Documentation/4.0/Developers/Tutorials/Troubleshooting - Revision history

UpdateBot: Prepend documentation/versioncheck template. See http://na-mic.org/Mantis/view.php?id=2887

2013-06-14T07:34:36Z

Prepend documentation/versioncheck template. See http://na-mic.org/Mantis/view.php?id=2887

Nicole: /* Track a crash while accessing already deleted object pointer */

2012-03-15T14:28:46Z

Track a crash while accessing already deleted object pointer

Finetjul: /* Track a crash while accessing already deleted object pointer */

2012-02-29T18:32:50Z

Track a crash while accessing already deleted object pointer

Finetjul: Add track crash hint.

2012-02-29T18:27:24Z

Add track crash hint.

Finetjul: /* Track memory leaks */

2011-12-27T21:40:01Z

Track memory leaks

Finetjul: /* Track memory leaks */

2011-12-27T21:38:50Z

Track memory leaks

Finetjul at 21:36, 27 December 2011

2011-12-27T21:36:37Z

JChris.FillionR at 19:04, 20 December 2011

2011-12-20T19:04:51Z

Finetjul: Created page with '* Disable plugins ** rename lib/Slicer-4.0/ITKFactories into lib/Slicer-4.0/ITKFactories-disabled'

2011-12-11T02:49:43Z

Created page with '* Disable plugins ** rename lib/Slicer-4.0/ITKFactories into lib/Slicer-4.0/ITKFactories-disabled'

New page

* Disable plugins
** rename lib/Slicer-4.0/ITKFactories into lib/Slicer-4.0/ITKFactories-disabled

← Older revision		Revision as of 07:34, 14 June 2013
Line 1:		Line 1:
		+	<noinclude>{{documentation/versioncheck}}</noinclude>
	{{documentation/underconstruction}}		{{documentation/underconstruction}}
	Here are some tips to narrow down various issues such as crash, or memory leaks		Here are some tips to narrow down various issues such as crash, or memory leaks

@@ Line 91: / Line 91: @@
 Add in the object destructor (it can be in the base class (vtkObject or vtkMRMLNode) if you don't know the type):
   static int count = 0;
-  std::cout << "#######Object Destructed: " << this << count++ << std::endl;
+  std::cout << "#######Object Destructed: " << this << " " << count++ << std::endl;
 <li>Run the application and make it crash.</li>
 <li>In the logs you shall see something like that:</li>

@@ Line 83: / Line 83: @@
 =Track a crash while accessing already deleted object pointer=
-If the application crashes by accessing an invalid pointer. The goal here is to find when (and why) the pointer is deleted before it is accessed
+If the application crashes by accessing an invalid pointer. The goal here is to find when (and why) the pointer is deleted before it is accessed .
 <ol>
-<li> Before the crash, print the value of the pointer:
+<li>Before the crash, print the value of the pointer:</li>
-Add <code>std::cout << ">>>>>Object pointer: " << this->MyObject << std::endl;</code> before the crash (i.e. <code>this->MyObject->update()</code>)
+Add before the crash (i.e. <code>this->MyObject->update()</code>)
-</li>
+ std::cout << ">>>>>Object pointer: " << this->MyObject << std::endl;
-<li>Add a counter in the destructor:
+<li>Add a counter in the destructor:</li>
 Add in the object destructor (it can be in the base class (vtkObject or vtkMRMLNode) if you don't know the type):
   static int count = 0;
   std::cout << "#######Object Destructed: " << this << count++ << std::endl;
-</li>
+<li>Run the application and make it crash.</li>
-<li>Run the application and make it crash. In the logs you shall see something like that:
+<li>In the logs you shall see something like that:</li>
   #######Object Destructed: 0x12345678 0
   #######Object Destructed: 0x12345679 1
@@ Line 112: / Line 112: @@
   >>>>>Object Pointer: '''0x12345663'''
   Segfault
-</li>
+<li> Search in the logs when the pointer before crash has been deleted. Set a conditional breakpoint in the debugger:</li>
   (gdb) break MyObj.cxx:103 if count == 6
 or
@@ Line 119: / Line 118: @@
   (gdb) ignore 1 5
 or if you don't want to use a debugger, you can make it crash the 6th time:
-  assert(count != 6)
+  assert(count != 6);
 <li> Analyze the backtrace to understand why the pointer has been deleted without letting know the object that tries to access it.</li>

← Older revision		Revision as of 18:27, 29 February 2012
Line 81:		Line 81:
	* <code>vtkSmartPointer<vtkXXX> myXXX; myXXX.TakeReference(this->CreateObjAndCallerOwnsReference())</code>.		* <code>vtkSmartPointer<vtkXXX> myXXX; myXXX.TakeReference(this->CreateObjAndCallerOwnsReference())</code>.
	}}		}}
		+
		+	=Track a crash while accessing already deleted object pointer=
		+	If the application crashes by accessing an invalid pointer. The goal here is to find when (and why) the pointer is deleted before it is accessed
		+	<ol>
		+	<li> Before the crash, print the value of the pointer:
		+	Add <code>std::cout << ">>>>>Object pointer: " << this->MyObject << std::endl;</code> before the crash (i.e. <code>this->MyObject->update()</code>)
		+	</li>
		+	<li>Add a counter in the destructor:
		+	Add in the object destructor (it can be in the base class (vtkObject or vtkMRMLNode) if you don't know the type):
		+	static int count = 0;
		+	std::cout << "#######Object Destructed: " << this << count++ << std::endl;
		+	</li>
		+	<li>Run the application and make it crash. In the logs you shall see something like that:
		+	#######Object Destructed: 0x12345678 0
		+	#######Object Destructed: 0x12345679 1
		+	#######Object Destructed: 0x12345680 2
		+	>>>>>Object Pointer: 0x12345660
		+	>>>>>Object Pointer: 0x12345661
		+	>>>>>Object Pointer: 0x12345662
		+	#######Object Destructed: 0x12345660 3
		+	#######Object Destructed: 0x12345661 4
		+	#######Object Destructed: 0x12345662 5
		+	#######Object Destructed: 0x12345663 6
		+	>>>>>Object Pointer: 0x12345670
		+	>>>>>Object Pointer: 0x12345671
		+	>>>>>Object Pointer: 0x12345672
		+	#######Object Destructed: 0x12345660 7
		+	#######Object Destructed: 0x12345661 8
		+	#######Object Destructed: 0x12345662 9
		+	>>>>>Object Pointer: '''0x12345663'''
		+	Segfault
		+	</li>
		+	<li> Search in the logs when the pointer before crash has been deleted. Set a conditional breakpoint in the debugger:
		+	(gdb) break MyObj.cxx:103 if count == 6
		+	or
		+	(gdb) break MyObj.cxx:103
		+	(gdb) ignore 1 5
		+	or if you don't want to use a debugger, you can make it crash the 6th time:
		+	assert(count != 6)
		+	</li>
		+	<li> Analyze the backtrace to understand why the pointer has been deleted without letting know the object that tries to access it.</li>

@@ Line 62: / Line 62: @@
 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
+<li> Analyze the code to see where the leak could be</li>
 Here is a listing of the most common mistakes
 * this->MyXXX = vtkXXX::New();
@@ Line 73: / Line 73: @@
+    }
    this->MyXXX = vtkXXX::New();
 </ol>
 {{ombox
 |type=content
 |text=To reduce memory leaks, use the following tools:
-* <code>vtkNew<vtkXXX> myXXX;</code>,
+* <code>vtkNew<vtkXXX> myXXX;</code>
 * <code>vtkSmartPointer<vtkXXX> myXXX = vtkSmartPointer<vtkXXX>::New()</code>
-* and <code>vtkSmartPointer<vtkXXX> myXXX; myXXX.TakeReference(this->CreateObjAndCallerOwnsReference())</code>.
+* <code>vtkSmartPointer<vtkXXX> myXXX; myXXX.TakeReference(this->CreateObjAndCallerOwnsReference())</code>.
 }}

@@ Line 54: / Line 54: @@
   ...
 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:
+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

@@ Line 1: / Line 1: @@
 {{documentation/underconstruction}}
-* Disable plugins
+=Disable features=
 ** rename lib/Slicer-4.0/ITKFactories into lib/Slicer-4.0/ITKFactories-disabled

← Older revision		Revision as of 19:04, 20 December 2011
Line 1:		Line 1:
		+	{{documentation/underconstruction}}
		+
	* Disable plugins		* Disable plugins
	** 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