Implicit garbage collection in Ada systems

[saharbaugh%roo.dnet@WINNIE.BERKELEY.EDU]

On 8 Jan 91 Robert Firth writes, in part:
-For a program to use it, certain minor conditions have to be met, but
-the bottom line is that it allows a transaction-processing system to
-run forever (ie without storage fragmentation or other entropic
-degradation), and to do so with bounded performance and with bounded
-storage requirements.

     Thank you Robert for the succinct and eloquent summary.

On 8 Jan 91 Jerry Callen writes:

-Well, let's not be so coy, fellas! :-) It sounds as if a patent
-application or other obstacle is preventing you from saying more,
-but The Perfect Heap Manager is kind of a holy grail, and _I_ would
-love to know more. 

-In particular, just WHAT restrictions have to be placed on the
-application? Hey, I can prevent fragmentation, too, if all the
-allocated objects are the same size. :-)

--- Jerry "you've piqued my curiousity" Callen
-   jcallen@encore.com

    Truly, I am not trying to be coy, just cautious.  You guessed it, there is 
a patent application involved.  For now we are having people sign a non-
disclosure form so that we have some form of containment.

    The HeapGuard scheme is based on two premises, 1) The heap size is 
derated by a certain amount and 2) a certain allocation scheme is used.  If 
the user asks for a heap of size N then HeapGuard reserves a heap of size 
larger than N and as long as the user never tries to use more than a total of 
N at any time the user may allocate and deallocate objects of size 1..N and 
never experience heap overflow or garbage collection.  

     The HeapGuard scheme can be implemented totally in software, which 
we have done.  The amount of unused memory can be greatly reduced 
with the support of special hardware memory addressing circuits, 
especially when the heap space can be handled in blocks (say 16 Bytes).  
We have had such a board designed and built and it is running.

     The HeapGuard algorithm was verified by simulation and Larry Koos 
of Koos Technical Services, who designed the board circuits, developed a 
"proof".

     So please let me know if you want to apply HeapGuard or if you 
would like to work on verifying the proof.  


Sam Harbaugh
Integrated Software, Inc.
1945 Palm Bay Rd #7
Palm Bay, FL 32905   (407) 984-1986  fax (407) 951-4291
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