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

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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)
 
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:
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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()
 
  (gdb) break vtkProperty2D::vtkProperty2D()
 
  Breakpoint 1 at 0x5b22d0e55d04296: file vtkProperty2D.cxx, line 22
 
  Breakpoint 1 at 0x5b22d0e55d04296: file vtkProperty2D.cxx, line 22

Revision as of 21:38, 27 December 2011

Home < Documentation < 4.0 < Developers < Tutorials < Troubleshooting


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. ...
  4. Find what specific instance of a class (here vtkProperty2D) leaks.
  5. 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 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.
  6. 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();