ansible: bump UNIX listener default backlog, and set it to match forks.

The connection multiplexer can expect to not be scheduled at least until
every $forks worker processes has attempted a connection, so the backlog
must be able to hold every worker.

ansible_mitogen/process.py

@@ -50,6 +50,7 @@ import mitogen.service
 import mitogen.unix
 import mitogen.utils
 
+import ansible.constants as C
 import ansible_mitogen.logging
 import ansible_mitogen.services
 
@@ -204,6 +205,7 @@ class MuxProcess(object):
         self.listener = mitogen.unix.Listener(
             router=self.router,
             path=self.unix_listener_path,
+            backlog=C.DEFAULT_FORKS,
         )
         self._enable_router_debug()
         self._enable_stack_dumps()

mitogen/unix.py

@@ -63,7 +63,7 @@ def make_socket_path():
 class Listener(mitogen.core.BasicStream):
     keep_alive = True
 
-    def __init__(self, router, path=None, backlog=30):
+    def __init__(self, router, path=None, backlog=100):
         self._router = router
         self.path = path or make_socket_path()
         self._sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)