How To identify A hang Process in Linux

[DhsDheeraj]

I am Looking for a script for identifying a hang process in Linux.
I am not sure whether its is on the basis of the %CPU time usage or any other parameters which decides the hang up of a process.

[Steven E. Protter]

Shalom,

A combination of top and or a process analysis script may be needed.

When I suspect a problem like this, I take a look at top and then run ps commands against the suspected process.

Automated identification is not possible in many cases. The eyes and mind of a systems administrator are required.

Take a look at this script for ps command options.

http://www.hpux.ws/?p=8

SEP

[DhsDheeraj]

Thanks for Your comments.But I am not able to get the Script.
Actually I am writing a Monitor program(using java) which should report the status of process if it is hanged up specially a web browser like mozilla.
Can You provide an idea how should i proceed.

[Torsten.]

I think you will easily know if a web browser hangs or not - it won't respond anymore ...

[DhsDheeraj]

Yeah a user can see that but how can i check that using java code.As i need to make a check in the code and then generate a summary for that.
So far What i have thought of taking the CPU usage(High one) and process status(Running) as the parameters to decide that a process has hanged up.But I am not sure of the approach whether its correct or not.
Please correct me if I am wrong.

[Steven Schweda]

First, you're in an HP-UX forum, and there
is a Linux forum:

http://forums.itrc.hp.com/service/forums/familyhome.do?familyId=118

Define "hang process".

A program can get into a state where it uses
no CPU because it's waiting for something to
happen. It's really hung only if that thing
never happens. How can you decide if that
thing _will_ happen?

A program can use all (or nearly all) the CPU
for a long time without producing a result,
because it has much work to do. A user may
believe that it's hung, even though it's
simply working hard.

What condition are you trying to detect?

[DhsDheeraj]

Thanks Steven for providing the link for Linux forum and constructing a refined form of problem definition.
Well I am looking for the first condition.But how can we decide that_thing.
Can You Please tell me your opinion on this by taking care that I am looking for a solution to detect the mozilla web browser in the hang status.

[Steven Schweda]

My opinion (which may be worth little) is
that you would need to know exactly why (or,
at least, approximately why) the program is
hung, that is, what it's waiting for. And
whether there's any chance of it ever getting
the thing it's waiting for. (My personal
psychic powers are weak, and I don't know how
to write a psychic computer program.)

In the case of a Web browser like Mozilla,
the program can send a request (HTTP) to a
server, and wait for a response. It can
_appear_ to hang because of a problem in the
server, but the server could recover at any
time, and all would be well again (unless
Mozilla times out and moves on before the
server responds). It could also have some
problem (internal, or a bad JavaScript or
Java program) which could cause it to wait
for some event which will never happen. I
don't know any practical way you can (from
the outside) distinguish between a
slow-to-respond server and a hung client.

What, exactly, is the problem which you are
trying to solve?

[DhsDheeraj]

Steven ,actually I am doing an assignment where i need to monitor the state of mozilla instance which will be used for connecting to pre-decided Server (for a web based application)
Now in case if the Browser get hang up (i do not know the reasons probably its in any case) then i need to identify it using my java code and report the same(for the time being i need to just log the data).
Can You suggest me an approach for that.

[MSECO_1]

I am not sure for Linux
This is for HP-UX:
ps -ef |grep defunct