Archive for November, 2018

Crash Dump Analysis Patterns (Part 257)

Tuesday, November 20th, 2018

In addition to Exception Thread analysis pattern (or several threads when we have Multiple Exceptions) that we named Exception Stack Trace there may be a separated thread that reports such exceptions (Exception Reporting Thread):

This dump file has an exception of interest stored in it.
The stored exception information can be accessed via .ecxr.
(4a0c.2ab4): Application hang - code cfffffff (first/second chance not available)

0:002> kc
# Call Site
00 win32u!NtUserCreateWindowEx
01 user32!VerNtUserCreateWindowEx
02 user32!CreateWindowInternal
03 user32!CreateWindowExW
04 CoreMessaging!Microsoft::CoreUI::Dispatch::UserAdapter:: InitializeWindow
05 CoreMessaging!Microsoft::CoreUI::Dispatch::UserAdapter::Initialize
06 CoreMessaging!Microsoft::CoreUI::Dispatch::EventLoop::Callback_Run
07 CoreMessaging!Microsoft::CoreUI::Messaging::MessageSession$R:: Microsoft__CoreUI__IExportMessageSession_Impl::Run
08 CoreMessaging!Microsoft::CoreUI:: IExportMessageSession$X__ExportAdapter::Run
09 CoreMessaging!Windows::System::DispatcherQueue::RunLoop
0a CoreMessaging!Windows::System::DispatcherQueueController:: DispatcherQueueThreadProc
0b kernel32!BaseThreadInitThunk
0c ntdll!RtlUserThreadStart

0:002> ~42kc
# Call Site
00 ntdll!NtWaitForMultipleObjects
01 ntdll!WerpWaitForCrashReporting
02 ntdll!RtlReportExceptionEx
03 eModel!s_ReportAsyncBoundaryHangOnSuspendedThread
04 kernel32!BaseThreadInitThunk
05 ntdll!RtlUserThreadStart

We can spot such a thread in Stack Trace Collection.

Although the example above is for application hang (Blocked Thread) and also illustrates Self-Diagnosis, similar threads may report Handled Exceptions. Usually, Exception Threads are also Exception Reporting Threads as shown in Invalid Parameter analysis pattern example.

- Dmitry Vostokov @ + -

Trace Analysis Patterns (Part 165)

Saturday, November 17th, 2018

Sometimes we put trace statements to track responses to certain environmental actions and conditions but surprised to see them in logs when nothing happened outside that could have triggered them:

We call such an analysis pattern Phantom Activity. This is an indicator that internal program state was not updated correctly. The difference between such activities and Defamiliarizing Effect is that the former messages are expected but not in their current Message Context.

- Dmitry Vostokov @ + -