Building Pen on Linux for lots of connections

From: Ulric Eriksson (
Date: Fri Jun 25 2004 - 01:09:39 CEST

To use Pen with a very large number of simultaneous connections, the
preprocessing macro FD_SETSIZE must be increased. The default value varies
between operating systems, as does the maximum supported. Pen will try to
catch attempts to run out of spec.

The select() used by Linux is broken in this respect, and doesn't
allow FD_SETSIZE to be changed from the default. The solution is
to not use Linux, or to change the #defines in the relevant include
files: <linux/posix_types.h> and <bits/typesizes.h>. Look for lines
like this:

#define __FD_SETSIZE 1024

and change them to what you really want, such as:

#define __FD_SETSIZE 16384

You probably want to change them back afterwards.

The above information has been added to the INSTALL in Pen 0.14.0, since
it is a rather frequently asked question.


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