COM objects that don’t have the expected lifetime can cause chaos when combined with .NETs garbage collection system.
Category Archives: WinDbg
Getting IUnknown from __ComObject
How do you find the unmanaged COM object that’s being referenced by a .NET object?
Finding the largest free block of address space
I’ve been seeing problems recently with fragmented virtual address space. During the lifetime of a process, bits and pieces of memory are allocated throughout the 2GB 32-bit address space to such an extent that large contiguous blocks of free space are no longer available. If anything subsequently requires a large block of memory (like, for [...]
Also posted in Software Development, Windows Tagged address space, c++, perfmon, private bytes, win32, WinDbg 2 Comments
Diagnosing out of memory errors with VMMap
VMMap is a new tool from Mark Russinovich et al that’s very useful for diagnosing virtual memory/address space exhaustion issues. I describe it here, and give some information that should help you interpret what it reports.
Also posted in Debugging, Software Development, Windows Tagged memory, private bytes, VMMap, win32, WinDbg 1 Comment
WinDbg !locks command broken
It seems that the extremely useful !locks command is broken in 6.11.1.40x, the current and previous release of WinDbg from the debugging tools for Windows.
You’ll get errors like:
0:007> !locks
NTSDEXTS: Unable to resolve ntdll!RTL_CRITICAL_SECTION_DEBUG type
NTSDEXTS: Please check your symbols
The suggested solution seems to be to roll-back to version 6.10.3.233, available from here, or you can just [...]
Troubleshooting an InvalidProgramException
One of the developers who uses the .NET/COM interop DLL that I wrote recently informed me that when they used it in a certain way, they would get a fatal System.InvalidProgramException. Nasty. So I set about seeing how I could find out exactly why this was happening: here are the gory details…
To spoil the ending [...]
Also posted in .NET, Software Development, Windows Tagged .local, .NET, dll, gac, InvalidProgramException, mscoree, mscorjit, mscorwks, WinDbg Leave a comment
Creating a featherweight debugger
What do I mean by “featherweight debugger”? I mean implementing just enough of the debugging framework to get what we need from the debuggee and nothing more.
The problem I was trying to solve was how to get more information from first chance exceptions. We have a great deal of library code that uses catch(…) blocks [...]
Also posted in Debugging, Software Development, Windows 5 Comments
Dumping Excel XLL add-in calls
Using WinDbg it’s possible to get a dump of each XLL call that is made by Excel as it calculates. If you’re using Excel 2003, create the following breakpoint that dumps the symbol at eax+4 (the entry point that is about to be called), then continues.:
bu EXCEL!MdCallBack+0xa880 “dds @eax+0×4 L1; g”
You’ll need to adjust the [...]
Also posted in Debugging, Excel 2 Comments
