When you do a system call you actually do a fork() followed by an exec(). From the docs for system(): 

Does exactly the same thing as ``exec LIST'' except that a fork is don
+e first, and the parent process waits for the child process to comple
+te.

[download]

The OS requires a reasonable amount of time to fire up a new process (thus mod perl is faster than vanilla perl as you avoid this overhead) - sure less than a second but often in the order of hundreds of miliseconds.

With your fork/system call example you have 2 forks (with the time overhead) per hit on the web-server. With the basic LWP method you have only one fork so in rough terms you should get double the kids hitting the server given that forking is a bottle neck, not loading/running code or memory.

As a variation on the hammer theme described above just make the kids hit the server more than once. If each child hit the server say 50 times you will get a steadily increasing load (as more kids fork off); a sustained peak load (all kids hitting the server); and then a taper as the kids die off. This will give you a very sustained peak load. Don't blame me if your server cries - it is IIS ;-)

<DISCLAIMER>Quite seriously this sort of code can bring you system to its knees so use with due care. It will in all liklihood saturate the network thus performing a DNS attack on yourself. Perhaps best run after hours.</DISCLAIMER> 

#!/usr/bin/perl -w

package Brutal::Web::Server::Test;

use strict;
use LWP::Simple;

my $kids  = 100;
my $hits_per_kid = 50;
my $output;

while ($kids) {
    my $pid = fork;
    # Parent
    if ($pid) { 
      $kids--; 
    }
    elsif ($pid == 0) {
        do {$output = get('http://www.mysitegoeshere.org') }  for 1 ..
+ $hits_per_kid;
      exit;
    }
    else {
        die "Fork failed $!\n";
    }
}

[download]

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

In reply to Re: Re: Re: Stress testing a web server by tachyon
in thread Stress testing a web server by ibanix

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