From: Ben Darnell <ben@bendarnell.com>
Date: Wed, 4 Jan 2012 05:19:51 +0000 (-0800)
Subject: Make fork_processes raise SystemExit instead of returning None when
X-Git-Tag: v2.2.0~49
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4c23ba7e78de99c99b8e1ff1525e8017b0aa75a4;p=thirdparty%2Ftornado.git

Make fork_processes raise SystemExit instead of returning None when
all child processes exit cleanly.
---

diff --git a/tornado/process.py b/tornado/process.py
index 9e19316ad..06f6aa9b0 100644
--- a/tornado/process.py
+++ b/tornado/process.py
@@ -134,6 +134,11 @@ def fork_processes(num_processes, max_restarts=100):
             raise RuntimeError("Too many child restarts, giving up")
         new_id = start_child(id)
         if new_id is not None: return new_id
+    # All child processes exited cleanly, so exit the master process
+    # instead of just returning to right after the call to
+    # fork_processes (which will probably just start up another IOLoop
+    # unless the caller checks the return value).
+    sys.exit(0)
 
 def task_id():
     """Returns the current task id, if any.
diff --git a/tornado/test/process_test.py b/tornado/test/process_test.py
index d1498fa28..91f75b0ab 100644
--- a/tornado/test/process_test.py
+++ b/tornado/test/process_test.py
@@ -50,9 +50,12 @@ class ProcessTest(LogTrapTestCase):
         sockets = bind_sockets(port, "127.0.0.1")
         # ensure that none of these processes live too long
         signal.alarm(5)  # master process
-        id = fork_processes(3, max_restarts=3)
-        if id is None:
-            # back in the master process; everything worked!
+        try:
+            id = fork_processes(3, max_restarts=3)
+        except SystemExit, e:
+            # if we exit cleanly from fork_processes, all the child processes
+            # finished with status 0
+            self.assertEqual(e.code, 0)
             self.assertTrue(task_id() is None)
             for sock in sockets: sock.close()
             signal.alarm(0)
diff --git a/website/sphinx/releases/next.rst b/website/sphinx/releases/next.rst
index b3bcc830c..b2b9db3a2 100644
--- a/website/sphinx/releases/next.rst
+++ b/website/sphinx/releases/next.rst
@@ -4,6 +4,14 @@ What's new in the next release of Tornado
 In progress
 -----------
 
+Backwards-incompatible changes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+* `tornado.process.fork_processes` now raises `SystemExit` if all child
+  processes exit cleanly rather than returning ``None``.  The old behavior
+  was surprising and inconsistent with most of the documented examples
+  of this function (which did not check the return value).
+
 ``IOLoop`` and ``IOStream``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~