[fpc-pascal] Heap, Stack, HeapTrc and threads

[Jonas Maebe]

On 24 Nov 2011, at 16:28, <andrew.bennett at ns.sympatico.ca> <andrew.bennett at ns.sympatico.ca 
 > wrote:

> At no point did the heap status reveal the growing amount of space  
> tied up: the
> only odd thing was that TotalAllocated sometimes came back negative in
> the threads as the program approached the point of running out of  
> memory
> (at the 2GB addressing limit; the machine has 6GB).

The fact that the heap status counters are unreliable since the latest  
rewrite of the heap manager is a known problem:
* http://bugs.freepascal.org/view.php?id=15805
* http://bugs.freepascal.org/view.php?id=14315
* http://bugs.freepascal.org/view.php?id=15763

> In the course of eliminating the workspace originally allocated as  
> dynamic
> arrays, I discovered 2 unmatched SetLength procedures. As I mentioned
> above, these were never reported by HeapTrc.

That's because they don't cause memory leaks (except in case of direct  
pointer manipulations, but in that case crashes are more likely than  
memory leaks). Memory management for dynamic arrays and ansi/wide/ 
unicodestrings is automatic via (hidden) reference counting.

I've never seen any reports of heaptrc failing to report memory leaks.  
Most likely, your problems stem from internal heap fragmentation  
rather than from memory leaks. Such problems can usually be solved by  
using the "cmem" unit, which falls back to the default C library's  
memory manager (FPC's heap manager is generally faster, except in  
cases of lots of fragmentation).


Jonas