testing server capacity

thanks. One more question. Does ab benchmark my website in general, or just the server? What I am trying to say is that my landing page does 100 queries in 2-5 secs (according to django-debug-toolbar). But, can it really handle 1000 requests in bunches of 10? Even if Apache manages to handle all those requests, MySQL may refuse. Does ab show that? Or will I need another tool (like Load Impact)?

PS: And why I get a 'Document Length' of 0 bytes? (with ab)

ab benchmarks whatever site you tell it to. For example, if you run this:

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ab -n 1000 -c 10 http://mydomain.com/

... then it will hit http://mydomain.com/ 1000 times, 10 requests at a time.

ab has the option to include response codes in the output, so if MySQL falls down and causes your site to return a 500 response, then it should be able to show you that.

Regarding the document length, ab is reporting whatever your site is responding with. I don't know anything about your site, so I'm not in a position to know why it would return a 0-byte response. :)