Re: [GD-Linux] Reinitializing the heap

[Steve B. <sjb...@ai...>]

"Josh Adams" wrote:

> The easiest way to get this behaviour would be to write a local
> allocator which offered those semantics.  I did this at one point
> with a head implementation that allowed watermarking.  Basically you
> could make watermarks at various times, and then free all
> still-valid allocations back to the named watermark (yeah, single
> threaded with linear process flows).

That seems dangerous beyond sanity.

If you use *any* library functions, you could end up freeing memory
it still has pointers to...your graphics library, even (in principal) the
C standard library could be using heap memory that you don't know about.

Suppose there was something like:

  void some_glibc_function ()
  {
    static char *pointer = NULL ;

    if ( pointer == NULL )
    {
      pointer = malloc ( 100 ) ;
      precompute_something () ;
    }

    ...do something using the precomputed data...
  }

...that would fail disasterously if you did what you propose.

This kind of dirty trick is common in the games console business - but
those don't have operating systems (well, not that matter) and you can
do this kind of disgusting thing and get away with it.

"Ryan C Gordon" replied:

>> That being said, someone needs to speak reasonably and say that all of
>> this is interesting, but bad, bad practice.

I just flat out don't think it'll work.

>> Shrugging your shoulders and
>> saying "hey, it's a video game after all, so who cares if it's got leaks
>> in the first place and I choose a non portable hack to fix them in the
>> second?" is not only shortsighted, but it says a lot about game coding
>> mentalities that are rampant in the industry.

Yep.  A memory leak is a **BUG** and you should determinedly seek it out
because you don't know what *all* of it's side-effects are until you've
found it.  What might have the obviously visible side effects of leaking
memory might also be corrupting something...who knows?

>> I would recommend that you attack memory problems with the correct tools:
>> dmalloc, ElectricFence, mcheck(), etc. It may save your sanity later on.

Yes.
 
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