Re: Ada GC (was about Java VM)

dewar@cs.nyu.edu (Robert Dewar) wrote:
> "As a non-expert in hard real-time systems, the last sentence strikes
> me as very strange. There are well-known GC algorithms that guarantee
> hard real-time bounds, as well as reasonable (linear) space bounds.
>
> During the design of Ada 95, it became abundantly clear that this view
> is NOT shared by most experienced practioners in the real time field.


hbaker@netcom.com (Henry Baker) writes:
>Let's see, RT GC has now been around for almost 20 years (Wadler's
>CACM paper was published in Sept. 1976 and my MIT AI working paper was
>published in 1977 and received wide distribution). There have been


  I'm just a lowly grunt who develops & maintains embedded real-time
app's in Ada, but ...


It is real tough to sell runtime GC in safety-critical app's, period!
The perception amongst the customers (& I agree with them) is that if
you can't model the system well enough to build it without!!! GC, then
you don't understand the system well enough to build it at all!


You can take all kinds of shortcuts if you're building a spreadsheet
program or a network-server or some such where if the system crashes
once in awhile, you just reboot or whatever and tell the customers
"tough!" ... but that approach literally does not "fly" when airplane
control-movements & weapon-releases and such hang in the balance.


I program a little in c & c++, and it's real nice to be able to have
the RTS manage memory ... but if ever there came along a
safety-critical customer who allowed an off-the-shelf RTS to manage
memory, I'd "launch" off to another job in my reliable little GC-free
Ada-powered jet!


                                                                                                    imho
--

Return to the comp.compilers page.
Search the comp.compilers archives again.