Re: [MIT-Scheme-devel] DNS queries, blocking C calls, and non-file-descriptor events

[Taylor R Campbell]

   Date: Sun, 13 Aug 2006 02:35:45 -0400
   From: Chris Hanson <address@hidden>

   I am not sure why the scalability of this is important.  Are you
   generating many DNS requests in a short time?  Or are you just trying to
   build the best thing you can, and that's bothering you?

In Scheme (both Scheme48 and MIT Scheme, as well as a number of other
Scheme systems, such as Gambit), operations that `block' should really
only block one Scheme thread; that is, Scheme threads shouldn't be
able to interfere with one another.  Calling out to C means that any
Scheme interrupts are deferred until control returns from C to Scheme.
Any C call that blocks, then, isn't playing nicely: it blocks all
Scheme threads.  `Blocking' operations, then, should really be non-
blocking operations at the C level that report their progress
incrementally, and my concern is not with scalability but with playing
nicely thus in this system.