RE: What does Timeout in the httpd.conf file accomplish? (Apache Users)

the script is a silly trivial example of how a more complex script with a loop that is not obvious could cause a major issue.
the scripts ran indefinitely despite the timeout. the server had to manually restarted.

From: Jeroen Geilman [jeroen@xxxxxxxxx]

Sent: Sunday, June 19, 2011 8:46 PM
To: users@xxxxxxxxxxxxxxxx
Subject: Re: What does Timeout in the httpd.conf file accomplish?

On 06/20/2011 02:38 AM, Zaccone, Warren wrote:

Running multiple copies of this script concurrently brings httpd into a hang state, that it will not recover from without manually restarting the httpd server.

ab -n 300 -c 300 http://myserver/mysite/loop.php

You're requesting a single URL 300 times concurrently.
This means that apache has to dedicate 300 threads at once to this purpose.

this is a trivial test case.

If you're not running worker, and your minspare is lower than 250 or so, it's going to take MINUTES to even get to number 300.

As documented, when many new (prefork) threads are being requested at once, apache will only spawn one per second, to protect itself from attacks and runaway processes.

the point is not how the situation was produced, but rather why aren't the 256 workers that are running this script stoppe. I know that I started more than 300.

<?php

/* loop.php */

while (1) sleep (20);

?>

And the request does nothing for 20 seconds before returning.

What exactly are you testing here ?

reproducing fact. that a single user of my server can bring down the server with a simple script. running it from the unix command prompt is not realistic, but it is realistic that an automated script from another server could be doing so.

I have timeout set to 900 but it does not appear to be working. What does timeout in the httpd.conf do?

As documented, Timeout determines the maximum number of seconds that a single request may take.

I am afraid not - each of the copies of httpd running the above script ran indefinitely.

Will the httpd.conf timeout protect the server from such scripts or is there something else.

Yes, Timeout works on the HTTP level, so everything sent over HTTP is affected by it.

This means everything.

I am configured using Prefork

Then that apachebench run you show above is bloody stupid.

please Explain?

settings are:

Timeout 900

MaxKeepAliveRequests 100

StartServers        5

MinSpareServers     5

MaxSpareServers     10

MaxClients          256

You can't even SERVE 300 concurrent requests.

MaxRequestsPerChild 0

Ok, so you have given me some useful advice here, unintentionally. this value should not be 0?

If you run PHP, this kills apache.
Eventually.

# pstack 22040 (root)

You have no idea what you are doing.

This was entirely unnecessary. Why do you say this. I am reproducing an ellusive situation with a trival test case.., there is no reason to get personal. I thought this forum was a place people could ask silly questions and not be attacked.

-- 
J.