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!obtrace

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The !obtrace extension displays object reference tracing data for the specified object.

!obtrace Object

Parameters

Object
A pointer to the object or a path.

DLL

Kdexts.dll

Additional Information

For more information about the Global Flags utility (GFlags), see the Windows Driver Kit (WDK) documentation and Microsoft Windows Internals by Mark Russinovich and David Solomon.

Remarks

The object reference tracing feature of Windows records sequential stack traces whenever an object reference counter is incremented or decremented.

Before using this extension to display object reference tracing data, you must use GFlags to enable object reference tracing for the specified object. You can enable object reference tracing as a kernel flag (run-time) setting, in which the change is effective immediately, but disappears if you shut down or restart; or as a registry setting, which requires a restart, but remains effective until you change it.

Here is an example of the output from the !obtrace extension:

kd> !obtrace 0xfa96f700
Object: fa96f700        Image: cmd.exe
Sequence  (+/-)  Stack
--------  -----  ---------------------------------------------------
   2421d    +1  nt!ObCreateObject+180
                nt!NtCreateEvent+92
                nt!KiFastCallEntry+104
                nt!ZwCreateEvent+11
                win32k!UserThreadCallout+6f
                win32k!W32pThreadCallout+38
                nt!PsConvertToGuiThread+174
                nt!KiBBTUnexpectedRange+c

   2421e    -1  nt!ObfDereferenceObject+19
                nt!NtCreateEvent+d4
                nt!KiFastCallEntry+104
                nt!ZwCreateEvent+11
                win32k!UserThreadCallout+6f
                win32k!W32pThreadCallout+38
                nt!PsConvertToGuiThread+174
                nt!KiBBTUnexpectedRange+c

   2421f    +1  nt!ObReferenceObjectByHandle+1c3
                win32k!xxxCreateThreadInfo+37d
                win32k!UserThreadCallout+6f
                win32k!W32pThreadCallout+38
                nt!PsConvertToGuiThread+174
                nt!KiBBTUnexpectedRange+c

   24220    +1  nt!ObReferenceObjectByHandle+1c3
                win32k!ProtectHandle+22
                win32k!xxxCreateThreadInfo+3a0
                win32k!UserThreadCallout+6f
                win32k!W32pThreadCallout+38
                nt!PsConvertToGuiThread+174
                nt!KiBBTUnexpectedRange+c

   24221    -1  nt!ObfDereferenceObject+19
                win32k!xxxCreateThreadInfo+3a0
                win32k!UserThreadCallout+6f
                win32k!W32pThreadCallout+38
                nt!PsConvertToGuiThread+174
                nt!KiBBTUnexpectedRange+c

----  ----------------------------------------------------------
References: 3, Dereferences 2

The primary indicators in the !obtrace 0xfa96f700 display are listed in the following table.

Parameter Meaning

Sequence

Represents the order of operations.

+/-

Indicates a reference or a dereference operation.

+1 indicates a reference operation.

-1 indicates a dereference operation.

+/- n indicates multiple reference/dereference operations.

The object reference traces on x64-based target computers might be incomplete because it is not always possible to acquire stack traces at IRQL levels higher than PASSIVE_LEVEL.

You can stop execution at any time by pressing CTRL+BREAK (in WinDbg) or CTRL+C (in KD).