slides for interactive session about debugging .net at TechEd Barcelona 2008

2. 2
Debugging Performance Issues,
Memory Issues and Crashes in
.net Applications
Tess Ferrandez - Norlander
Support Escalation Engineer
Microsoft
Session Code: TLA05-IS

3. 3
Tools and Resources
BuggyBits from http://blogs.msdn.com/Tess
Debugging Tools for Windows
SOS.dll
Process Explorer
Visual Studio Team System Test
TinyGet
Performance Monitor
Our brains

4. 4
Memory Dumps
Mini Dumps
Module Information
Threads Information
Stacks
Full Dumps
Full memory and handle data
Unloaded module information
Thread Time info
adplus –crash –pn <processname.exe>
adplus –hang –pn <processname.exe>

5. 5
SOS.dll
1.1
2.0
For a list of the commands available in sos.dll
run !sos.help
.load clr10sos
.cordll -u –lp <framework dir>
.load <framework dir>sos.dll
or
.loadby sos mscorwks.dll

6. 6
Symbols
Symbols are used to translate an address into a
more understandable function or variable name
WinDbg uses deferred symbol loading
Three types of symbols
Private
Public
Export

7. 7
Symbols (cont.)
Symbols can be stored directly in directories or
on symbol servers
Symbols are not neccesary to translate .NET
function names
.sympath
srv*downstreamstore*http://msdl.microsoft.com/download
/symbols
Or
.symfix downstreamstore

8. 8
Performance issues
Low CPU => waiting for external resources
and/or locks
High CPU => busy server, infinite loops or high
CPU in GC

9. 9
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

10. 10
Crashes
Recycling
Unhandled exceptions
Stack overflow
Fatal Execution Engine Exceptions
Heap Corruption
Out of memory

11. 11
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

12. 12
High memory usage and OOM
Caching and Session State
“Unexpected roots”
Blocked finalizer
DataSet serialization
Large viewstate
Assembly leaks with XmlSerializer
Pinned objects

13. 13
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)

14. 14
Garbage collection
Gen 0
Gen 1
Mark
Sweep
Compact
Gen 2
3
1 2 5 6 7 9
8 10
4 11 12 13 14 15 16

15. 15
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

16. www.microsoft.com/teched
Tech·Talks Tech·Ed Bloggers
Live Simulcasts Virtual Labs
http://microsoft.com/msdn
Developer’s Kit, Licenses, and MORE!
Resources for Developers

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18. 18
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