Thank you for you response. Regarding the possibility if delegating CPU intensive tasks to multiple tasks: what about communication? Is there an idiomatic way to make processes communicate without blocking? There is ZeroMQ, but as far as I know it is blocking. It would be nice to develop something like Erlang/Akka using a pool of processes and cooperative multithreading locally inside each process, but I am not sure what would be the best way to keep a channel among processes
2014-10-15 14:40 GMT+02:00 Björn Lindqvist <bjou...@gmail.com>: > Hi Andrea, > > I'm not an expert, so take what's written below with a grain of > salt. It mostly comes from what I've snapped up from varius places and > reading the mailing list archive (eg > http://search.gmane.org/?query=threading&group=comp.lang.factor.general&sort=relevance). > > 2014-10-13 18:14 GMT+02:00 Andrea Ferretti <ferrettiand...@gmail.com>: >> Hi, I have read in various places, including this mailing list, that >> Factor does not currently have support for (preemptive, kernel-level) >> multithreading, and that adding support for that would require a great >> deal of changes, since the underlying VM and many core words are not >> thread-safe. > > It's true that Factor doesn't have preemptive, kernel-level threading > (I'll just write "threading" from now on when I refer to this > particular brand of threading) and that adding it would probably > require a lot of engineering and restructuring work. But if you dig > into the source, and read the previous discussions, it's clear that > adding threading was always the idea and the Factor VM has been > architected to make it simple to add in the future. > > Whether it actually is simple or not, is a different matter. But it's > much different from, say, the CPython VM which is implemented in such > a way that it would be virtually impossible to add threading. > > Most composite (non-primitive) words are thread-safe and the primitive > words are only "thread-unsafe" in that critical sections aren't > guarded by exclusion locks. > >> Can anyone expand on this? Is there some place where people have >> collected some ideas about the issues that would arise and the areas >> that need work? > > I don't think there is any particularly bloody issues. It's just a lot > of hard work. > > For example interactions between threads and gc can be very tricky. If > two threads need to allocate memory, there needs to be some > synchronization so that they don't end up pointing to the same chunk > of memory. How do you make that both fast and safe? > > What happens with a threads object references if another thread forces > a gc cycle? I guess all threads has to stop running during the gc so > that all object references can be updated. It's even more complicated > if one thread is in an ffi function which holds a pointer to a Factor > object. > > What if another thread recompiles the same word a thread is running? > >> If not, it would be nice to gather such information from people >> knowledgeable about the internals of factor, so that interested people >> could start make some contributions. >> >> I don't know if personally I would be able to contribute, but I'd love >> to if I I found something I could handle > > An alien wrapper for pthreads would be interesting. I've no idea if it > would kind of work or break Factor badly, non-the-less it would be > interesting to see. > > While we're at the subject of threading.. It's a great feature but a > language VM can do without it and still be very useful. Python, > Erlang, Node.js and Ruby all proves that. If the goal of the > concurrency is IO throughput, then cooperative threads which Factor > already has works really well. For cpu intensive tasks you can often > start multiple processes instead of threading. > > > > -- > mvh/best regards Björn Lindqvist > > ------------------------------------------------------------------------------ > Comprehensive Server Monitoring with Site24x7. > Monitor 10 servers for $9/Month. > Get alerted through email, SMS, voice calls or mobile push notifications. > Take corrective actions from your mobile device. > http://p.sf.net/sfu/Zoho > _______________________________________________ > Factor-talk mailing list > Factor-talk@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/factor-talk ------------------------------------------------------------------------------ Comprehensive Server Monitoring with Site24x7. Monitor 10 servers for $9/Month. Get alerted through email, SMS, voice calls or mobile push notifications. Take corrective actions from your mobile device. http://p.sf.net/sfu/Zoho _______________________________________________ Factor-talk mailing list Factor-talk@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/factor-talk
