Apache crashes under keep-alive test (Apache Users)

Hi,

I am testing Apache HTTPD (2.2.17) with a benchmarking tool called Tsung.

Apache is running the default configuration files, in prefork mode.

The keep-alive is configured as follows:

Timeout 120

KeepAlive On

MaxKeepAliveRequests 200

KeepAliveTimeout 15

The MPM prefork is configured as follows:

StartServers 8

MinSpareServers 5

MaxSpareServers 20

ServerLimit 256

MaxClients 256

MaxRequestsPerChild 10000

</IfModule>

Tsung creates 800 clients, and every client makes 10 requests. Each request has a think time (meaning a waiting time between requests) of 5 seconds.

The problem is that Tsung stops making new requests and Apache says: [error] server reached MaxClients setting, consider raising the MaxClients setting

I tried to increase the ServerLimit and MaxClients directives, but it does not improve the test (or at least the numbers I tried). If I change the test to be done with HTTP 1.0, then the test is done perfectly, without any error. And if I reduce the waiting time between requests the test completes successfully.

There is some explanation to this problem? Lighttpd, Nginx, Cherokee and others work well with this test, without any error.

Thanks for the help.

Regards.

Albert Hidalgo