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From Joe Orton <>
Subject Re: [users@httpd] File descriptor limit in Apache 2.0
Date Tue, 28 Sep 2004 16:48:30 GMT
On Tue, Sep 28, 2004 at 11:28:55AM +0100, James Richardson wrote:
> I have reached a limit on the number of open files, on my SuSE Linux
> Apache 2 server.
> Looking back at the mailing list archives, I see that by editing the
> limits.conf file I can raise the limits above the normal 1024 to some
> fairly arbitrary high value.
> However, I cannot determine from this if I also need to recompile Apache
> with an edited include file for FD_SETSIZE, or whether it will
> automatically work. 

With recent versions of Apache httpd 2.0 on Linux platforms, you do not
need to worry about FD_SETSIZE at all for the core code and bundled
modules, which do not directly use select() any more.

The FD_SETSIZE limit will still be a problem for any third-party modules
or libraries which use select(), notably current releases of PHP have
various nasty issues, and it can also be a problem with mod_ssl/OpenSSL

> I understand that this is a limitation with select(), but am not clear
> that the core apache module actually uses it, and that this _might_ only
> be a problem in some, unspecified other, module.
> I also understand that there may or may not be a problem with the logging
> component of Apache as this may or may not require fds under 1024 to
> operate correctly.

There shouldn't be any problems.

> I would much appreciate it if anybody could shed some light on what I
> might have to do to raise the limits, and end up with a usable system.
> I am currently using, in addition to the normal set.
> Mod_cache
> Mod_disk_cache
> Mod_proxy

These should all be OK.


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