Thread: VirtualAlloc and ReportMemoryLeaksOnShutdown

just a random question, can anyone explain to me why VirtualAlloc is not causing memory leaks? (GetMem & GetMemory do cause them)

Code:

program Project1;

{$APPTYPE CONSOLE}

uses
  Windows;
Var
  Mem : Pointer;
begin
  ReportMemoryLeaksOnShutdown := True;
  //GetMem(Mem, 256);//<-creates memory leak
  //Mem := GetMemory(256);//<-creates memory leak
  Mem := VirtualAlloc(Nil, 256, MEM_RESERVE, PAGE_READWRITE);//<- no leak reported 
end.

http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx

MEM_RESERVE
0x2000
Reserves a range of the process's virtual address space without allocating any actual physical storage in memory or in the paging file on disk.

if add "MEM_COMMIT" flag, it will cause leak

if add "MEM_COMMIT" flag, it will cause leak

really? then... does anyone can explain to me how the hell a WinAPI function would report a memory leak to a Delphi runtime? and by the way reserving a virtual memory page and not freeing it is actually a leak too...

just a random question, can anyone explain to me why VirtualAlloc is not causing memory leaks?

because you don't understand what you are doing... again VirtualAlloc is a WinAPI function that is why...

ADD: just to make it clear... detecting memory leaks are not operating system feature, it's a part of language features... just like a garbage collection is a part of runtime in D, Go or Python languages for example... GetMemory function is a part of Delphi runtime (just like operator new are part of C++ and D runtime for example), it is not a operating system function... the code of GetMemory function provides additional code for leaks detection and calls operating system function to allocate memory, if we are talking about windows I bet it would be HeapAlloc (kernel32.dll) or malloc (msvcrt.dll), if we are talking about linux I bet it would be malloc (libc.so)...

@bigrig; no.
@LeFF; thanks that makes perfect sense, but what I did is causing a leak, so I think it's weird that it's not being reported. :/

[edit]
just in case anyone is still confused. there is a leak, but apparently ReportMemoryLeaksOnShutdown only reports leaks reported by the Delphi wrapper, so it doesn't report on winapi :/

@LeFF; Cracksman could have thought that embarcadero implented a feature that monitors all created memory and they were keeping track of all allocated memory. Unfortunatly, they do not do this and you will have to write a wrapper yourself if you want to deal with this sort of memory leaks.