TTD Heap Objects
Description
TTD Heap objects are used to give information about heap calls that occur over the course of a trace.
Properties
Every heap object will have these properties.
| Property | Description |
|---|---|
| Action | Describes the action that occurred. Possible values are: Alloc, ReAlloc, Free, Create, Protect, Lock, Unlock, Destroy. |
| Heap | The handle for the Win32 heap. |
Conditional properties
Depending on the heap object, it may have some of the properties below.
| Property | Description |
|---|---|
| Address | The address of the allocated object. |
| PreviousAddress | The address of the allocated object before it was reallocated. If Address is not the same as PreviousAddress then the reallocation caused the memory to move. |
| Size | The size and/or requested size of an allocated object. |
| BaseAddress | The address of an allocated object in the heap. It can represent the address which will be freed (Free) or the address of the object before it is reallocated (ReAlloc.) |
| Flags | Meaning depends on the API. |
| Result | The result of the heap API call. Non-zero means success and zero means failure. |
| ReserveSize | Amount of memory to reserve for the heap. |
| CommitSize | Initial committed size for the heap. |
| MakeReadOnly | A non-zero value indicates a request to make the heap read-only; A zero value indicates the heap should be read-write. |
Children
| Object | Description |
|---|---|
| TimeStart | A position object that describes the position at the start of the allocation. |
| TimeEnd | A position object that describes the position at the end of the allocation. |
Example Usage
Use this dx (Display Debugger Object Model Expression) command to display the heap memory in a grid using the -g option.
0:0:000> dx -g @$cursession.TTD.Data.Heap()
=======================================================================================================================================================
= = Action = Heap = Address = Size = Flags = (+) TimeStart = (+) TimeEnd = Result = PreviousAddress =
=======================================================================================================================================================
= [0x0] : [object Object] - Alloc - 0xaf0000 - 0xb0cfd0 - 0x4c - 0x0 - FAB:17B1 - FAD:40 - - =
= [0x1] : [object Object] - Alloc - 0xaf0000 - 0xb07210 - 0x34 - 0x8 - FB1:9 - FB3:74 - - =
= [0x2] : [object Object] - Alloc - 0xaf0000 - 0xb256d8 - 0x3c - 0x8 - E525:174 - E526:E1 - - =
The output can be described as “normalized data” because there is a chosen set of APIs that represent heap operations. The data that is extracted from the appropriate parameters, is presented in a uniform manner.
Clicking on TimeStart or TimeEnd will navigate you to that point in the trace.
Click on the parameters field next to a specific entry, to display available parameter information.
dx -r1 @$cursession.TTD.Data.Heap()[2].@"Parameters"
@$cursession.TTD.Data.Heap()[2].@"Parameters"
[0x0] : 0x16c7d780000
[0x1] : 0x280000
[0x2] : 0x20
[0x3] : 0x0
...
Increase the recursion -r value to display additional information.
See Also
Time Travel Debugging - Introduction to Time Travel Debugging objects