Re: Confused about ASP, "sessions", and queuing of multiple requests

From: Ohaya (Ohaya_at_NO_SPAM.cox.net)
Date: 02/24/04 

Date: Tue, 24 Feb 2004 03:43:22 -0500

Hi All,

I think that I've made some progress, but I'm not quite sure if it's
backwards or forwards :(!

I tried testing with the keepalive (in IIS Manager) for the website
disabled/unchecked. With keepalive on the website disabled, I am seeing
consistently that when I start IE, then go to my test page, ASP is *ALWAYS*
not queuing. I then re-enabled keepalive on the website, and ASP queuing
went back to being inconsistent again.

Disabling keepalive might be ok, but I also found that if I tried to go to
the test page again after the 1st try, ASP would queue the requests :(.

Seems like I can't win :(...

Any other suggestions??

"Ohaya" <Ohaya@NO_SPAM.cox.net> wrote in message
news:uopADcr%23DHA.4060@TK2MSFTNGP10.phx.gbl...
> Ken,
>
> Thanks. I think that I understood that scenario (two IE instances), but
if
> I just run one IE instance and load a HTML page with, say, 2 IMG tags,
e.g.:
>
> <IMG SRC="/test.asp">
> <IMG SRC="/test1.asp">
>
> and I watch Performance Monitor "Requests Executing" and "Requests
Queued",
> I am seeing that sometimes the requests get queued (I can see "Requests
> Queued" increment, then decrement), and sometimes they don't get queued.
I
> haven't been able to discern a pattern to this on my test system at home.
> I've tried things like clearing the IE cache, setting IE to load pages
every
> time, etc., to no avail.
>
> I'm really puzzled about why ASP is queuing requests sometime, and not
> others on my system. If I could figure that out definitively, maybe it'd
> give a hint about why I'm seeing queuing on 2 other systems, but not on
one
> other one :(...
>
> Jim
>
>
>
>
> "Ken Schaefer" <kenREMOVE@THISadOpenStatic.com> wrote in message
> news:OEAjcxp%23DHA.3828@TK2MSFTNGP10.phx.gbl...
> > If you start a new instance of IE, then it does not share any in-memory
> > cookies (include ASP session state cookie) with the first IE instance.
As
> > far as IIS is concerned, this is two separate ASP sessions. That is why
> you
> > are probably seeing parallel processing.
> >
> > Cheers
> > Ken
> >
> > "Ohaya" <Ohaya@NO_SPAM.cox.net> wrote in message
> > news:ezBHIqp%23DHA.3500@tk2msftngp13.phx.gbl...
> > : Sylvain,
> > :
> > : BTW, I forgot to mention:
> > :
> > : If I run my Waitfor test with 2 different instances of IE (on same
> > machine,
> > : but 2nd IE started from Start, not using Ctrl-N) simultaneously, I see
> > : Requests Executing in Perfmon as 2, i.e., in this situation, IIS *IS*
> > : apparently processing both requests simultaneously/in parallel.
> > :
> > : Like I said, I'm confused about what is different (specifically)
between
> > the
> > : above test, and generating multiple HTTP requests from a single IE
> > : instance...
> > :
> > :
> > :
> > : "Ohaya" <Ohaya@NO_SPAM.cox.net> wrote in message
> > : news:OiJzRkp%23DHA.2520@TK2MSFTNGP11.phx.gbl...
> > : > Sylvain,
> > : >
> > : > Thanks for responding...
> > : >
> > : > Re. Waitfor, I just installed it for the test I described.
> > : >
> > : > Sorry if I'm being obtuse. I think I understand that one IE
instance
> > can
> > : > generate multiple HTTP requests into IIS, e.g., in the instances
that
> > you
> > : > described. In our case, I think your example of setting an IMG SRC
to
> > an
> > : > ASP is exactly what we have, with multiple of these IMGs on one
page.
> > : >
> > : > But, I guess I'm still unclear about when IIS/ASP will or will not
> > handle
> > : > these multiple requests in a "queuing" fashion vs. not in a queuing
> > : fashion.
> > : >
> > : > What exactly determines this? As I mentioned, the posts I've seen
> > vaguely
> > : > mention "in the same session", without clearly defining what they
mean
> > by
> > : a
> > : > "session".
> > : >
> > : > Actually, the reason that I'm chasing all of this around is that we
> are
> > : > running IIS on a multiprocessor server. With the IE client firing
> > : multiple
> > : > requests to IIS, we thought that the multiple requests from IE would
> be
> > : > spread across the multiple processors.
> > : >
> > : > But on our production server, instead, for a given user operation at
> the
> > : > IE/client end, which, again, creates several HTTP requests to IIS,
> we're
> > : > seeing CPU activity on 1 CPU, then the next CPU, then the next CPU,
> > etc.,
> > : > until the user operation is complete.
> > : >
> > : > The conclusion we're coming to is that for some reason ASP on the
> > : production
> > : > server is not handling the multiple requests "in parallel", but
rather
> > : > queuing the requests (we see the parallel processing on a different
> > : > multiprocessor server that we use for testing, but not on the
> production
> > : > machine).
> > : >
> > : > We just cannot figure out what is different between these 2 machines
> > that
> > : > would cause queuing the requests in one case, but not in the other.
> > : >
> > : > Thanks,
> > : > Jim
> > : >
> > : > "Sylvain Lafontaine" <sylvain aei ca (fill the blanks, no spam
> please)>
> > : > wrote in message news:O7nX9Np%23DHA.688@tk2msftngp13.phx.gbl...
> > : > > That's true since IIS 3.0 and there are occasions when you don't
> need
> > to
> > : > > make quick refresh to see it in action.
> > : > >
> > : > > For example, this is necessary when the IE is making simultaneous
> > : requests
> > : > > to the IIS. Exemple of this are when you are dividing your page
> using
> > : > > Frameset: each frame contains one HTML page as its source.
> Refreshing
> > a
> > : > > frameset then require to ask the server for more than one HTML
page.
> > : > >
> > : > > Another example is when the source of an objet is an ASP page,
like
> > : this:
> > : > >
> > : > > <img src="get_the_image.asp">
> > : > >
> > : > > The use of Javascript and of other advanced facilities for
> requesting
> > : data
> > : > > from one or more ASP pages also rise the possibilities of having
> > : multiple
> > : > > simultaneous requests to the web server. It is clear from those
> > example
> > : > > that the server cannot run these requests in parallele because of
> the
> > : > > possibility that the codes inside theses pages can make
> contradictory
> > : > > changes to Session variables, global variables and/or other
objects,
> > : like
> > : > > backend requests to a SQL-Server. This should clear any confusion
> > into
> > : > your
> > : > > mind.
> > : > >
> > : > > By the way, using things like WaitFor and others objets for timing
> in
> > : ASP
> > : > > can result in a severe degradation of performance from the IIS and
> > their
> > : > > usages must be reserved to the cases when they are strictly
> necessary.
> > : > >
> > : > > S. L.
> > : > >
> > : > > "Ohaya" <Ohaya@NO_SPAM.cox.net> wrote in message
> > : > > news:u0nrjZo%23DHA.552@TK2MSFTNGP11.phx.gbl...
> > : > > > Hi,
> > : > > >
> > : > > > I'm trying to understand a situation where ASP seems to be
> > "blocking"
> > : of
> > : > > > "queuing" requests. This is on a Win2K Advanced Server, with
> IIS5.
> > : > > >
> > : > > > I've seen some posts (e.g.,
> > : > > >
> > : > >
> > : >
> > :
> >
>
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=Tidy7IDbDHA.2108%40cpmsftngxa06.phx.gbl)
> > : > > > that indicate that ASP will queue up requests when they come in
> with
> > : the
> > : > > > same "session".
> > : > > >
> > : > > > My first question is "Can someone confirm that this is true?"
(see
> > : > below).
> > : > > >
> > : > > > My second is regarding what "same session" means in this
context?
> > : > > >
> > : > > > Several of the posts that I've seen with respect to this queuing
> > just
> > : > say
> > : > > > "session", but I've also seen some posts that say "ASP session",
> and
> > : > which
> > : > > > specifically mention "the ASP Session object". This latter
> > reference
> > : > > ("ASP
> > : > > > Session object") is more precise, but my testing (again, see
> below)
> > : > seems
> > : > > to
> > : > > > indicate that this interpretation of "session" is not "ASP
Session
> > : > > object".
> > : > > >
> > : > > > Here's the test that tried:
> > : > > >
> > : > > > 1) I installed the Waitfor from ServerObjects
> > : > > > (http://www.serverobjects.com/products.htm), and created a small
> > : > > "text.txt"
> > : > > > file in c:\.
> > : > > >
> > : > > > 2) I put Waitfor.asp in my website.
> > : > > >
> > : > > > 3) I ran Performance Monitor and added the "Requests Queued"
> counter
> > : > > >
> > : > > > 4) Using IE, I went to http://myserver/waitfor.asp
> > : > > >
> > : > > > 5) Once it connected, I started clicking the IE Refresh button
> > : > > >
> > : > > >
> > : > > > As I clicked the IE Refresh button, I could see the "Requests
> > Queued"
> > : > > > counter climb in Performance Monitor.
> > : > > >
> > : > > > The above test SEEM to at least indicate that ASP will *INDEED*
> only
> > : > > process
> > : > > > a single request from IE, i.e., that ASP *IS* queuing, but I'm
> still
> > : > > > confused about under what circumstances this queuing will happen
> > (what
> > : > > does
> > : > > > "session" mean in this context?).
> > : > > >
> > : > > > Can someone clarify this?
> > : > > >
> > : > > > Thanks, and apologies for both the cross-post and somewhat long
> > : post...
> > : > > >
> > : > > >
> > : > >
> > : > >
> > : >
> > : >
> > :
> > :
> >
> >
>
>