What diagnostic approaches to take to debug .NET production application

The app. sporadically hangs sometimes, shoots up in memory and sometimes just 开发者_运维百科dies out. This behavior might not be available in dev. environment.

What all approaches can one take to find the problem areas ? In case of web app and what in case of thick WPF app.

I am interested to know of approaches, i do not currently have details of some particular scenario.

EDIT

Ok I am sorry the question is broad, but i think that was my intention.

I want to know of best practices/approaches. (Links/Pointers may be). What the .net people here tend to use.

What situations trouble the most. Like is it deadlocks or memory leaks or something else to be aware of while writing .net apps.

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The first-of-everything which is a must for every debugging scenario:

Get your issue reproducible!

Said that, there are different approaches how to to accomplish this, depending much on what kind of application you have. For example, if you have a user sitting on front of your program to which you can talk directly, and you have read-access to the production data, it might be sufficient to make a copy of the data and let the user mail you a short report what he/she did to get to the crash scenario.

On the other hand, if you have thousands of users you using your web app over the internet, you will need additional tools like logging, instrumentation and/or a crash dump.

Read these former SO posts

.NET Production Debugging

.net debugging on production server

to get some more info.