From 39cecbc8e932e4977ab952d573ba7aba8a663375 Mon Sep 17 00:00:00 2001
From: Randall Leeds <randall@bleeds.info>
Date: Sun, 13 Mar 2016 16:18:45 -0700
Subject: [PATCH] [arbiter] close sockets on shutdown

Close all the listeners when the arbiter shuts down. By doing so,
workers can close the socket at the beginning of a graceful shut
down thereby informing the operating system that the socket can
be cleaned up. With this change, graceful exits with such workers
will refuse new connections while draining, allowing load balancers
to respond more quickly and avoiding leaving connections dangling
in the listen backlog, unaccepted.

Ref #922
---
 gunicorn/arbiter.py   |  2 ++
 tests/test_arbiter.py | 32 ++++++++++++++++++++++++++++----
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/gunicorn/arbiter.py b/gunicorn/arbiter.py
index 1b55672d..fe96ac00 100644
--- a/gunicorn/arbiter.py
+++ b/gunicorn/arbiter.py
@@ -334,6 +334,8 @@ class Arbiter(object):
         :attr graceful: boolean, If True (the default) workers will be
         killed gracefully  (ie. trying to wait for the current connection)
         """
+        for l in self.LISTENERS:
+            l.close()
         self.LISTENERS = []
         sig = signal.SIGTERM
         if not graceful:
diff --git a/tests/test_arbiter.py b/tests/test_arbiter.py
index ffcf33a5..d6e06dfd 100644
--- a/tests/test_arbiter.py
+++ b/tests/test_arbiter.py
@@ -5,15 +5,18 @@
 
 import os
 
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
+
 import gunicorn.app.base
 import gunicorn.arbiter
 
 
-class PreloadedAppWithEnvSettings(gunicorn.app.base.BaseApplication):
+class DummyApplication(gunicorn.app.base.BaseApplication):
     """
-    Simple application that makes use of the 'preload' feature to
-    start the application before spawning worker processes and sets
-    environmental variable configuration settings.
+    Dummy application that has an default configuration.
     """
 
     def init(self, parser, opts, args):
@@ -22,6 +25,27 @@ class PreloadedAppWithEnvSettings(gunicorn.app.base.BaseApplication):
     def load(self):
         """No-op"""
 
+    def load_config(self):
+        """No-op"""
+
+
+def test_arbiter_shutdown_closes_listeners():
+    arbiter = gunicorn.arbiter.Arbiter(DummyApplication())
+    listener1 = mock.Mock()
+    listener2 = mock.Mock()
+    arbiter.LISTENERS = [listener1, listener2]
+    arbiter.stop()
+    listener1.close.assert_called_with()
+    listener2.close.assert_called_with()
+
+
+class PreloadedAppWithEnvSettings(DummyApplication):
+    """
+    Simple application that makes use of the 'preload' feature to
+    start the application before spawning worker processes and sets
+    environmental variable configuration settings.
+    """
+
     def load_config(self):
         """Set the 'preload_app' and 'raw_env' settings in order to verify their
         interaction below.