Difference between revisions of "Documentation/4.0/Developers/Tutorials/Troubleshooting"

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{{documentation/underconstruction}}
 
{{documentation/underconstruction}}
 +
Here are some tips to narrow down various issues such as crash, or memory leaks
  
−
* Disable plugins
+
=Disable features=
 +
Try running Slicer with as few features as possible:
 +
* Disable Slicer options via the command line
 +
*: <pre>$ ./Slicer --no-splash --ignore-slicerrc --disable-cli-module --disable-loadable-module --disable-scriptedmodule</pre>
 +
** Look at all the possible options
 +
**: <pre>$ ./Slicer --help</pre>
 +
* Disable ITK plugins
 +
*: CLI modules silently load the ITK plugins in lib/Slicer-4.0/ITKFactories. These plugins are used to share the volumes between Slicer and the ITK filter without having to copy them on disk.
 
** rename lib/Slicer-4.0/ITKFactories into lib/Slicer-4.0/ITKFactories-disabled
 
** rename lib/Slicer-4.0/ITKFactories into lib/Slicer-4.0/ITKFactories-disabled
 +
* Disable Qt plugins
 +
** rename lib/Slicer-4.0/iconengine into lib/Slicer-4.0/iconengine-disabled
 +
 +
=Track memory leaks=
 +
<ol>
 +
<li> Turn ON the VTK_DEBUG_LEAKS CMake variable and build Slicer</li>
 +
<li> Create a test that reproduces the memory leak systematically </li>
 +
After execution, the memory leaks are printed automatically by VTK on the standard output:
 +
224: vtkDebugLeaks has detected LEAKS!
 +
224: Class "vtkProperty2D" has 60 instances still around.
 +
...
 +
<li>Find what specific instance of a class (here vtkProperty2D) leaks.</li>
 +
If the class is instantiated a large amount of time, it is hard to know what instance is leaking.
 +
You can edit the constructor and destructor of the class (here vtkProperty2D::vtkProperty2D() and vtkProperty2D::~vtkProperty2D())
 +
vtkProperty2D::vtkProperty2D()
 +
{
 +
...
 +
static int count = 0;
 +
std::cout << "CREATE vtkProperty2D instance #" << count++ << " " << this << std::endl;
 +
}
 +
 +
vtkProperty2D::~vtkProperty2D()
 +
{
 +
...
 +
static int count = 0;
 +
std::cout << "DELETE vtkProperty2D instance #" << count++ << " " << this << std::endl;
 +
}
 +
Don't forget to rebuild VTK if the class is from VTK (and not just Slicer inner build)
 +
After running the test again, you should see a list of
 +
...
 +
CREATE vtkProperty2D instance #0 0x0123456
 +
...
 +
CREATE vtkProperty2D instance #1 0x01234E5
 +
...
 +
DELETE vtkProperty2D instance #0 0x0123456
 +
...
 +
DELETE vtkProperty2D instance #1 0x01234E5
 +
...
 +
CREATE vtkProperty2D instance #2 0x0123A23
 +
...
 +
CREATE vtkProperty2D instance #3 0x0124312
 +
...
 +
Copy/paste the listing in a text editor and ensure that for each CREATE of a pointer (e.g. 0x0123456) it exists a DELETE. If there isn't, you found what instance is leaking. Note the instance # (here instance #2 and #3)
 +
Run the test with the [[Documentation/4.0/Developers/Tutorials/Debug_Instructions debugger]], set a breakpoint in the class constructor and ignore the break as many time as the instance number:
 +
(gdb) break vtkProperty2D::vtkProperty2D()
 +
Breakpoint 1 at 0x5b22d0e55d04296: file vtkProperty2D.cxx, line 22
 +
(gdb) ignore 1 2
 +
When the debugger stops, check the call stack:
 +
(gdb) backtrace
 +
By analyzing the trace, you should be able to find the faulty instance.
 +
</li>
 +
<li> Analyze the code to see where the leak could be
 +
Here is a listing of the most common mistakes
 +
* this->MyXXX = vtkXXX::New();
 +
** Is there a matching this->MyXXX->Delete() ?
 +
** Are you sure <code>this->MyXXX</code> is <code>0</code> before being assigned a new pointer ?  If not, then you need to add
 +
if (this->MyXXX != 0)
 +
  {
 +
  this->MyXXX->Delete();
 +
  this->MyXXX = 0;
 +
  }
 +
  this->MyXXX = vtkXXX::New();
 +
</li>
 +
</ol>
 +
{{ombox
 +
|type=content
 +
|text=To reduce memory leaks, use the following tools:
 +
* <code>vtkNew<vtkXXX> myXXX;</code>,
 +
* <code>vtkSmartPointer<vtkXXX> myXXX = vtkSmartPointer<vtkXXX>::New()</code>
 +
* and <code>vtkSmartPointer<vtkXXX> myXXX; myXXX.TakeReference(this->CreateObjAndCallerOwnsReference())</code>.
 +
}}

Revision as of 21:36, 27 December 2011

Home < Documentation < 4.0 < Developers < Tutorials < Troubleshooting
Work in progress
 Page under construction.


Here are some tips to narrow down various issues such as crash, or memory leaks

Disable features

Try running Slicer with as few features as possible:

  • Disable Slicer options via the command line 
    $ ./Slicer --no-splash --ignore-slicerrc --disable-cli-module --disable-loadable-module --disable-scriptedmodule
    • Look at all the possible options 
      $ ./Slicer --help
  • Disable ITK plugins
    CLI modules silently load the ITK plugins in lib/Slicer-4.0/ITKFactories. These plugins are used to share the volumes between Slicer and the ITK filter without having to copy them on disk.
    • rename lib/Slicer-4.0/ITKFactories into lib/Slicer-4.0/ITKFactories-disabled
  • Disable Qt plugins
    • rename lib/Slicer-4.0/iconengine into lib/Slicer-4.0/iconengine-disabled

Track memory leaks

  1. Turn ON the VTK_DEBUG_LEAKS CMake variable and build Slicer
  2. Create a test that reproduces the memory leak systematically
    3. After execution, the memory leaks are printed automatically by VTK on the standard output: 224: vtkDebugLeaks has detected LEAKS! 224: Class "vtkProperty2D" has 60 instances still around. ...
  3. Find what specific instance of a class (here vtkProperty2D) leaks.
    4. If the class is instantiated a large amount of time, it is hard to know what instance is leaking. You can edit the constructor and destructor of the class (here vtkProperty2D::vtkProperty2D() and vtkProperty2D::~vtkProperty2D()) vtkProperty2D::vtkProperty2D() { ... static int count = 0; std::cout << "CREATE vtkProperty2D instance #" << count++ << " " << this << std::endl; } vtkProperty2D::~vtkProperty2D() { ... static int count = 0; std::cout << "DELETE vtkProperty2D instance #" << count++ << " " << this << std::endl; } Don't forget to rebuild VTK if the class is from VTK (and not just Slicer inner build) After running the test again, you should see a list of ... CREATE vtkProperty2D instance #0 0x0123456 ... CREATE vtkProperty2D instance #1 0x01234E5 ... DELETE vtkProperty2D instance #0 0x0123456 ... DELETE vtkProperty2D instance #1 0x01234E5 ... CREATE vtkProperty2D instance #2 0x0123A23 ... CREATE vtkProperty2D instance #3 0x0124312 ... Copy/paste the listing in a text editor and ensure that for each CREATE of a pointer (e.g. 0x0123456) it exists a DELETE. If there isn't, you found what instance is leaking. Note the instance # (here instance #2 and #3) Run the test with the Documentation/4.0/Developers/Tutorials/Debug_Instructions debugger, set a breakpoint in the class constructor and ignore the break as many time as the instance number: (gdb) break vtkProperty2D::vtkProperty2D() Breakpoint 1 at 0x5b22d0e55d04296: file vtkProperty2D.cxx, line 22 (gdb) ignore 1 2 When the debugger stops, check the call stack: (gdb) backtrace By analyzing the trace, you should be able to find the faulty instance.
  4. Analyze the code to see where the leak could be Here is a listing of the most common mistakes
    • this->MyXXX = vtkXXX::New();
      • Is there a matching this->MyXXX->Delete() ?
      • Are you sure this->MyXXX is 0 before being assigned a new pointer ? If not, then you need to add
    if (this->MyXXX != 0) { this->MyXXX->Delete(); this->MyXXX = 0; } this->MyXXX = vtkXXX::New();
To reduce memory leaks, use the following tools:
  • vtkNew<vtkXXX> myXXX;,
  • vtkSmartPointer<vtkXXX> myXXX = vtkSmartPointer<vtkXXX>::New()
  • and vtkSmartPointer<vtkXXX> myXXX; myXXX.TakeReference(this->CreateObjAndCallerOwnsReference()).
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