Costin,
See below.
> Yes, losing 100 customers per day is worse than losing 10. But you should
> design your server in a way that will have all times less than 9 secs, I
> see no point of running a server if you know that 1% of requests will
take
> 9 secs.
OK. Load levels are unpredictable, so you probably can't rule out a few 9
sec response times in advance. To me, that requires a probability
calculation or earplugs to keep from hearing users scream :-).
<snip>
> Yes, ab measures the time it takes to send a request and receive the
> response.
> If your servlet is doing a database access or something like that you
have
> to add this time - if the Ping servlet takes 2 sec, and a database query
> takes 1 sec you'll probably get about 3 sec per request.
Here's where I need additional clarification. I assume that, in localhost
mode (ignoring TCIP processing time for loopback interface), the time
from sending the request by ab to the receipt of the complete response by
ab occurs in a single thread, so that the elapsed time calculated by ab
would be (using your example) 2 seconds.
If you are saying that database activity isn't fully synchronized with
the servlet, so that the database may be busy doing something after
sending data back to the servlet, I agree. But that affects system cpu
and disk utilization, not start to end servlet processing time. But the
database processing time needed to search, retrieve, and send data to the
servlet would be included in the end-to-end time recorded by ab. Again,
this is based on my reading of the ab code. I hope anybody listening will
set me straight with a procedure/lineno reference to ab if I am mistaken
(which rarely happens :-)).
<snip>
> > > What about using JMeter - it shows you a nice graph of response times (
> > > and if you enable verbose GC you'll notice some patterns :-). (That's why
> > > so much time was spent in 3.x changing the architecture for more reuse.)
> >
> > I've got OptimizeIt to figure out, then I'll look at Jmeter. Can it be
> > used in local host mode like ab?
> Yes, but it's a bit harder to use it with many connections ( it's nice up
> to 20 ). I use to combine it with ab ( i.e. use ab to load the server,
> like 40 concurent connections, and JMeter to display a chart with
> additional 10 connections ).
Thanks for the info. I'll try it.
<snip>
> What's in a bad shape is parameter and cookie handling - but that's not
> shown in a simple request ( but in a simple request with parameters :-).
Thanks for the tips.
> It's "proprietary code", and I don't have it ( one of the previous jobs
).
> But it's very easy to write a small program to do that.
I'll plan to get to that in the future.
> I was thinking to an "ant" task, like the GTest used in tomcat's tests
and
> watchdog. ( few enhancements are needed ). Then you can do your
> "scripts" in xml.
I'll take a look at Gtest. I just started fiddling with ANT today. Like
an idiot I took a full-blown build.xml used to generate a production
system and wondered why I couldn't instantaneously see what was what.
Then [light bulb flashes] I thought, "Why not start simple from scratch?"
As the General Electric Corporation in the US could have said "(Slow)
Progress is our most Important Product". :-)
Roy
--
Roy Wilson
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