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| <h1 align="CENTER">File Descriptor Limits</h1> |
| |
| <p>When using a large number of Virtual Hosts, Apache may run |
| out of available file descriptors (sometimes called <cite>file |
| handles</cite> if each Virtual Host specifies different log |
| files. The total number of file descriptors used by Apache is |
| one for each distinct error log file, one for every other log |
| file directive, plus 10-20 for internal use. Unix operating |
| systems limit the number of file descriptors that may be used |
| by a process; the limit is typically 64, and may usually be |
| increased up to a large hard-limit.</p> |
| |
| <p>Although Apache attempts to increase the limit as required, |
| this may not work if:</p> |
| |
| <ol> |
| <li>Your system does not provide the setrlimit() system |
| call.</li> |
| |
| <li>The setrlimit(RLIMIT_NOFILE) call does not function on |
| your system (such as Solaris 2.3)</li> |
| |
| <li>The number of file descriptors required exceeds the hard |
| limit.</li> |
| |
| <li>Your system imposes other limits on file descriptors, |
| such as a limit on stdio streams only using file descriptors |
| below 256. (Solaris 2)</li> |
| </ol> |
| In the event of problems you can: |
| |
| <ul> |
| <li>Reduce the number of log files; don't specify log files |
| in the VirtualHost sections, but only log to the main log |
| files.</li> |
| |
| <li> |
| If you system falls into 1 or 2 (above), then increase the |
| file descriptor limit before starting Apache, using a |
| script like |
| |
| <blockquote> |
| <code>#!/bin/sh<br /> |
| ulimit -S -n 100<br /> |
| exec httpd</code> |
| </blockquote> |
| </li> |
| </ul> |
| |
| <p>Please see the <a |
| href="../misc/descriptors.html">Descriptors and Apache</a> |
| document containing further details about file descriptor |
| problems and how they can be solved on your operating |
| system.</p> |
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