Resolve asyncio + multiprocessing problem when testing. (#247)

.gitignore

@@ -1,3 +1,4 @@
+.idea/
 *.egg-info
 *.pyc
 __pycache__

.travis.yml

@@ -34,6 +34,43 @@ jobs:
       dist: xenial
       sudo: required
 
+    - os: osx
+      language: generic
+      python: '3.5'
+      env: TWISTED="twisted==18.7.0"
+      before_install:
+        - eval "$(pyenv init -)"
+        - pyenv install 3.5.5
+        - pyenv global 3.5.5
+      sudo: required
+    - os: osx
+      language: generic
+      python: '3.5'
+      env: TWISTED="twisted"
+      before_install:
+        - eval "$(pyenv init -)"
+        - pyenv install 3.5.5
+        - pyenv global 3.5.5
+      sudo: required
+    - os: osx
+      language: generic
+      python: '3.6'
+      env: TWISTED="twisted==18.7.0"
+      before_install:
+        - eval "$(pyenv init -)"
+        - pyenv install 3.6.5
+        - pyenv global 3.6.5
+      sudo: required
+    - os: osx
+      language: generic
+      python: '3.6'
+      env: TWISTED="twisted"
+      before_install:
+        - eval "$(pyenv init -)"
+        - pyenv install 3.6.5
+        - pyenv global 3.6.5
+      sudo: required
+
     - stage: lint
       install: pip install -U -e .[tests] black pyflakes isort
       script:

daphne/testing.py

@@ -6,11 +6,6 @@
 import traceback
 from concurrent.futures import CancelledError
 
-from twisted.internet import reactor
-
-from .endpoints import build_endpoint_description_strings
-from .server import Server
-
 
 class DaphneTestingInstance:
     """
@@ -121,6 +116,17 @@ def __init__(self, host, application, kwargs=None, setup=None, teardown=None):
         self.errors = multiprocessing.Queue()
 
     def run(self):
+        # OK, now we are in a forked child process, and want to use the reactor.
+        # However, FreeBSD systems like MacOS do not fork the underlying Kqueue,
+        # which asyncio (hence asyncioreactor) is built on.
+        # Therefore, we should uninstall the broken reactor and install a new one.
+        _reinstall_reactor()
+
+        from twisted.internet import reactor
+
+        from .server import Server
+        from .endpoints import build_endpoint_description_strings
+
         try:
             # Create the server class
             endpoints = build_endpoint_description_strings(host=self.host, port=0)
@@ -143,6 +149,8 @@ def run(self):
             self.errors.put((e, traceback.format_exc()))
 
     def resolve_port(self):
+        from twisted.internet import reactor
+
         if self.server.listening_addresses:
             self.port.value = self.server.listening_addresses[0][1]
             self.ready.set()
@@ -249,3 +257,24 @@ def delete_result(cls):
             os.unlink(cls.result_storage)
         except OSError:
             pass
+
+
+def _reinstall_reactor():
+    import sys
+    import asyncio
+
+    from twisted.internet import asyncioreactor
+
+    # Uninstall the reactor.
+    if "twisted.internet.reactor" in sys.modules:
+        del sys.modules["twisted.internet.reactor"]
+
+    # The daphne.server module may have already installed the reactor.
+    # If so, using this module will use uninstalled one, thus we should
+    # reimport this module too.
+    if "daphne.server" in sys.modules:
+        del sys.modules["daphne.server"]
+
+    event_loop = asyncio.new_event_loop()
+    asyncioreactor.install(event_loop)
+    asyncio.set_event_loop(event_loop)