Windbg Debugging Misc Tips (Continuously Updating)

 

• Native
• .prefer_dml 1:

a hidden command, enable marking language, showing hyperlinks in some commands, like lm, etc

• .exr -1

show last exception, for both native or managed

• “.symopt+0x40”:force debugger to load unmatched symbol files, like time-stamp mis-match. To disable, –0x40
• .ocommand: execute command from the target trace,

.command “Sa Windbg Cmd:”

then, in the target program, debug output can be written:

Trace.WriteLine(“sa Windbg Cmd: !mk;g;”);

• Managed
• Threads/Callstack/Frame
• !mk

show both managed/native callstack

• !mframe/!mdv

switch to managed frame or show variables for some frame, get frame index from !mk

• Exception/Breakpoints
• debug CLR start-up code:

bu mscorwks!EEStartup “gu;.loadby sos mscorwks”

• !pe

display exception object or most recent exception if no argument

• !soe –derived | –create | –create2 <typeName> [pseudo-register number for results]

e.g, !soe –create System.OutOfMemoryException 1

!soe System.OutOfMemoryException 1; if (@$t1 == 0) {g};

• good sxe sample
• check if it is the expected exception whenever a clr exception thrown:

sxe –c “!soe System.ArgumentNullException 1; .if (@#t1 == 1) {g} .else{.echo “ArgumentNullException hit”}” clr

sxe –c “!soe System.ArgumentNullException 5; !soe System.NotImplementedException 6; .if @@(@#t5 == 0 && @$t6 == 0) {g} .else{‘my exceptions hit’}” clr

"sxe -c "!mk;g" clr"

stop when finding matched trace output(sxe out:Open?Database*)

• Symbols
• !mln

display symbol info for given address

• !mx

display matching symbols

• Heap/Handle Dump/Inspect
• !dumpgen 3

display LOH objects, kind of similar to !dumpheap –min 85000, since LOH also includes quite a few smaller heap blocks.

• !psscor2.gchandleleaks

check potential gchandle leaks, may have false positive info, but generally, if it keeps increasing for each operation, then the operation may cause some handle leaks.

• Object Dump/Analyze
• !gcroot

display references for given object