Re: [MIT-Scheme-devel] Cleaning weak hash tables in secondary GC daemon?

[Taylor R Campbell]

   Date: Wed, 14 Sep 2011 19:17:09 +0100
   From: Alexey Radul <address@hidden>

   Is there any reason why there is no secondary GC daemon that runs
   hash-table/clean! on all weak hash tables?  Are there any issues I
   should be aware of before installing one to clean some select weak
   hash tables that are present in my program?

It's not a good idea to call HASH-TABLE/CLEAN! in a GC daemon because
it may rehash the table in case it has shrunk.  But just cleaning the
table and not shrinking & rehashing it may leave it in a bogus state.
Working around this probably requires implementing a deferred-rehash
mechanism.  Not conceptually difficult, but it would take a bit of
work.