads = None
-        values = None
-
-        time.sleep(0.01)
-        gc_collect()
-
-
-def reap_threads(func):
-    """Use this function when threads are being used.  This will
-    ensure that the threads are cleaned up even when the test fails.
-    """
-    @functools.wraps(func)
-    def decorator(*args):
-        key = threading_setup()
-        try:
-            return func(*args)
-        finally:
-            threading_cleanup(*key)
-    return decorator
-
-
-@contextlib.contextmanager
-def wait_threads_exit(timeout=60.0):
-    """
-    bpo-31234: Context manager to wait until all threads created in the with
-    statement exit.
-
-    Use _thread.count() to check if threads exited. Indirectly, wait until
-    threads exit the internal t_bootstrap() C function of the _thread module.
-
-    threading_setup() and threading_cleanup() are designed to emit a warning
-    if a test leaves running threads in the background. This context manager
-    is designed to cleanup threads started by the _thread.start_new_thread()
-    which doesn't allow to wait for thread exit, whereas thread.Thread has a
-    join() method.
-    """
-    old_count = _thread._count()
-    try:
-        yield
-    finally:
-        start_time = time.monotonic()
-        deadline = start_time + timeout
-        while True:
-            count = _thread._count()
-            if count <= old_count:
-                break
-            if time.monotonic() > deadline:
-                dt = time.monotonic() - start_time
-                msg = (f"wait_threads() failed to cleanup {count - old_count} "
-                       f"threads after {dt:.1f} seconds "
-                       f"(count: {count}, old count: {old_count})")
-                raise AssertionError(msg)
-            time.sleep(0.010)
-            gc_collect()
-
-
-def join_thread(thread, timeout=30.0):
-    """Join a thread. Raise an AssertionError if the thread is still alive
-    after timeout seconds.
-    """
-    thread.join(timeout)
-    if thread.is_alive():
-        msg = f"failed to join the thread in {timeout:.1f} seconds"
-        raise AssertionError(msg)
-
-
 def reap_children():
     """Use this function at the end of test_main() whenever sub-processes
     are started.  This will help ensure that no extra children (zombies)
@@ -1667,42 +1567,6 @@ def reap_children():
         environment_altered = True
 
 
-@contextlib.contextmanager
-def start_threads(threads, unlock=None):
-    threads = list(threads)
-    started = []
-    try:
-        try:
-            for t in threads:
-                t.start()
-                started.append(t)
-        except:
-            if verbose:
-                print("Can't start %d threads, only %d threads started" %
-                      (len(threads), len(started)))
-            raise
-        yield
-    finally:
-        try:
-            if unlock:
-                unlock()
-            endtime = starttime = time.monotonic()
-            for timeout in range(1, 16):
-                endtime += 60
-                for t in started:
-                    t.join(max(endtime - time.monotonic(), 0.01))
-                started = [t for t in started if t.is_alive()]
-                if not started:
-                    break
-                if verbose:
-                    print('Unable to join %d threads during a period of '
-                          '%d minutes' % (len(started), timeout))
-        finally:
-            started = [t for t in started if t.is_alive()]
-            if started:
-                faulthandler.dump_traceback(sys.stdout)
-                raise AssertionError('Unable to join %d threads' % len(started))
-
 @contextlib.contextmanager
 def swap_attr(obj, attr, new_val):
     """Temporary swap out an attribute with a new object.
@@ -2507,63 +2371,6 @@ def __exit__(self, *exc_info):
         del self.unraisable
 
 
-class catch_threading_exception:
-    """
-    Context manager catching threading.Thread exception using
-    threading.excepthook.
-
-    Attributes set when an exception is catched:
-
-    * exc_type
-    * exc_value
-    * exc_traceback
-    * thread
-
-    See threading.excepthook() documentation for these attributes.
-
-    These attributes are deleted at the context manager exit.
-
-    Usage:
-
-        with support.catch_threading_exception() as cm:
-            # code spawning a thread which raises an exception
-            ...
-
-            # check the thread exception, use cm attributes:
-            # exc_type, exc_value, exc_traceback, thread
-            ...
-
-        # exc_type, exc_value, exc_traceback, thread attributes of cm no longer
-        # exists at this point
-        # (to avoid reference cycles)
-    """
-
-    def __init__(self):
-        self.exc_type = None
-        self.exc_value = None
-        self.exc_traceback = None
-        self.thread = None
-        self._old_hook = None
-
-    def _hook(self, args):
-        self.exc_type = args.exc_type
-        self.exc_value = args.exc_value
-        self.exc_traceback = args.exc_traceback
-        self.thread = args.thread
-
-    def __enter__(self):
-        self._old_hook = threading.excepthook
-        threading.excepthook = self._hook
-        return self
-
-    def __exit__(self, *exc_info):
-        threading.excepthook = self._old_hook
-        del self.exc_type
-        del self.exc_value
-        del self.exc_traceback
-        del self.thread
-
-
 def wait_process(pid, *, exitcode, timeout=None):
     """
     Wait until process pid completes and check that the process exit code is
