changeset:   72203:fe60689d6a2e
branch:      2.7
user:        Sandro Tosi <sandro.tosi@gmail.com>
date:        Fri Sep 02 20:04:20 2011 +0200
files:       Doc/library/socket.rst
description:
#12781: Mention SO_REUSEADDR flag near socket examples


diff -r f08d4f338b0c -r fe60689d6a2e Doc/library/socket.rst
--- a/Doc/library/socket.rst	Fri Sep 02 17:33:10 2011 +0200
+++ b/Doc/library/socket.rst	Fri Sep 02 20:04:20 2011 +0200
@@ -989,3 +989,22 @@
 
    # disabled promiscuous mode
    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.