"zuzu" <sean.zuzu / gmail.com> schrieb im Newsbeitrag
news:a988e9f604070901005e1b428e / mail.gmail.com...
> On Fri, 9 Jul 2004 16:27:32 +0900, Robert Klemme <bob.news / gmx.net>
wrote:
> >
> > "zuzu" <sean.zuzu / gmail.com> schrieb im Newsbeitrag
> > news:a988e9f6040709000063dba1f5 / mail.gmail.com...
> > > On Fri, 9 Jul 2004 14:57:33 +0900, Robert Klemme <bob.news / gmx.net>
> > wrote:
> > > >
> > > > "zuzu" <sean.zuzu / gmail.com> schrieb im Newsbeitrag
> > > > news:a988e9f60407081357560a9592 / mail.gmail.com...
> > > >
> > > > > On Thu, 8 Jul 2004 19:27:41 +0900, Robert Klemme
<bob.news / gmx.net>
> > wrote:
> > > >
> > > > > one important aspect i have neglected to emphasize is the nature
of
> > > > > flow-based (aka "agent") programming style in ruby.  see
> > > > > http://www.jpaulmorrison.com/fbp/index.shtml
> > > >
> > > > "Flow based" seems to me just another name for "event driven" from
> > what I
> > > > read so far.  It's a bit graph theory, a bit Petri Nets, a bit
> > concurrency
> > > > theory - not nearly as sensational as the author tries to make us
> > think.
> > >
> > > word on graph & concurrency theory, reading up on petri nets now
> > > (wikipedia)...  (also reminds me to finish reading 'Linked' by ALB.)
> >
> > :-))
> >
> > > perhaps there's something better for me to read up on event driven
> > > programming besides [http://c2.com/cgi/wiki?EventDrivenProgramming],
> > > but it sounds much earlier in the evolution of an idea.
> >
> > I think in the telco world this is quite ubiquituous.  SDL is used to
> > design such scenarions (communicating proceses) and SDL is widely used
in
> > that area AFAIK.
>
> word, i think i've heard that before.  if i think of the specific
> context i'll post it.
>
> > > > > # how can ruby utilize the 4 CPU cores for this massively
parallel
> > > > > bounded-buffer data-flow as a single unix process with only
internal
> > > > > threading?
> > > >
> > > > So basically what you want is, that Ruby makes use of native
threads.
> > I
> > > > guess it would be much easier to implement a Ruby interpreter that
> > uses
> > > > native threads than to make a Mach microkernel server.  And it's
more
> > > > portable (i.e. POSIX threads).  This sounds a bit like the wrong
> > hammer to
> > > > your problem.  But then again, I'm not a microkernel expert.
> > >
> > > maybe i'm nitpicking, but i feel a problem exists that processes,
not
> > > threads, are necessary.  when the parent process dies (perhaps
because
> > > of a bad thread), all of its threads go with it.  this is a problem
> > > when one small error causes my entire application to crash.  (one
> > > small error in one object in my web browser should not lose me all
of
> > > my "unsaved" rendered pages and URL information with it.  just that
> > > one faulty object should die and get respawned.)  maintaining my
human
> > > productivity with persistent objects is more valuable than the
> > > footprint of many processes.  O(1) schedulers make "too many
> > > processes" a moot point in a cheap hardware world anyway, methinks.
> >
> > Well, normally a dying Ruby thread does not kill the whole process.
> > Whether multiple processes or threads is not the major point.  The
major
> > point is that you need concurrency for flow based programs to happen,
not
> > a kernel integration.  The kernel integration might be a means but it
> > looks inappropriate to me.
>
> but processes never corrupt/crash other processes, except in the event
> of a kernel panic, correct?  however much debate exists over the
> safety of threads.  though pan-unix compatability would be much more
> popular than a mach kernel implementation (which basically means apple
> xnu and gnu/hurd).
>
> http://c2.com/cgi/wiki?ThreadsConsideredHarmful
>
> " Some tasks may be truly independent; having independent simultaneous
> flows of control is useful.
>     * But: Separate processes may be a better solution.
>           o On some OS's (ie Windows) that is much more expensive than
> separate threads (on Unix derivatives, separate processes are much
> cheaper)"
>
> and according to john carmack writing quake 3:
> #  avoid threads if possible
> # if you have to have threads, then have only one per CPU
> # avoid threads if possible
> # share as little data as possible between threads
> # are you sure a separate process with shared memory or other IPC
wouldn't do?
>
> i think inter-process communication (IPC) is more preferable as well.
> (though i'm open to discussing the semantical differences.)
>
> i believe i am asking this same question:
> "I would reply to GlenStampoultzis with a question of my own: why use
> threads at all if you isolate the parts of your program properly?
> Processes with message passing could do just as well, no?  --
> PierrePhaneuf"

The usual tradeoff is, that threads are cheaper (some OS call them Leight
Weight Processes) because there's less overhead involved during task
switches.  Threads automatically share all their memory while for
processes you have to implement that using the operating system's
mechanisms for shared mem - or message passing.  Whatever.

When I said "The major point is that you need concurrency for flow based
programs to happen, not a kernel integration." I wanted to make clear that
you don't need kernel integration to make flow base software happen in
Ruby in the first place.  It's the concurrency and especially utilization
of several CPU's which can't happen with the current interpreter.  (Hence
Ruby2 - AFAIK native threads is a planned feature there.)

> > > > > one possible solution i thought of is to port the ruby
interpreter
> > as
> > > > > a Mach microkernel server, sitting beside the bsd "personality"
> > > > > server.  each object would be a Mach task while each function
would
> > be
> > > > > a Mach thread, and objects would communicate via Mach
inter-process
> > > > > communication (IPC).  networking and filesystems can also be
> > accessed
> > > > > through Mach.
> > > >
> > > > IMHO making each object a mach task would be overkill.  You
probably
> > meant
> > > > each *component* (i.e. independent self contained processing unit
as
> > > > described by Paul Morrison) should be a mach task.
> > >
> > > you do not think that paul's "components" essentially map directly
to
> > > ruby "objects"?
> >
> > Exactly.
>
> hehe, um, because...?

It doesn't make sense.  Not every instance does processing, just like the
bottles are shoved around only but without any activity on their own.  You
don't want a String to have a thread of control.  What should it do?

    robert