Analyze the dump file

This commands are the simplest commands to analyze the dump file for .Net,
this commands requires the WinDbg SOS extension from Microsoft, to load the those use
the following command

Failed to load data access DLL, 0x80004005

For .NET 2.0 and above

.loadby sos mscorwks

For .NET 1.1 (the SOS extension has to be downloaded separately)

.load C:\Program Files\Debugging Tools for Windows\clr10\sos.dll

Simple commands

List native threads

~* kb ffff

List clr threads

~* e !clrstack

List clr threads with arguments to the function

~* e !clrstack -p

List all classes located on the CLR heaps order by size of all it object instances

!dumpheap -stat

List all objects in the large object heap

!dumpheap -min 85000

List numer of objects in the finalize queue

!FinalizeQueue

Examine what the finalizer queue does

List all threads

!threads

find the finalizer queue and examine the stack

!clrstack

Advanced commands

Dumps the ASP.NET runtime cache

!dumpaspnetcache -stat

List the size of all objects in the ASP.NET runtime cache

foreach (cachedObject {!dumpaspnetcache -short}) {!objsize ${cachedObject}}

List all objects on the heap

!dumpheap

MT Count TotalSize Class Name
...
6639decc 10000 720000 System.Web.Caching.CacheEntry
790fc6cc 25306 986146448 System.String

List all object of a certain type (here CacheEntry because mt=790fc6cc, from the command above)

!dumpheap -mt 790fc6cc

   Address MT Size
   ...
   3fb319a0 790fc6cc 262168

Dump the specific object (at address 3fb319a0, from the command above)

!dumpobj 3fb319a0

Extract an assembly from the dump

0:000> lm
start end module name
...
05020000 05194000 EPiServer (deferred)

!SaveModule 05020000 c:\temp\TheDumpsEPiServer.DLL

List certain variable from a specific type

Locate the offset address of the variable by dump an object of the certain type.

0:000> !do 1007dc6c
Name: System.Web.Caching.CacheDependency
MethodTable: 66149114
EEClass: 65f86d94
Size: 36(0x24) bytes
(C:\WINDOWS\assembly\GAC_32\System.Web\2.0.0.0__b03f5f7f11d50a3a\System.Web.dll)
Fields:
MT Field Offset Type VT Attr Value Name
793309a0 40013fb 4 System.String 0 instance 1007e08c _uniqueID
...

here is the offset for the variable "_uniqueID" 0x4, use it with the poi function to use as argument for !dumpObj. Here we want to dump a string so we uses the "-nofields" argument to get a more compact output

.foreach (cd { !dumpheap -type System.Web.Caching.CacheDependency -short }) { !do -nofields poi(${cd}+0x4)}

References

Microsoft SOS commands

Version author:
Mattias Lövström

EPiServer version

All