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markryd/memprofiling.md

Last active August 22, 2016 18:36
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Memory profiling with windbg
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memprofiling.md
  • Start up windbg and attach (F6).
  • Make sure you pick the right version (x86/x64) and run as admin if your app is running as admin.
  • Make sure you have the microsoft symbol servers turned on in Visual Studio -> tools -> options -> debugging -> symbols

Load

.loadby sos clr

Dump the heap

!DumpHeap -stat

Find the biggest type

!DumpHeap -type Foo

Pick an object

!gcroot [address]

Trace the roots to see what is keeping it alive You can use

!dumpobj [address]

To look at the fields of the object if that is helpful. Do this for a few instances so you find old and new ones (Don't forget some are legit). With thanks to @tathamoddie

To look deeper into gcroots, find out which generation your object is in

!GCWhere [address]

Turn on CLR GC notifications

!HandleCLRN

Enable breaking on a GC collection (in this case gen 2) and continue the debugger

!FindRoots –gen 2 
g

Run the app until GC occurs and the debugger breaks then run

!FindRoots [address]
@Hdesai
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Hdesai commented Nov 21, 2014

Prefer Debugger Markup Language After loading sos

.prefer_dml 1

@sheastrickland
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Break on first chance CLR Exception
sxe clr
More handy, break, print exception, show stack
sxe -c "!pe;!clrstack" clr

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