Support gRPC Python client-side fork with epoll1

A process may fork after invoking grpc_init() and use gRPC in the child
if and only if the child process first destroys all gRPC resources
inherited from the parent process and invokes grpc_shutdown().
Subsequent to this, the child will be able to re-initialize and use
gRPC. After fork, the parent process will be able to continue to use
existing gRPC resources such as channels and calls without interference
from the child process.

To facilitate gRPC Python applications meeting the above constraints,
gRPC Python will automatically destroy and shutdown all gRPC Core
resources in the child's post-fork handler, including cancelling
in-flight calls (see detailed design below). From the client's
perspective, the child process is now free to create new channels and
use gRPC.

1 files changed, 25 insertions, 0 deletions

diff --git a/src/python/grpcio_tests/commands.py b/src/python/grpcio_tests/commands.py
index a23c980017..0dfbf3180b 100644
--- a/src/python/grpcio_tests/commands.py
+++ b/src/python/grpcio_tests/commands.py
@@ -202,3 +202,28 @@ class RunInterop(test.test):
         from tests.interop import client
         sys.argv[1:] = self.args.split()
         client.test_interoperability()
+
+
+class RunFork(test.test):
+
+    description = 'run fork test client'
+    user_options = [('args=', 'a', 'pass-thru arguments for the client')]
+
+    def initialize_options(self):
+        self.args = ''
+
+    def finalize_options(self):
+        # distutils requires this override.
+        pass
+
+    def run(self):
+        if self.distribution.install_requires:
+            self.distribution.fetch_build_eggs(
+                self.distribution.install_requires)
+        if self.distribution.tests_require:
+            self.distribution.fetch_build_eggs(self.distribution.tests_require)
+        # We import here to ensure that our setuptools parent has had a chance to
+        # edit the Python system path.
+        from tests.fork import client
+        sys.argv[1:] = self.args.split()
+        client.test_fork()