Blocked LPC thread, coupled processes, stack trace collection and blocked GUI thread: pattern cooperation
CARE: Crash Analysis Report Environment
DATA (Dump Analysis + Trace Analysis) Facebook group
Please join the community of memory (dump) and trace analysis engineers. This group promotes scientific methods and memory dump-based worldview.
Twitter @ DumpAnalysis You can now follow portal and blog news at DumpAnalysis on Twitter
LinkedIn Group Dr. Watson Enthusiasts All about Dr. Watson errors and more. Get news, excerpts and progress reports about the forthcoming book The Science of Dr. Watson: An Illustrated History of Debugging (ISBN 978-1906717070)
2010 (0x7DA) - The Year of Dump Analysis 2011 (0x7DB) - 2020 (0x7E4) The Debugging Decade
This small case study continues where Not using checklists common mistake case study left, after identifying the blocked LPC thread in ServiceA process. We know that ServiceA always asks (coupled with) ServiceB and, indeed, when looking at the latter stack trace collection we see a GUI thread showing a dialog box:
0:000> ~13kc
ntdll!KiFastSystemCallRet
USER32!NtUserWaitMessage
USER32!InternalDialogBox
USER32!DialogBoxIndirectParamAorW
USER32!DialogBoxIndirectParamW
comdlg32!NewGetFileName
comdlg32!NewGetSaveFileName
comdlg32!GetFileName
comdlg32!GetSaveFileNameW
WARNING: Stack unwind information not available. Following frames may be wrong.
DllA!DllEntryPoint
ServiceB!Initialize
[…]
ServiceB!ServiceThread
kernel32!BaseThreadStart
From function names we can infer that the thread was displaying a “Save File As” common dialog box but the service was not allowed to interact with a desktop. This made the service blocked and, in return, made ServiceA blocked too. The suggestion was to enable ServiceB to interact with the desktop and keep an eye on DllA.
- Dmitry Vostokov @ DumpAnalysis.org -
_1125.png)
Coming Soon:
Debugging Notebook: Essential Concepts, WinDbg Commands and Tools
Crash Dump Analysis for System Administrators and Support Engineers
New Magazines:
Debugged! MZ/PE: MagaZine for/from Practicing Engineers
New Books:
Memory Dump Analysis Anthology, Volume 3
First Fault Software Problem Solving: A Guide for Engineers, Managers and Users
x64 Windows Debugging: Practical Foundations
Also available:
Windows Debugging: Practical Foundations
DLL List Landscape: The Art from Computer Memory Space
Dumps, Bugs and Debugging Forensics: The Adventures of Dr. Debugalov
WinDbg: A Reference Poster and Learning Cards
Memory Dump Analysis Anthology, Volume 2
Memory Dump Analysis Anthology, Volume 1
New Children's Book:
