From: Ben Darnell <ben@bendarnell.com>
Date: Sun, 31 Dec 2017 22:05:05 +0000 (-0500)
Subject: asyncio: Don't raise "IOLoop is closing" in add_callback
X-Git-Tag: v5.0.0~22^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=207ff24d273195043cc8d8e874da890160619b90;p=thirdparty%2Ftornado.git

asyncio: Don't raise "IOLoop is closing" in add_callback

This mirrors a previous change to PollIOLoop. Fix a test that had
rotted and become meaningless.

Fixes #2191
---

diff --git a/tornado/platform/asyncio.py b/tornado/platform/asyncio.py
index adc7c1aeb..42c8a8001 100644
--- a/tornado/platform/asyncio.py
+++ b/tornado/platform/asyncio.py
@@ -130,13 +130,17 @@ class BaseAsyncIOLoop(IOLoop):
         timeout.cancel()
 
     def add_callback(self, callback, *args, **kwargs):
-        if self.closing:
-            # TODO: this is racy; we need a lock to ensure that the
-            # loop isn't closed during call_soon_threadsafe.
-            raise RuntimeError("IOLoop is closing")
-        self.asyncio_loop.call_soon_threadsafe(
-            self._run_callback,
-            functools.partial(stack_context.wrap(callback), *args, **kwargs))
+        try:
+            self.asyncio_loop.call_soon_threadsafe(
+                self._run_callback,
+                functools.partial(stack_context.wrap(callback), *args, **kwargs))
+        except RuntimeError:
+            # "Event loop is closed". Swallow the exception for
+            # consistency with PollIOLoop (and logical consistency
+            # with the fact that we can't guarantee that an
+            # add_callback that completes without error will
+            # eventually execute).
+            pass
 
     add_callback_from_signal = add_callback
 
diff --git a/tornado/test/ioloop_test.py b/tornado/test/ioloop_test.py
index 616099452..0ca52c66a 100644
--- a/tornado/test/ioloop_test.py
+++ b/tornado/test/ioloop_test.py
@@ -171,10 +171,9 @@ class TestIOLoop(AsyncTestCase):
         other_ioloop.close()
 
     def test_add_callback_while_closing(self):
-        # Issue #635: add_callback() should raise a clean exception
-        # if called while another thread is closing the IOLoop.
-        if IOLoop.configured_class().__name__.endswith('AsyncIOLoop'):
-            raise unittest.SkipTest("AsyncIOMainLoop shutdown not thread safe")
+        # add_callback should not fail if it races with another thread
+        # closing the IOLoop. The callbacks are dropped silently
+        # without executing.
         closing = threading.Event()
 
         def target():
@@ -187,11 +186,7 @@ class TestIOLoop(AsyncTestCase):
         thread.start()
         closing.wait()
         for i in range(1000):
-            try:
-                other_ioloop.add_callback(lambda: None)
-            except RuntimeError as e:
-                self.assertEqual("IOLoop is closing", str(e))
-                break
+            other_ioloop.add_callback(lambda: None)
 
     def test_handle_callback_exception(self):
         # IOLoop.handle_callback_exception can be overridden to catch