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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> |
| Although Apache attempts to increase the limit as required, this |
| may not work if: |
| <ol> |
| <li>Your system does not provide the setrlimit() system call. |
| <li>The setrlimit(RLIMIT_NOFILE) call does not function on your system |
| (such as Solaris 2.3) |
| <li>The number of file descriptors required exceeds the hard limit. |
| <li>Your system imposes other limits on file descriptors, such as a limit |
| on stdio streams only using file descriptors below 256. (Solaris 2) |
| </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>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> |
| </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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