Charles-François Natali <neolo...@free.fr> added the comment:
Here's a patch addressing the multiple bind() problem on Windows.
Note that this problem also affects other parts of the stdlib, which use
SO_REUSEADDR when available.
Also, there's an rather confusing comment in support.find_unused_port():
"""
(This is easy to reproduce on Windows, unfortunately, and can be traced to
the SO_REUSEADDR socket option having different semantics on Windows versus
Unix/Linux. On Unix, you can't have two AF_INET SOCK_STREAM sockets bind,
listen and then accept connections on identical host/ports. An EADDRINUSE
socket.error will be raised at some point (depending on the platform and
the order bind and listen were called on each socket).
However, on Windows, if SO_REUSEADDR is set on the sockets, no EADDRINUSE
will ever be raised when attempting to bind two identical host/ports. When
accept() is called on each socket, the second caller's process will steal
the port from the first caller, leaving them both in an awkwardly wedged
state where they'll no longer respond to any signals or graceful kills, and
must be forcibly killed via OpenProcess()/TerminateProcess().
The solution on Windows is to use the SO_EXCLUSIVEADDRUSE socket option
instead of SO_REUSEADDR, which effectively affords the same semantics as
SO_REUSEADDR on Unix. Given the propensity of Unix developers in the Open
Source world compared to Windows ones, this is a common mistake. A quick
look over OpenSSL's 0.9.8g source shows that they use SO_REUSEADDR when
openssl.exe is called with the 's_server' option, for example. See
http://bugs.python.org/issue2550 for more info. The following site also
has a very thorough description about the implications of both REUSEADDR
and EXCLUSIVEADDRUSE on Windows:
http://msdn2.microsoft.com/en-us/library/ms740621(VS.85).aspx)
"""
I have no idea why it uses SO_REUSEADDR + SO_EXCLUSIVEADDRUSE instead of just
keeping the default setting, since we don't want to allow multiple bind(), but
bypass the TIME-WAIT lingering.
----------
Added file: http://bugs.python.org/file24181/connection_multiple_bind.diff
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<http://bugs.python.org/issue8184>
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