From 172f374a63bfc61f71ee925463927a81350b66da Mon Sep 17 00:00:00 2001
From: Sandro Tosi <sandro.tosi@gmail.com>
Date: Fri, 2 Sep 2011 20:06:31 +0200
Subject: #12781: Mention SO_REUSEADDR flag near socket examples
---
Doc/library/socket.rst | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/Doc/library/socket.rst b/Doc/library/socket.rst
index d462bb7..64b4183 100644
--- a/Doc/library/socket.rst
+++ b/Doc/library/socket.rst
@@ -1014,6 +1014,25 @@ the interface::
s.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF)
+Running an example several times with too small delay between executions, could
+lead to this error::
+
+ socket.error: [Errno 98] Address already in use
+
+This is because the previous execution has left the socket in a ``TIME_WAIT``
+state, and can't be immediately reused.
+
+There is a :mod:`socket` flag to set, in order to prevent this,
+:data:`socket.SO_REUSEADDR`::
+
+ s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+ s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+ s.bind((HOST, PORT))
+
+the :data:`SO_REUSEADDR` flag tells the kernel to reuse a local socket in
+``TIME_WAIT`` state, without waiting for its natural timeout to expire.
+
+
.. seealso::
For an introduction to socket programming (in C), see the following papers:
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