Re: hash tables and GC

[darrelj@sm.unisys.com]

   To: jeff%aiai.edinburgh.ac.uk@nss.cs.ucl.ac.uk
   From: goldman@vaxa.isi.edu
   Subject: hash tables and GC
   Cc: common-lisp@sail.stanford.edu
   Date: Thu, 21 Jul 88 09:33:27 PDT
   Sender: goldman@vaxa.isi.edu


   Do any implementations have "non-mappable" hash tables and a Garbage
   Collector that takes this into account?
   Neil


Interlisp-10 does this for all hash tables, although certain cases of
keys involving "permanent" objects like SMALLP numbers are never
automatically removed.  It also looks like pretty complicated code to
implement it.  At first blush, it seems like it would be much harder
to do in some incremental GC scheme as it requires scanning all such
hash tables before recycling objects they contain.