[gclist] ref-counting performance cost

Nick Barnes Nick.Barnes@pobox.com
Sat, 02 Sep 2000 14:07:47 +0100

At 2000-09-01 22:58:57+0000, Manoj Plakal writes:

>       Would it be correct to say that RC is the most widely used
>       "automatic" memory management technique outside academia?

Yes and no.  There are probably more instances of reference counters
than marking collectors, but this is because reference counting is
used for OS internals in a zillion computers and embedded devices all
around the world.  I wouldn't be surprised if my cheap desktop printer
has a reference counter inside it, whereas real garbage collection
will probably only be found in more costly printers (e.g. anything
which supports PostScript Level II).  I would be very surprised if
this iMac doesn't have five or more reference counters in it, but it
may only have one or two real garbage collectors (e.g. in the JVM).q

>       Are there examples of important and widely-used commercial
>       applications that use mark-sweep/copying collectors?

It all depends on what you mean by "widely-used", but AutoCAD springs
immediately to mind.  There are many other applications with embedded
interpreters for LISP or another declarative language which required
real GC.  And there are certainly large numbers of commercial
applications written in such languages.  Historically this was
especially true of LISP; today it is especially true of Java.

Nick B

FreeBSD 2.2.8-RELEASE: up 6 days, 17:06
last reboot Sat Aug 26 21:11 (lightning strike)