如何检测Free Pascal/Lazarus中的内存泄漏？

Question

在Delphi中,我通常会编写一个简单的泄漏测试,如下所示:

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.

如何检测Free Pascal/Lazarus中的内存泄漏？

Answer 1

Free Pascal也有类似的功能.在程序结束时,DumpHeap在Lazarus项目设置中调用或启用heaptrc选项.可以使用该SetHeapTraceOutput方法设置输出文件.两种方法都在单元中heaptrc,它必须是项目中的第一个(从开始捕获分配).

更多信息:

• http://www.freepascal.org/docs-html/rtl/heaptrc/usage.html
• http://www.freepascal.org/docs-html/rtl/heaptrc/environment.html

泄漏可视化:Lazarus包"LeakView"在树视图中显示堆跟踪输出文件的内容.它包含在默认安装中,并在重建IDE后可用.(尚未经过我测试)

  // 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;

输出如下:

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
  ...

(使用Free Pascal 2.6.0测试)

Answer 2

虽然mjn是完全正确的,并且他说的是首选解决方案,但在*nix上也可以使用单元"cmem"(主程序中的第一个单元)将内存管理器切换到libc的malloc,并使用其他调试工具.

如果其他选项耗尽,那么使用valgrind这样做是值得的.请注意,要使用valgrind,您需要打开-gv.