asp/iis hanging and failing without error message!

[frank]

Hi all,

I have a largish asp-driven site that's crashing intermittently in a way
that's just causing me to scratch my head a lot. I've not seen this happen in
about five years of developing asp apps. This is what happens:
asp v3
access 2000 database
win 2003 server.

1. It runs on my server and on my test server just fine. Complete test of
every page completes fine.
2. On the production server, it just fails a few times a day. When I say
fails, you don't get any error message, but it just doesn't serve pages. It
sits there and w3wp.exe consumes slowly more memory (About 50k a second), not
returning any pages.
The user experiences a page that is requested, but nothing comes back,
doesn't even timeout.
3. recycling the worker process or restarting IIS clears the problem and it
runs again.
4. It's definitely asp-related becuase when the box is locked up, it still
returns .htm pages and you can still login using remote desktop.
5. I'm pretty good at closing and disposing of objects.
6. We moved the production server to a different box and it made no
difference, still these intermittent freezes.
7. This is the only site on the box.
8. Don't think its an 'infinite loop' problem (where I omitted rs.movenext).
I've been logged into the box by remote access a couple of times when it's
been reported to me by the client and there hasn't been anything like the
100% cpu utilisation I've seen with that problem 1-2% at most.


Questions:
a) Has anyone seen this before? Does anyone know what could be causing it?
b) could using an inappropriate locktype in db connection strings cause this
problem? If not, could connections (But not recordsets) left open cause this
error?
c) is there any way I can get IIS or any other tool to record exactly what
is causing this lurch, or, failing that, record response times for page
requests. Basically, any profiling tips would be really good. I have remote
desktop access to the machine.

Any help greatly appreciated. I'm tearing chunks of hair out here and the
client is livid.

Cheers,


frank

 

[Bob Barrows [MVP]]

Hi all,

I have a largish asp-driven site that's crashing intermittently in a
way that's just causing me to scratch my head a lot. I've not seen

Questions:
a) Has anyone seen this before? Does anyone know what could be
causing it? b) could using an inappropriate locktype in db connection
strings cause this problem? If not, could connections (But not
recordsets) left open cause this error?

You aren't closing and destroying your connections on each page? Why not?
You are preventing connection pooling from working by doing this.

c) is there any way I can get IIS or any other tool to record exactly
what is causing this lurch, or, failing that, record response times
for page requests. Basically, any profiling tips would be really
good. I have remote desktop access to the machine.

You don't mention whether you've checked the Event log on the machine.

Are you using On Error Resume Next to mask any errors that occur?

IIS logs all requests so you should check the IIS logs.

Bob Barrows

 

[Tom Kaminski [MVP]]

IIS logs all requests so you should check the IIS logs.

Just look for the last ASP to execute ...

 

[frank]

Hi guys,

thanks for the suggestions.
Nope: not using on error resume next for just that reason: it masks errors
and makes debugging a nightmare.

I'm pretty sure it's not a coding error as such - checking the logs hasn't
helped me so far. At one point I was able to make the box lurch pretty much
at will by throwing it a complex search query that would return a few
thousand row and perform a reg-ex pattern match on each field. The script
took a few seconds to run, and when it returned to zero the box was locked
up, but again, it doesn't happen every time I run the script. I did this
whilst logged into the server using remote access and cpu useage went up to
100% for a few seconds, then back down. When it's locked-up, it still serves
html pages, just not asp. Actually, next time it dies I'm going to see if it
still serves asp pages that don't contain database hits. When I ran the same
script on my test server, it performed fine, but I can't simulate multiple
users on my test box.

Any ideas?

Cheers,

FRank

 

[s_m_b]

what sort of script timeout have you got? I've come across this kind of
issue once or twice, and forcing the script to stop after a matter of
seconds has helped by allowing me to track down where the hang happens.