leakview

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Leakview ('[View|Leaks and Traces]') allows fast navigation trough HeapTrc leak reports.

leakview.png

Usage

Leakview reads heaptrc output. For this to work, you'll need to enable heaptrc in your code:

Enabling heaptrc in Lazarus

To enable this in your Lazarus project: go to Project Options/Linking and in the Debugging section enable Use Heaptrc unit (check for mem-leaks) (-gh)

You can then let the program log the output of the heaptrc unit to a file. Add the following code fragments in your .lpr, at the beginning of your code to redirect the heaptrc output to file:

  {$DEFINE debug}     // do this here or you can define a -dDEBUG in Project Options/Other/Custom Options, i.e. in a build mode so you can set up a Debug with leakview and a Default build mode without it

uses
  ...
  {$IFDEF debug}
  , SysUtils
  {$ENDIF}

...

begin
  {$IFDEF DEBUG} 
  // Assuming your build mode sets -dDEBUG in Project Options/Other when defining -gh
  // This avoids interference when running a production/default build without -gh

  // Set up -gh output for the Leakview package:
  if FileExists('heap.trc') then
    DeleteFile('heap.trc');
  SetHeapTraceOutput('heap.trc');
  {$ENDIF DEBUG}

  ...
end.

Irrelevant dialog box section

Light bulb  Note: You should not see the dialog boxes below if you have properly configured heaptrc like in the example above.

On Unix systems the leakview results are stored in a file the path of which is specified. Windows displays dialog boxes like the following example:


Standard output of heaptrc on Windows (despite of the title there is no error in the application)

Alternatively, for any non-trivial leak you may see a seemingly endless series of dialog boxes like those below - which makes debugging almost impossible.

Warning-icon.png

Warning: Why does this section on dialog boxes keep coming back? Hopefully the info below demonstrates that not configuring heaptrc on Windows is not a smart thing to do. If wiki editors disagree, please clean up article as you see fit.

Standard output of heaptrc on Windows (truncated at 5 dialog boxes as you probably get the point by then

Standard output of heaptrc on Windows (truncated at 5 dialog boxes as you probably get the point by then

Standard output of heaptrc on Windows (truncated at 5 dialog boxes as you probably get the point by then

Standard output of heaptrc on Windows (truncated at 5 dialog boxes as you probably get the point by then

Standard output of heaptrc on Windows (truncated at 5 dialog boxes as you probably get the point by then

Enabling heaptrc in FPC

In FPC, you can specify -gh in your compiler options. Never include the heaptrc unit in your uses clause manually. You can test if your binary is compiled with heaptrace by:

{$if Declared(UseHeapTrace)}...{$ifend}

Then redirect the heaptrc output to file (instead of standard output). You can use similar code to the Lazarus code or alternatively, set the environment variable, e.g. on *nix:

export HEAPTRC="log=heap.trc"

or Windows:

set HEAPTRC="log=heap.trc"