Threads?

[Per Bothner]

Chris Dean wrote:
> I'm a little confused about the state of multi-thread support in Kawa.
> 
> The fluid-let docs say: "The temporary bindings are only visible in the
> current thread, and its descendent threads".  And the Threads docs say:
> "So far, little or no effort has been made into making Kawa thread-safe.
> There are no per-thread bindings, and the current input and output parts
> are global.  That needs to change".
> 
> Those sound contradictory to me.  Is the Threads doc still correct?

No.  fluid-let bindings are per-thread.  They get inherited
by child threads.  (There is a related discussion of "parameters"
at http://srfi.schemers.org/srfi-39/ when whether threads should
inherit binding state.  That may effect fluid-let.)

The current input and output ports are not global.  They are
per-Future.  Note than parts of the Kawa design require you to use
Futures to manage thread-specific state.  This design pre-dates
the newer per-thread CallContext, and perhaps should be re-done.

Creating and modifying Bindings in Environments is probably
not thread-safe, and this may be a problem.  Note that
undefined identifiers may involve creating Bindings at
class loading time.  I'll have to think about how to fix this.
(Anyway, I'm not satisfied with how Environments work, and
how they relate to "namespaces" and "packages".)
-- 
	--Per Bothner
per@bothner.com   http://www.bothner.com/per/