Apologies that this post is fairly nonsensical. I've put my raw NZ TechEd 2011 notes up here for my reference. I'd like to think that I'll refine them over time, but that probably won't be the case.
WinDBG with the SOS Extension from the .NET framework team can make debugging specific classes of bugs much easier. Such as:
- Memory Leaks
- Deadlocks
- Race conditions
- Dumps form production applications (where it isn't otherwise possible to attach a debugger)
Install from the Windows SDK - Select the Re-distributable Packages "Debugging Tools"WinDBG part of Debugging Tools for Windows Install from the Windows SDK - Select the Re-distributable Packages "Debugging Tools"It's a native "Bare metal" debugger for windows. After one person has installed it others can get it: C:\Program Files\Microsoft SDKs\Windows\v7.1\Redist\Debugging Tools for Windows WinDBG + SOS SOS Extension from the .NET framework team. Attach To Process .loadby sos clr !help !dumpheap -stat : show summary of all objects !dumpheap -type Person : show objects matching type !dumpobj 025.. () : show an individual object !do XXXX .cls : clear screen !dumparray : see array elements !da !threads : .NET threads ~ : all threads ~0s : switch to thread !clrstack : See .NET view of the call stack !eestack -EE : call stack for all threads !pe or !printexception : print exception Object Object Header (4 bytes) MethodTable Pointer Field Data MethodTable EEClass Pointer Method Definitions EEClass Parent Clas Pointer Field Definitions MethodDesc MSIL / x86
Tracking memory leak
Tracking down managed memory leaks (how to find a GC leak)!heapstat : where is the memory all going !dumpheap -stat : find large/numerous objects !dumpheap -mt XYZ : print objects of that type !do mt !gcroot: view garbage collector path to X
Deadlock
!syncblk : who is holding what locks ! ip2md and !dumpil : decompile MethodHeld 1 means it exists but isn't locked
Memory Dump
Write the memory of a process to a file (Need a full dump - all memory in a process to capture heap). procdump.exe - ma deadlock.exe : sysInternals ADPlus Task Manager (need !wow64exts.sw iii created by 64 bit task manager) .dump /ma file > open crash dump MiniDumpWrireDump p/invoke functional for dbghelp.dll
Race conditions
AppDomain.CurrentDomain.UnhandledException
Tips
Dumps are useful for crashes Use MiniDumpWriteDump to capture dumps MS Recommend you create dumps from an external process. A small utility is well worth it Control with a registry or config entry - dumps are large! (250 - 300 mb) Can capture dumps from testers CPU thrashing - take several dumps in quick succession !dumpheap -stat is surprisingly nice for helping to reduce memory consumption lm -v : for troubleshooting "wrong dll" bugs "SOS commands msdn" "msdn bugslayer SOS" Tess Ferrandez
