Slicer3:VTK Leak Debugging - Revision history

Pieper: /* Print additional object info upon object creation using breakpoints (Windows-only) */

2011-11-14T22:16:07Z

Print additional object info upon object creation using breakpoints (Windows-only)

Lasso at 21:32, 14 November 2011

2011-11-14T21:32:02Z

Lasso: Moved subsection to other section

2011-11-14T21:31:45Z

Moved subsection to other section

Lasso: Added further tips and tricks for memory leak prevention and analysis

2011-11-14T21:30:18Z

Added further tips and tricks for memory leak prevention and analysis

Pieper at 17:35, 5 December 2008

2008-12-05T17:35:29Z

Marianna: 1 revision

2008-05-15T17:54:01Z

1 revision

Pieper at 18:49, 27 January 2007

2007-01-27T18:49:12Z

New page

If you are getting leaks for a vtkObject but can't figure out where it's coming from, you can try making a change to the constructor for that class and checking the debug output (warning, it can be verbose). What you will see from the following type of change is instances that are created but never destroyed. Then you can add other debug statements in your code and narrow down which instances aren't being deleted.

Add this at the beginning of the constructor:
this->DebugOn();
vtkDebugMacro("constructing");

and this in the destructor:
vtkDebugMacro("destructing");

For example, these changes helped me find an extra instance of vtkPoints

<pre>
// Construct object with an initial data array of type float.
vtkPoints::vtkPoints(int dataType)
{
this->DebugOn();
vtkDebugMacro("constructing");
this->Data = vtkFloatArray::New();
this->Data->Register(this);
this->Data->Delete();
this->SetDataType(dataType);

this->Data->SetNumberOfComponents(3);

this->Bounds[0] = this->Bounds[2] = this->Bounds[4] = 0.0;
this->Bounds[1] = this->Bounds[3] = this->Bounds[5] = 1.0;
}

vtkPoints::~vtkPoints()
{
vtkDebugMacro("destructing");
this->Data->UnRegister(this);
}
</pre>

@@ Line 41: / Line 41: @@
 ====Print additional object info upon object creation using breakpoints (Windows-only)====
 One approach that has worked for me is to modify the behavior of visual studio breakpoints - right clicking on a breakpoint and picking the 'When Hit..." option allow you to do things like print an expression or stack trace and continue running.  This does slow down execution but can provide useful log data without modifying the code.
 ===Preventing memory leaks===

@@ Line 134: / Line 134: @@
 </pre>
-====Saving pointers to leaked objects====
+===Saving pointers to leaked objects===
 With a small VTK patch you can get the pointers to the actual leaked object instances. Then, using the pointers, you can print the contents, analyze the object with the debugger, etc.  The idea is to simply add the object pointer to a std::set when in the vtkObject constructor, remove the pointer from the std::set in the destructor, and print the pointers in vtkDebugLeaks. The implementation requires minor modification of 3 files, for VTK-5.8.0 a patch/modified files are available at the NA-MIC sandbox: http://svn.na-mic.org/NAMICSandBox/trunk/SlicerDebug/DebugLeakAnalysis/VTK-5.8.0/

@@ Line 38: / Line 38: @@
+}
 </pre>
 ====Print additional object info upon object creation using breakpoints (Windows-only)====
@@ Line 65: / Line 61: @@
 == In VTK ==
 In VTK/Common/vtkObjectBase.cxx, modify the RegisterInternal and UnRegisterInternal methods as follows.  The prints to cerr will provide a running list of all memory allocation activity.  To make this even more useful, you may want to change places in your code (and VTK code) from o->Delete() to o->UnRegister(this).
@@ Line 135: / Line 133: @@
 </pre>

@@ Line 1: / Line 1: @@
 ==In your code==
 If you are getting leaks for a vtkObject but can't figure out where it's coming from, you can try making a change to the constructor for that class and checking the debug output (warning, it can be verbose).  What you will see from the following type of change is instances that are created but never destroyed.  Then you can add other debug statements in your code and narrow down which instances aren't being deleted.
@@ Line 35: / Line 38: @@
+}
 </pre>
 == In VTK ==

← Older revision	Revision as of 17:54, 15 May 2008
(No difference)