Search code examples
delphifastmm

FastMM does not show leaks even if Inc file is properly set

An old project landed in my hands. It has 130000 lines of really bad code (no try/finally all exceptions swallowed, thousands of global variables). I expect thousands of memory leaks. However, FastMM4 shows nothing on shutdown. No message box, no txt log file.

I use the same FastMM settings (inc) for all other projects, it works. So, I am not suggesting FastMM (or its settings) is broken. I think just can't handle this impressive amount of leaks. A friend of mine told me that on a large project also with many leaks, it needed 5-10 minutes until FastMM generated the txt log.

Verifications:

  • FastMM is declared on the first line in DPR.
  • I manually created a line of code to generate a leak.
  • EnableMemoryLeakReporting is defined (see listing below)
  • I am in debug mode (Map file generation is set to "Detailed")

Any tips on how to get the log?

{$define UseCustomFixedSizeMoveRoutines}
{$define UseCustomVariableSizeMoveRoutines}
{$define NoDebugInfo}
{$define ASMVersion}
{$define CheckHeapForCorruption}
{$define DetectMMOperationsAfterUninstall}
{$define FullDebugMode}

  {$define RawStackTraces}
  {$define LogErrorsToFile}
  {$define LogMemoryLeakDetailToFile}
  {$define ClearLogFileOnStartup}
  {$define LoadDebugDLLDynamically}
  {$define AlwaysAllocateTopDown}
  {$define SuppressFreeMemErrorsInsideException}

{$define EnableMemoryLeakReporting}
  {$define HideExpectedLeaksRegisteredByPointer}
  {$define RequireDebuggerPresenceForLeakReporting}
  {$define EnableMemoryLeakReportingUsesQualifiedClassName}
{$define EnableMMX}
  {$define ForceMMX}

enter image description here

enter image description here

Solution

  • I have found the reason: The person who wrote the code uses KillTask to terminate the program (followed by Application.Terminate).
    I removed that code. Now FastMM generates the log file which is 12MB! I have to fix them. Lucky me!

    Personal thoughts: When I got the solution, I was sad, and I thought maybe this was not supposed to be a post for StackOverflow. On a second thought, it is fine. We learned something today: how not to write programs :)
    Also, we learned that there are myriad of magic ways in which a mad programmer can break a program and we will spend days to figure our his mad-ways.

    (In my language we have a saying: "When a mad-man throws a rock in a lake, 10 smart people cannot retrieve it", which means that it is easy to do something stupid, it is difficult to fix it.)