In Delphi, I usually write a simple leak test like this:
program MemLeak;
{$APPTYPE CONSOLE}
uses
SysUtils;
procedure Leak;
begin
{ Put leaking code here. }
end;
begin
ReportMemoryLeaksOnShutdown:= True;
try
Leak;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
end.
How do I detect memory leaks in Free Pascal/Lazarus?
The Memory Profiler is a component in the Android Profiler that helps you identify memory leaks and memory churn that can lead to stutter, freezes, and even app crashes. It shows a realtime graph of your app's memory use and lets you capture a heap dump, force garbage collections, and track memory allocations.
Free Pascal has a similar feature. At the end of the program, call DumpHeap
, or enable the heaptrc option in the Lazarus project settings. The output file can be set with the SetHeapTraceOutput
method. Both methods are in the unit heaptrc
which must be the first in the project (to capture allocations from start).
More information:
Leak visualization: the Lazarus package "LeakView" presents the content of a heap trace output file in a tree view. It is included in the default installation and available after a rebuild of the IDE. (not yet tested by me)
// By default information is written to standard output,
// this function allows you to redirect the information to a file
SetHeapTraceOutput('heaptrace.log');
// normally the heap dump will be written automatically at the end,
// but can also be written on demand any time
DumpHeap;
The output looks like:
C:\path\to\Demo.exe
Heap dump by heaptrc unit
244 memory blocks allocated : 8305/9080
241 memory blocks freed : 8237/9000
3 unfreed memory blocks : 68
True heap size : 458752
True free heap : 458288
Should be : 458480
Call trace for block $0010CE58 size 28
$0044ACCB TIDTHREADSAFE__CREATE, line 226 of C:/path/to/indy-10.5.8.tiburon/Lib/Core/IdThreadSafe.pas
$00444245 IDTHREAD_init, line 641 of C:/path/to/indy-10.5.8.tiburon/Lib/Core/IdThread.pas
$00409D74
$0040E1A1
...
(tested with Free Pascal 2.6.0)
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