Re: Why is the iSeries so slow

["Nathan M. Andelin" <nandelin@xxxxxxxxxxxxxxxxxxx>]

> from: "Buck" <buck.calabro@xxxxxxxxxxxx>
> Some customers utterly refuse to put any part of their iSeries
> on the web, and insist on a PC to do their web serving.

This was discussed recently in another thread.  With or without the PC in
the middle, requests are routed from the Internet to the iSeries.  Having a
PC in the middle probably just adds a less reliable, more vulnerable
interface - representing a weak link in the chain.

> Both of these applications are light work on the HTTP/servlet
> engine side.  All of the real work happens on the iSeries.

Are you sure about light servlet workload?  In my experience, servlets
usually consume significant CPU time.  Especially in comparison to ILE
alternatives.  HTTP workload is usually light, however.  The communication
interface between the Java components and the RPG components may be the
bottleneck.

I was just testing one of the samples that came with Webwork (a Java Servlet
framework).  Note the wide variations in time to return the web page.

Request / Milliseconds

1 - 185 ms.
2 - 62 ms.
3 - 6350 ms.
4 - 63 ms.
5 - 62 ms.
6 - 31 ms.
7 - 16 ms.

The servlet is running under Tomcat, hosted on my wife's 2.0 gigahertz
Windows XP box.  I requested the page from my laptop.  Both computers are on
the same LAN, just 10 feet from one another.

What caused the jump from 62 ms to 6350 ms?  I concluded that at that
moment, my wife had just clicked the <save> button on a small Word document.
I think this underscores Windows multitasking capability.

Nathan M. Andelin
www.relational-data.com