From Lazarus wiki

Leakview allows fast navigation through HeapTrc leak reports.



The Leakview utility is available in the IDE under View / Leaks and Traces.

Leakview reads heaptrc output. For this to work, you'll need to enable heaptrc in your code:
Never include heaptrc in your uses clause manually. This is done implicitly by the compiler when -gh is specified

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)

To get meaningful heaptrc results with descriptions to your code lines and not just assembler addresses, go to Tools/Options/Debugger/general and set a debugger.

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

  {$IFDEF debug}
  , SysUtils


  // 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


Enabling heaptrc in FPC

In FPC, you can specify -gh in your compiler options in fpc.cfg or on the commandline.
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"