Re: INFO - memory leaks

From: Daniel Koepke (dkoepke@CALIFORNIA.COM)
Date: 08/14/97

On Wed, 13 Aug 1997, George wrote:

-+For that amount of money I would adapt my buffer handling code to act as a
-+supplementary malloc() and track down the leaks in CircleMUD that way.
-+Change the CREATE() macro, make a FREE() macro, and go to town.  You could
-+track who allocated what, where, and how much.


  #define LOG_CREATE(sz)  fprintf(memlog, "%d bytes malloc'd on line %d", \
                                  sz, __LINE__);

If I remember correctly __LINE__ will work beautifully.  I think there is a
__FILE__, too? <shrug>

The problem comes when you want to FREE() something and you want to know
exactly what it is that you're free'ing.  I suppose some sort of memory
tracking system will work for this.  For instance:

  typedef struct mem_track {
     int alloc_line; /* line allocated */
     char alloc_file[128]; /* file allocated in */
     int bytes; /* bytes allocated */
  } mem_track;

Now our CREATE macro saves it all into a mem_track dynamically allocated
array and our FREE() just looks up the data to report it.  Of course, the
idea wouldn't be to turn on mem tracking and leave it on all the time.
malloc() is already slow enough without overhead needed (we're talking
about, for those that don't understand the dynamics of the mem tracking
system, calling malloc() twice for every one CREATE() call: once to actually
allocate the memory to our variable, and again to allocate memory for the
mem tracking for that variable).  So if you implement a mem tracking system,
you'll be instantly *doubling* the amount of calls to malloc(), and slowing
free() with searches.  Unless someone can come up with some better ways to
implement a mem tracking system, it would only exist to track memory when
you were aware of memory leaks; or when you got really, really bored (the
memory log would probably grow to a considerable size).

Still, for so little code and the benefits from using it every once and a
while...and the concept that in the end it serves to track down memory
leaks (although in a slightly more manual way) without $1500 software is
good enough.  A few hours reading a log file is more than acceptable
compared to shelling out money that would pay for dinner (usually pizza; I can
cook, but rarely do) for approaxiametly a third of the year...

Actually, there is a lot of software out there that costs a lot of money for
some strange reason.  For instance, 3D Modelers and Renderers.  Even the
ones that suck in power and ease of use cost $400...:P  And the good stuff
can range from $4000 to $9000 and require insane computer equipment...  Why
can't good things come with small price tags instead of small packages?

-+Sounds like a good idea actually. I need to stop having those, it just
-+gives me more things to do.

Most of my ingenious ideas come to me a month after some guy just got a
patent and made $15 million... :)  Really sucks to come upon a brilliant
idea all by yourself to find out some big corporation's R&D team came upon
it and the patent is pending.  If my ideas would just come a month faster
I'd be a rich man...

-+So who wants to be the first to pay me $1,500 for it? ;)

<gasp> You're suggesting that some people *won't* pay $1500 for it?  Anything
to avoid reinventing the wheel!

Speaking of money, maybe I'll start selling .sig lines, because you gotta'
admit I've come up with some pretty groovy ones ("Forgive me father, for I am
sin" is still a favorite, although the Ebonics version ["Fo'give me fadda'
'cuz I be sin"] evoked some laughs, too :).

Daniel Koepke -:- -:-  [Shadowlord/Nether]
Perversion test: "There she blows!" conjures what image?

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