No. Java is multi threaded, so it uses the same instance of code, but has
900 different "pointers" to the code. Am I correct (besides poorly
explaining)??

-----Original Message-----
From: Walden H. Leverich [mailto:WaldenL@TechSoftInc.com]
Sent: Tuesday, July 30, 2002 2:12 PM
To: 'web400@midrange.com'
Subject: RE: [WEB400] What happened to rpgenerationx.com?


>From: Nathan M. Andelin [mailto:nandelin@RELATIONAL-DATA.COM]
>The engine just synchronizes requests to one Servlet rather than creating
900 separate instances of the same.

Do I understand "synchronize" correctly? Are you saying that if my servlet
takes, say .1 seconds to run, the first person will be .1 second response
time, but if a second person hit at exactly the same time he would get .2
second response time (.1 seconds waiting for the first person to finish then
.1 seconds for the second person to run?)

If 900 users hit at exactly the same time the last one would have a 90
second wait? Granted 900 users won't all hit enter at the same time, but
with a .1 second run time I'd guess 50 users could. That's a 5 second wait
time for the poor 50th user to hit enter.

Please tell me I don't understand your comment.

-Walden

------------
Walden H Leverich III
President
Tech Software
(516) 627-3800 x11
(208) 692-3308 eFax
WaldenL@TechSoftInc.com
http://www.TechSoftInc.com

Quiquid latine dictum sit altum viditur.
(Whatever is said in Latin seems profound.)



-----Original Message-----
From: Nathan M. Andelin [mailto:nandelin@RELATIONAL-DATA.COM]
Sent: Tuesday, July 30, 2002 14:53
To: web400@midrange.com
Subject: Re: [WEB400] What happened to rpgenerationx.com?


> From: "Andrew Borts"
> We actually worked with the IBM folks to try and resolve it, and set
> thread count accordingly to their suggestions - which varied greatly.

In my experience, the thread requirement is roughly 2-3 times the number of
concurrent users.  300 users would need 600-900 available threads, for
example.

Activating that many threads however poses a big problem for the CGI
interface.  Eventually 900 instances of every CGI program become active, and
remain active, if (like Net.Data) they run under a named activation group.

It's like a perpetual memory leak.  Eventually, system resources become
exhausted, and the only solution is to reboot the HTTP Server.

> but the HTTP server isn't as reliable, and darn close
> to sub-par in it's reliability.

Folks need to distinquish between the HTTP Server and the CGI Interface.
While the HTTP Server is both scalable and reliable, CGI has its limits.  It
takes little system resources to support 900 HTTP Server threads.  But 900
BCI (CGI support) Jobs is a whole different matter.

> Is fiddling with the controls of the dang thing the
> option?  Is switching to Apache the option?

The Apache based server uses an equivalent CGI interface, so Apache doesn't
solve the problem.  Just because something works great with five (5) users,
doesn't mean it will work with five hundred.

IBM's answer is a Servlet engine that never instantiates more than one
instance of a Servlet.  The engine just synchronizes requests to one Servlet
rather than creating 900 separate instances of the same.

The same thing can be done with ILE, of course.  But developers need to be
aware of the problem in order to address it.  I addressed the problem with
the design of Relational-Web, which is an ILE framework.

Nathan M. Andelin
www.relational-data.com


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