Re: Overwhelming a Web Application Server

["Walden H. Leverich" <WaldenL@xxxxxxxxxxxxxxx>]

> Perhaps based on limited knowledge, it seems to me that Web servers 
> and Application servers are not very well equipped to manage complex 
> and intense workloads.  

I disagree completely, app and web servers can deal with immensely
complex and intense workloads, just look at large web sites (amazon,
microsoft, facebook, twitter, etc.) But complex loads are exactly that,
complex. 

> A stress test tool may sound simple, but does it really pinpoint 
> bottlenecks? And what if the problem is not a bottleneck, but 
> resource contention, instead?

A stress tool will do nothing but stress the system. You need system
monitoring inplace to tell you where the bottlenecks are. As for
bottleneck vs. resource contention, the difference is? In either case it
will cause a slowdown. Sure, a 56K line may be a "bottleneck" where a
lock-wait on a records in a table may be a "resource contention" but
both cause scaling issues. The only way you'll find these is to measure
the system under stress. Now, stress can be from a testing tool or
stress can be from your production users, but it's stress either way,
and I'd prefer it be from a tool in test. :-)

> "The problem is seldom where you think it is."

I can't count the number of times I was _sure_ I knew where the problem
was, only to find it was somewhere else when we actually measured. Also,
there is only ever one bottleneck in the system at a time. There's a
single choke-point. Remove it, and you'll find the next, but there's
only one.

-Walden