Date: Wed, 22 Apr 1992 03:55 EDT
From: Fred Tusveld <·······@ictser.uucp>
Hello,
Recently, I was told by someone from Gensym that Lisp's Garbace
Collection problems was the main reason for them to start delivering in
C. I was surprised to hear this, as I thought Lisp there was a large
number of process control applications written in Lisp. I do recall
other examples of people denouncing Lisp for process control
applications for the same reason. It made me wonder how the GC problem
was dealt with in earlier implementations of Gensym, Mercury and similar
Lisp process control implementations.
It was my understanding that GENSYM still developed in Lisp, but did all
their storage allocation and deallocation using explicit mechanisms,
rather than relying on the automatic storage management of the
underlying Lisp. [This could be a mis-impression on my part.]
Symbolics has developed a derivitive version of it's Genera system for
real-time process-control applications that guarantees GC will not
impose a latency of more than 30ms on application processes, and where
average measured latencies are more on the order of 1-2ms. The system
is being successfully used in a prototype application by the customer
for whom it was developed. For this particular application, automatic
storage management was deemed a required feature, because it prevents a
large class of bugs from occuring and simplifies the development and
on-line evolution of the control program.