| Solved: Re: VDS with Debian 5 performs much worse than with Debian 3. [message #38939 is a reply to message #38711] |
Sun, 21 February 2010 18:01   |
tryl
Messages: 4
Registered: January 2010
Location: Denmark
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Junior Member |
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I found the problem and the solution:
I the PHP scripts with the most hits I used gethostbyaddr() to get the host name of the web client. It is an advanced web counter, so I have to do this.
The problem doing it with that function is that it is relatively heavy on the system, but that had not been a problem on several PHP 4 installations over several years.
With PHP 5 that changed. Usually there were no problems, but some times a DNS request would take a long time or just hang. Maybe that hanging request blocked for others or maybe Apache had to launch more processes and maybe it hit the ceiling so it could not create more.
It probably only hit 1 of 100 requests, but with the amount of traffic I have, that quickly built up within minutes.
Solution?
<?php
$ip = long2ip(ip2long($this->ipAddr)*1);
$ip = escapeshellarg($ip);
$out = shell_exec("host --quick --timeout=2 $ip");
// Parse the host name.
$out = split("\n", $out);
if (count($out) >= 2) {
$out = split(" ", $out[0]);
if (count($out) >= 2) {
$name = $out[1];
}
}
?>
where the IP address is in $this->ipAddr and the host name ends up in $name if it can be set. The script runs a process calling the version of the host command that exists on my system. Other systems may have other versions which would require the parse block to be different.
The implementation is a little paranoid: I convert the IP address to a number, multiply by 1 (so it will always be a integer) and converts it back again. Even with that, I do what you always must: Escape anything from the user which goes into a a shell, file name, SQL etc.
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