Re: [Chicken-users] Anyone up for porting Termite to Chicken?
It appears that I was wrong about not being able to start MPI processes dynamically. The MPI-2 standard does include a procedure MPI_Comm_spawn which can be used to create MPI processes from a master process. In fact, one of the main motivations for MPI-2 was to break free from the static process model. I have added a binding for MPI_Comm_spawn to the mpi egg, and it appears to work as advertised with Open MPI under Linux. My impression of the Erlang process model is also based on the documentation. Both systems seem to follow a very similar approach in that the processes are completely isolated from one another, and there is a system-wide barrier synchronization facility. This is what makes implementing concurrent systems in Erlang and MPI so easy. The real trouble with concurrent systems starts when you share memory and both Erlang and MPI avoid this zealously. But I will be interested to hear about other aspects of Erlang and Termite that are lacking in Chicken MPI. -Ivan Mark Fredrickson <[EMAIL PROTECTED]> writes: > An Erlang "process" is really a green thread, not dissimilar to > Chicken's continuation based threads. Erlang processes run inside of a > virtual machine, which is the equivalent of the Chicken run-time. At > least on paper (which is as far as my knowledge extends) the Erlang > and Scheme + MPI models are fairly similar. > > I do believe that one can start a new Erlang VM and add it to the > cloud at any time, but I get the impression this is actually rare. > With n cores, why not just start a VM on each core to begin with? The > Erlang designers are extremely paranoid about the VM's stability (e.g. > I understand a large portion of IO is done over pipes so that if the > IO process crashes, the VM is safe), so restarts of VMs tend to be > few. This is probably one area that Chicken would not fair as well. In > Erlang, if one "process" (thread really) has a problem it crashes (by > design) and everyone else is fine. A Chickeny Termite would probably > need to expend some effort to match this. Though I think it certainly > could be done. ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Anyone up for porting Termite to Chicken?
On Wed, May 21, 2008 at 9:39 AM, Mark Fredrickson <[EMAIL PROTECTED]> wrote: > I do believe that one can start a new Erlang VM and add it to the cloud at > any time, but I get the impression this is actually rare. With n cores, why > not just start a VM on each core to begin with? A year or two ago, the Erlang VM gained SMP support, so while it runs green threads, they can be executed in parallel. I believe this is called M:N threading (running M green threads on N native ones). Prior to this, I suspect one-vm-per-core was an Erlang idiom. Graham ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Anyone up for porting Termite to Chicken?
On May 20, 2008, at 8:04 PM, Ivan Raikov wrote: Answers embedded below: Alaric Snell-Pym <[EMAIL PROTECTED]> writes: Well, as far as I can tell, MPI seems to have a fairly static view of the world as having a fixed number of processes in it upon startup, so the following (in Erlang) comes to mind: http://www.erlang.org/doc/reference_manual/processes.html#10.2 Which, basically, creates a new process and returns its PID, which is then usable as the destination for a message send. Ok, you cannot do this with MPI as far as I know. An Erlang "process" is really a green thread, not dissimilar to Chicken's continuation based threads. Erlang processes run inside of a virtual machine, which is the equivalent of the Chicken run-time. At least on paper (which is as far as my knowledge extends) the Erlang and Scheme + MPI models are fairly similar. I do believe that one can start a new Erlang VM and add it to the cloud at any time, but I get the impression this is actually rare. With n cores, why not just start a VM on each core to begin with? The Erlang designers are extremely paranoid about the VM's stability (e.g. I understand a large portion of IO is done over pipes so that if the IO process crashes, the VM is safe), so restarts of VMs tend to be few. This is probably one area that Chicken would not fair as well. In Erlang, if one "process" (thread really) has a problem it crashes (by design) and everyone else is fine. A Chickeny Termite would probably need to expend some effort to match this. Though I think it certainly could be done. Cheers, -Mark ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
