Debugging .net issues - Presentation for TechEd EMEA 2008

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Common ASP.NET production
issues and how to troubleshoot
them with WinDbg
Tess Ferrandez - Norlander
Support Escalation Engineer
Microsoft
Session Code: WUX405

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We will be using
BuggyBits from http://blogs.msdn.com/Tess
Debugging Tools for Windows
SOS.dll
Task Manager
Visual Studio Team System Test
TinyGet
Performance Monitor
Our brains

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Performance issues
Low CPU => waiting for external resources
and/or locks
High CPU => busy server, infinite loops or high
CPU in GC

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Performance issues

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Performance issues
High or Low CPU?
Get memory dump(s)
Look at threads
VSTS Test and Profiling is good if you can repro
in a test environment

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Crashes
Recycling
Unhandled exceptions
Stack overflow
Fatal Execution Engine Exceptions
Heap Corruption
Out of memory

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Crashes and Exceptions

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Crashes and Exceptions
Check out the eventviewer
Disable recycling options
Get memory dump(s)
Look at faulting stacks or logs if neccesary
Use TrackClr.cfg to track exceptions during
testing

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High memory usage and OOM
Caching and Session State
“Unexpected roots”
Blocked finalizer
DataSet serialization
Large viewstate
Assembly leaks with XmlSerializer
Pinned objects

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Memory

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High memory usage and OOM
What are you leaking? (native, .net, assemblies)
Take multiple dumps when memory is raising
and compare
Check the finalizer
Check the Large object heap
Try to group “leaking” objects
Figure out why they are sticking around
(rooted)

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Remember...
There are tools out there to track down these
types of issues
http://blogs.msdn.com/Tess
Track exceptions during testing with
TrackCLR.cfg
Debugging Tools for Windows

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21. Related Content
http://blogs.msdn.com/johan
http://blogs.msdn.com/carloc
http://blogs.msdn.com/dougste
http://blogs.msdn,.com/tom

22. TLA05-IS Debugging Performance Issues, Memory Issues and Crashes in .net
Applications
Track Resources

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