[fpc-pascal] Problem with heaptrc

[Michael Van Canneyt]

On Sun, 9 Nov 2014, Tomas Hajny wrote:

> On 9 Nov 14, at 21:58, Xiangrong Fang wrote:
>
>
> Hi Xiangrong,
>
>> I use heap trace utility to see if there are memory leak in my program.
>> The source is here:
>>
>> https://github.com/xrfang/fpcollection/blob/aefa04f0374c94298facd8d57d4a25dafe10b753/src/demos/cache/demo.lpr
>>
>> My problem is, at the beginning of the main program, I have a costant
>> definition:
>>
>> const
>>   ITEM_COUNT = 5000000;
>> If I set ITEM_COUNT to a small value, say 50 or 5000, everything is OK, no
>> memory leak. But with the above value, it will cause HEAPTRC to fall in an
>> endless loop, generating messages like:
>>
>> Call trace for block $00007F41693AA680 size 40
>>   $000000000040071F line 29 of demo.lpr
>>   $0000000000400180
>>
>> While line 29 is this:
>>
>> 27  for i := 0 to ITEM_COUNT - 1 do begin
>> 28    for j := 0 to 4 do key[j] := $deadbeef + i + j;
>> 29    h.Add(@key, SizeOf(PtrUInt) * 5, Pointer($deadbeef + i));
>> 30  end;
>> Could anyone tell me why heaptrc will fall in an endless loop, and does my
>> program have memory leak?
>
> Are you sure that it really is endless (i.e. did you let to run for a
> sufficiently long time)? If you increase the amount of allocated
> blocks (which is what happens in case of increasing your constant),
> traversing through all the blocks (especially if they are not freed
> at the end) may indeed take fairly long time...

It is not endless. I tested, it simply takes several minutes to 
produce a stack trace for 2910911 (yes, 3 million) unfreed blocks 
of memory. The resulting heap.trc file is 300Mb.

Michael.