Software Diagnostics Library

Got this book yesterday in the post and started reading. Table of contents is amazing for its practical depth and breadth. If you want me to provide a review in a language of concurrency  (I’m reading many books in parallel) I would simply say one word:

Priority!

It simply means priority reading for any Windows software developer and maintainer. Invaluable for any engineer debugging complex software problems and analyzing Windows crash dumps. Simply because Microsoft OS and CLR developers use all this concurrent stuff and best practices described in the book so it is vital to be able recognize them in memory dumps. After reading this book you also get priority boost in your understanding of process and thread dynamics and your ability to plan, architect, design and implement concurrent applications and services.

Concurrent Programming on Windows (Microsoft .NET Development Series)

- Dmitry Vostokov @ DumpAnalysis.org -

Previously announced my old Resume and CV as a book was submitted to print and distribution worldwide this morning.

It features UML statechart diagrams on the following front cover I designed myself:

- Dmitry Vostokov @ DumpAnalysis.org -

“The” computer “is the only place where” a crash “comes before” hang.

Anonymous American Saying

- Dmitry Vostokov @ DumpAnalysis.org -

“… the” debugger “(my almighty” application ”) …”

Thomas Jefferson, TO JAMES MONROE, Paris Mar. 18. 1785

- Dmitry Vostokov @ DumpAnalysis.org -

A book can serve the role of CV but this weekend another idea got into my mind is to publish my old pre-Citrix times CV (1987 - 2003) as a book and as an example of a guy with CV-writing obsession like I had 5 - 8 years ago:

• Title: Resume and CV: As a Book
• Paperback: 16 pages
• Publisher: Opentask (01 Dec 2008)
• ISBN-13: 978-1-906717-34-6

Soon it should appear on Amazon and bookshops around the world. Now when someone asks me to send a CV I can send them a link to buy it.

- Dmitry Vostokov @ DumpAnalysis.org -

OpenTask, a publisher of my books, is about to release a notebook for bloggers. For details please visit the page:

Idea: Blogger’s Notebook

I found it indispensable to keep track of my own blog post ideas in a hardcopy format, work on several blog transformations into books and simultaneously keep track of work and home-related tasks.

- Dmitry Vostokov @ DumpAnalysis.org -

Noticed that my blog is clearly visible from outside my apartment window even in daylight:

- Dmitry Vostokov @ DumpAnalysis.org -

“Avoid” crashes and hangs, “but do not seek” total stability “- nothing so expensive as” total stability.

Sydney Smith, A Memoir of the Reverend Sydney Smith by his daughter, Lady Holland, with a Selection from his Letters

- Dmitry Vostokov @ DumpAnalysis.org -

Because of large book density on my table disasters are inevitable. And it happened a month ago. I spilled coffee. One bottom level book sank like Titanic. The book on top of it which I was browsing at that moment survived heavily damaged: 

Recently I noticed that spilled coffee left a mark on one book side. It is clearly visible ”1“ on the picture above.

- Dmitry Vostokov @ DumpAnalysis.org - 

“How can you say my” computation “is not a success?” Has it “not for more than sixty” days “got enough to” process “and escaped being” crashed?

Logan Pearsall Smith, Last Words

- Dmitry Vostokov @ DumpAnalysis.org -

Recently I got another manual complete memory dump from a hang workstation where default analysis pointed to a possibility for a Spiking Thread pattern:

0: kd> !analyze -v
[...]
MANUALLY_INITIATED_CRASH (e2)
The user manually initiated this crash dump.
Arguments:
Arg1: 00000000
Arg2: 00000000
Arg3: 00000000
Arg4: 00000000
[...]
GetContextState failed, 0x80070026
Unable to read selector for PCR for processor 1
GetContextState failed, 0x80070026
Unable to read selector for PCR for processor 1

PROCESS_NAME:  AppA.exe

CURRENT_IRQL:  0

LAST_CONTROL_TRANSFER:  from 808b73a4 to 808b72cb

STACK_TEXT: 
f46f5b44 808b73a4 e1a36008 00000004 00000018 nt!HvpFindFreeCellInThisViewWindow+0xd7
f46f5b6c 808bd07b e1a36008 00000002 00000018 nt!HvpFindFreeCell+0x98
f46f5b98 808bd588 e1a36008 e1a362fc 00000000 nt!HvpDoAllocateCell+0x69
f46f5bbc 808d0b22 e1a36008 009214a0 c94e24a4 nt!HvReallocateCell+0x9a
f46f5bdc 808c1028 e1a36008 051fa3e8 00000003 nt!CmpAddValueToList+0x46
f46f5c28 808c406a e1a36008 cddb7ccc f46f5d0c nt!CmpSetValueKeyNew+0xfa
f46f5cb4 808b7e2f e45872e0 f46f5d0c 00000004 nt!CmSetValueKey+0x426
f46f5d44 8088978c 00000438 0012fad0 00000000 nt!NtSetValueKey+0x241
f46f5d44 7c8285ec 00000438 0012fad0 00000000 nt!KiFastCallEntry+0xfc
0012fa58 7c827b7b 77f77703 00000438 0012fad0 ntdll!KiFastSystemCallRet
0012fa5c 77f77703 00000438 0012fad0 00000000 ntdll!ZwSetValueKey+0xc
0012faa0 77f5ec90 00000438 0012fad0 00000004 ADVAPI32!LocalBaseRegSetValue+0x12c
0012fb04 60072e40 00000438 6290c0c4 00000000 ADVAPI32!RegSetValueExA+0x160
WARNING: Stack unwind information not available. Following frames may be wrong.
0012fbf4 628e2d57 60062e70 60062b40 80000001 DLLA!GetObjectId+0×9600
[…]

FOLLOWUP_IP:
nt!HvpFindFreeCellInThisViewWindow+d7
808b72cb 034508          add     eax,dword ptr [ebp+8]

Looking at this thread information we see it RUNNING (this is also evident from its call stack):

0: kd> !thread
THREAD 8a0b2890  Cid 0814.10e8  Teb: 7ffdf000 Win32Thread: bc217c68 RUNNING on processor 0
Not impersonating
DeviceMap                 e440acc0
Owning Process            8a0d85f8       Image:         AppA.exe
Wait Start TickCount      153974         Ticks: 0
Context Switch Count      16905                 LargeStack
UserTime                  00:00:03.109
KernelTime                00:00:17.500
[…]

We also see that the thread accumulated 17 seconds as time spent in kernel. Switching to AppA process context and looking at its Image version we see that it is 5.80.x:

0: kd> lmv m AppA
start    end        module name
00400000 0049c000   AppA   (deferred)            
    Image path: C:\PROGRA~1\AppA\AppA.exe
    Image name: AppA.exe
    Timestamp:        Thu Jun 05 14:51:52 2008 (4847EF78)
    CheckSum:         0009D068
    ImageSize:        0009C000
    File version:     5.80.5.1764
    Product version:  5.80.0.0

However from Google search we can find that there is newer version available (variant of Not My Version pattern) and even some indication on various forums that the older ones had problems with CPU resource utilization. We may stop here but I usually scan all threads for any suspicious signs and we can see another running thread on the second CPU:

THREAD 8a2ed5d0  Cid 11b4.1100  Teb: 7ffdf000 Win32Thread: bc342b80 RUNNING on processor 1
Not impersonating
DeviceMap                 e44fc100
Owning Process            8a1efcb0       Image:         calc.exe
Wait Start TickCount      153973         Ticks: 1 (0:00:00:00.015)
Context Switch Count      50736                 LargeStack
UserTime                  00:01:04.515
KernelTime                00:00:00.015
Win32 Start Address calc (0×0101e23a)
Start Address kernel32!BaseProcessStartThunk (0×77e617f8)
Stack Init f4cd6000 Current f4cd5d00 Base f4cd6000 Limit f4cd1000 Call 0
Priority 6 BasePriority 6 PriorityDecrement 0
Unable to get context for thread running on processor 1, Win32 error 0n38

We also see that this thread spent more than a minute in user mode. Unfortunately we cannot see its thread stack because the dump shows signs of Truncated Dump pattern:

Loading Dump File [MEMORY.DMP]
Kernel Complete Dump File: Full address space is available

************************************************************
WARNING: Dump file has been truncated.  Data may be missing.
************************************************************
[…]

0: kd> ~1
GetContextState failed, 0×80070026
Unable to read selector for PCR for processor 1
WARNING: Unable to reset page directories
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
Unable to get program counter
GetContextState failed, 0×80070026
Unable to get current machine context, Win32 error 0n38
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026

The dump file size 4,177,920 Kb is less than amount of physical memory 4,192,948 Kb:

1: kd> !vm
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
Unable to get program counter

*** Virtual Memory Usage ***
 Physical Memory:     1048237 (   4192948 Kb)
 Page File: \??\R:\pagefile.sys
   Current:   4177920 Kb  Free Space:   4154440 Kb
   Minimum:   4177920 Kb  Maximum:      4194304 Kb

We can stop here and still recommend to upgrade AppA product seen from the thread running on the first processor but the fact that the second thread belongs to innocent calc.exe demands some attention. Was it calculating incessantly some financial figures following button clicks from a financial genius? Taking advantage of a complete memory dump and the fact that this process spent most of the time in user space we can check for Hooked Functions pattern:

1: kd> .process /r /p 8a1efcb0
Implicit process is now 8a1efcb0
Loading User Symbols
..........................
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026

1: kd> !chkimg -lo 50 -d !user32 -v
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
GetContextState failed, 0x80070026
Unable to get program counter
Searching for module with expression: !user32
Will apply relocation fixups to file used for comparison
Will ignore NOP/LOCK errors
Will ignore patched instructions
Image specific ignores will be applied
Comparison image path: c:\mss\USER32.dll\45D70AC791000\USER32.dll
No range specified

Scanning section:    .text
Size: 392891
Range to scan: 77381000-773e0ebb
    7738c341-7738c345  5 bytes - USER32!CreateWindowExA
 [ 8b ff 55 8b ec:e9 ba 3c 00 c0 ]
[…]
Total bytes compared: 73728(18%)
Number of errors: 75
75 errors : !user32 (7738c341-773a154d)
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026

1: kd> u 7738c341
USER32!CreateWindowExA:
7738c341 e9ba3c00c0      jmp     37390000
7738c346 6801000040      push    40000001h
7738c34b ff7534          push    dword ptr [ebp+34h]
7738c34e ff7530          push    dword ptr [ebp+30h]
7738c351 ff752c          push    dword ptr [ebp+2Ch]
7738c354 ff7528          push    dword ptr [ebp+28h]
7738c357 ff7524          push    dword ptr [ebp+24h]
7738c35a ff7520          push    dword ptr [ebp+20h]
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026

1: kd> u 37390000
37390000 e96b91562e      jmp     HookA!CreateWindowExA (658f9170)
37390005 8bff            mov     edi,edi
37390007 55              push    ebp
37390008 8bec            mov     ebp,esp
3739000a e937c3ff3f      jmp     USER32!CreateWindowExA+0×5 (7738c346)
3739000f 0000            add     byte ptr [eax],al
37390011 0000            add     byte ptr [eax],al
37390013 0000            add     byte ptr [eax],al
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026
GetContextState failed, 0×80070026

Indeed we see that HookA module is involved and we can recommend to test the stability of the system without the product that uses it or upgrading or disabling this component.

- Dmitry Vostokov @ DumpAnalysis.org -

OpenTask, a publisher of my books, is about to release a notebook for small and self-publishers. It’s title is Title itself. For details please visit the page:

Title: Book Publisher’s Notebook

I found it indispensable to keep track of my own book titles and their book data in a hardcopy format.

- Dmitry Vostokov @ DumpAnalysis.org -

“To” debug “is to” code “twice.”

Joseph Joubert, Pensées

- Dmitry Vostokov @ DumpAnalysis.org -

“Impatient” engineers “always” debug “too late.”

Jean Gwenaël Dutourd, Le Fond et la Forme, essai alphabétique sur la morale et sur le style

- Dmitry Vostokov @ DumpAnalysis.org -

A number of writers expressed their wishes to be a co-author of the forthcoming SF novel Googol Dump. I have selected Dun Bugmons for his name sounding like Dún Laoghaire where I live nearby by walking distance in Monkstown and his surname accidentally reminding me of Bug Monitors. Please join me in congratulating Dun Bugmons!

- Dmitry Vostokov @ DumpAnalysis.org -

While working on WinDbg command cards and even before that when compiling a comparison table for both WinDbg and GDB I came to an idea of abstract debugging commands that correspond to common debugging tasks, have clear syntax and semantics and serve metaphorically as a basis for conversion of analog thinking to digital debugger assistance (see analog-to-digital conversion for ADC abbreviation). Here a WinDbg extension can help but now I think about using a tree-based approach similar to CMDTREE.TXT for CDA Checklist. More on this later. Any comments or suggestions are greatly appreciated.

- Dmitry Vostokov @ DumpAnalysis.org -

When we have tool commands that sound similar to English words like common root French or German vocabulary to English why not to leverage time-proven foreign language learning techniques:

WinDbg: A Reference Poster and Learning Cards

- Dmitry Vostokov @ DumpAnalysis.org -

Suddenly the course of my publishing activities bended a little to produce a DIY poster and learning cards to be published soon. Here are the product details:

Annotation:
WinDbg is a powerful debugger from Microsoft Debugging Tools for Windows. It has more than 350 commands that can be used in different debugging scenarios. The cover of this book is a poster featuring crash dump analysis checklist and common patterns seen in memory dumps and live debugging sessions. Inside the book you can find ready to cut learning cards with commands and their descriptions coloured according to their use for crash dump or live debugging sessions and user, kernel or complete memory dumps. Tossing cards can create unexpected connections between commands and help to learn them more quickly. Uncut pages can also serve as birds eye view to WinDbg debugging capabilities. More than 350 WinDbg commands including meta-commands and extensions are included.

• Title: WinDbg: A Reference Poster and Learning Cards
• Authors: Dmitry Vostokov
• Publisher: Opentask (20 November 2008)
• Language: English
• Product Dimensions: 28.0 x 21.6
• ISBN-13: 978-1-906717-29-2
• Paperback: 20 pages

Book Excerpt

Front cover:

Back cover:

After you take inside pages out you are left with a cover that you can use as a crash dump analysis checklist and patterns poster:

I also plan to update this book on a yearly basis. 

- Dmitry Vostokov @ DumpAnalysis.org -

Another example of Wait Chain pattern for objects with ownership semantics is seen in kernel and complete memory dumps where threads are waiting for thread objects. A thread object is a synchronization object whose owner is a thread so they can be easily identified. For example, the main application thread is waiting for an object:

1: kd> !thread 8818e660 16
THREAD 8818e660  Cid 1890.1c50  Teb: 7ffdf000 Win32Thread: b8411008 WAIT: (Unknown) UserMode Non-Alertable
    87d569d8  Thread
    8818e6d8  NotificationTimer
Not impersonating
DeviceMap                 e10008d8
Owning Process            87db5d88       Image:         App.exe
Wait Start TickCount      299006         Ticks: 255 (0:00:00:03.984)
Context Switch Count      1208                 LargeStack
UserTime                  00:00:00.203
KernelTime                00:00:00.203
Start Address kernel32!BaseThreadStartThunk (0×77e617ec)
Stack Init b42c3000 Current b42c2c60 Base b42c3000 Limit b42be000 Call 0
Priority 15 BasePriority 15 PriorityDecrement 0
ChildEBP RetAddr  Args to Child             
b42c2c78 80833e8d 8818e660 8818e708 00000003 nt!KiSwapContext+0×26
b42c2ca4 80829b74 00000000 b42c2d14 00000000 nt!KiSwapThread+0×2e5
b42c2cec 8093b034 87d569d8 00000006 00804c01 nt!KeWaitForSingleObject+0×346
b42c2d50 8088ac4c 000001ec 00000000 b42c2d14 nt!NtWaitForSingleObject+0×9a
b42c2d50 7c8285ec 000001ec 00000000 b42c2d14 nt!KiFastCallEntry+0xfc
0006fde4 7c827d0b 77e61d1e 000001ec 00000000 ntdll!KiFastSystemCallRet
0006fde8 77e61d1e 000001ec 00000000 0006fe2c ntdll!NtWaitForSingleObject+0xc
0006fe58 77e61c8d 000001ec 00001388 00000000 kernel32!WaitForSingleObjectEx+0xac
0006fe6c 01039308 000001ec 00001388 00000000 kernel32!WaitForSingleObject+0×12
0006fe94 010204ac 0007cc00 00000001 00000002 App!WaitForNotifyList+0xf2
[…]

However that object is a thread too:

THREAD 87d569d8  Cid 1890.1ec0  Teb: 7ffd9000 Win32Thread: b869ba48 WAIT: (Unknown) UserMode Non-Alertable
    8a1f8870  Thread

Therefore, we see that thread 8818e660 is waiting for another thread 87d569d8 which belongs to the same process with PID 1890 and thread 87d569d8 itself is waiting for thread 8a1f8870 which has the following stack trace:

1: kd> !thread 8a1f8870 16
THREAD 8a1f8870  Cid 1890.07d8  Teb: 7ff95000 Win32Thread: 00000000 WAIT: (Unknown) UserMode Non-Alertable
    8a0ce4c0  NotificationEvent
    886f1870  NotificationEvent
Not impersonating
DeviceMap                 e10008d8
Owning Process            87db5d88       Image:         App.exe
Wait Start TickCount      292599         Ticks: 6662 (0:00:01:44.093)
Context Switch Count      17            
UserTime                  00:00:00.000
KernelTime                00:00:00.000
Win32 Start Address Dll!StartMonitoring (0×758217b8)
Start Address kernel32!BaseThreadStartThunk (0×77e617ec)
Stack Init b6d4f000 Current b6d4e900 Base b6d4f000 Limit b6d4c000 Call 0
Priority 14 BasePriority 13 PriorityDecrement 0
ChildEBP RetAddr  Args to Child             
b6d4e918 80833e8d 8a1f8870 00000002 00140000 nt!KiSwapContext+0×26
b6d4e944 808295ab 8a1f8870 00000002 00000000 nt!KiSwapThread+0×2e5
b6d4e978 8093b290 00000002 b6d4eaac 00000001 nt!KeWaitForMultipleObjects+0×3d7
b6d4ebf4 8093b3f2 00000002 b6d4ec1c 00000001 nt!ObpWaitForMultipleObjects+0×202
b6d4ed48 8088ac4c 00000002 026bfc08 00000001 nt!NtWaitForMultipleObjects+0xc8
b6d4ed48 7c8285ec 00000002 026bfc08 00000001 nt!KiFastCallEntry+0xfc
026bfbb8 7c827cfb 77e6202c 00000002 026bfc08 ntdll!KiFastSystemCallRet
026bfbbc 77e6202c 00000002 026bfc08 00000001 ntdll!NtWaitForMultipleObjects+0xc
026bfc64 77e62fbe 00000002 026bfca4 00000000 kernel32!WaitForMultipleObjectsEx+0×11a
026bfc80 6554a01f 00000002 026bfca4 00000000 kernel32!WaitForMultipleObjects+0×18
026bfcfc 758237a3 cd050002 ffffffff 026bfd4c Dll!GetStatusChange+0×7bf
026bffb8 77e64829 75833120 00000000 00000000 Dll!StartMonitoring+0×14b
026bffec 00000000 758217b8 75833120 00000000 kernel32!BaseThreadStart+0×34

Thread 8a1f8870 is waiting for two notification events disjointly which is confirmed by dumping WaitForMultipleObjects arguments. Neither of them is in signaled state and one is a named event “MyEventObject”:

1: kd> dd 026bfc08 l2
026bfc08  0000008c 00000084

1: kd> !handle 0000008c
processor number 1, process 87db5d88
PROCESS 87db5d88  SessionId: 4  Cid: 1890    Peb: 7ffdc000  ParentCid: 01d0
    DirBase: cfe438e0  ObjectTable: e178c228  HandleCount: 439.
    Image: App.exe

Handle table at e50d2000 with 439 Entries in use
008c: Object: 8a0ce4c0  GrantedAccess: 001f0003 Entry: e50d2118
Object: 8a0ce4c0  Type: (8b26ec00) Event
    ObjectHeader: 8a0ce4a8 (old version)
        HandleCount: 1  PointerCount: 3

1: kd> !handle 00000084
processor number 1, process 87db5d88
PROCESS 87db5d88  SessionId: 4  Cid: 1890    Peb: 7ffdc000  ParentCid: 01d0
    DirBase: cfe438e0  ObjectTable: e178c228  HandleCount: 439.
    Image: App.exe

Handle table at e50d2000 with 439 Entries in use
0084: Object: 886f1870  GrantedAccess: 001f0003 (Inherit) Entry: e50d2108
Object: 886f1870  Type: (8b26ec00) Event
    ObjectHeader: 886f1858 (old version)
        HandleCount: 1  PointerCount: 4
        Directory Object: e43ee320  Name: MyEventObject

1: kd> dt _DISPATCHER_HEADER 8a0ce4c0
cutildll!_DISPATCHER_HEADER
   +0×000 Type             : 0 ”
   +0×001 Absolute         : 0 ”
   +0×002 Size             : 0×4 ”
   +0×003 Inserted         : 0 ”
   +0×003 DebugActive      : 0 ”
   +0×000 Lock             : 262144
   +0×004 SignalState      : 0
   +0×008 WaitListHead     : _LIST_ENTRY [ 0×88519d18 - 0×8a1f8918 ]

1: kd> dt _DISPATCHER_HEADER 886f1870
cutildll!_DISPATCHER_HEADER
   +0×000 Type             : 0 ”
   +0×001 Absolute         : 0 ”
   +0×002 Size             : 0×4 ”
   +0×003 Inserted         : 0 ”
   +0×003 DebugActive      : 0 ”
   +0×000 Lock             : 262144
   +0×004 SignalState      : 0
   +0×008 WaitListHead     : _LIST_ENTRY [ 0×88519d30 - 0×8a1f8930 ]

Here is a diagram showing this wait chain:

- Dmitry Vostokov @ DumpAnalysis.org -

CtxHideEx32 tool has been updated to the version 1.1 and can be downloaded from Citrix support. It now allows a substring search for a window title or class, for example:

CtxHideEx32.exe HIDE "*error" "" OK

As by-product coupled with an optional command line I discovered that it allows to automatically dump any process displaying a message box with an error message in its window title. Here is an example using TestDefaultDebugger64 to simulate an application fault message where the following instance of CtxHideEx32 was setup to dump a process showing WER dialog on Vista:

CtxHideEx32.exe NONE "*Microsoft Windows" "" "C:\kktools\userdump8.1\x64\userdump.exe %d"

We click on a big lightning button:

and then WER dialog appears:

Immediately CtxHideEx32 kicks in and starts dumping the owner process incessantly so you better to dismiss this dialog by choosing something:

We see it was WerFault.exe. 

Note: I think I have to amend CtxHideEx32 to make it wait until the spawned command line interpreter finishes its job. Stay tuned.

- Dmitry Vostokov @ DumpAnalysis.org -