Comments on: Threads Happen

By: saponsky

saponsky — Wed, 30 Nov -0001 00:00:00 +0000

Hmm…very interesting. Threads issues out of the court? It’s definitely a two thumbs up.

By: mdavis0452

mdavis0452 — Wed, 30 Nov -0001 00:00:00 +0000

This is more of a question than a comment. If the Erlang threads/processes are neither operating system processes nor operating system threads, does that mean that they all live inside a single operating system processes? If so, how do you take advantage of multiple cores?

By: hilbertastronaut

hilbertastronaut — Wed, 30 Nov -0001 00:00:00 +0000

Uh, CUDA threads have nothing to do with Erlang threads, except for perhaps the name and the idea of parallelism. CUDA threads are basically an abstraction for what looks like an old-school vector processor like the Cray 1. If you think “I’m programming a much smaller, cheaper, lower-power version of the Cray 1,” you’ll probably write very efficient CUDA code. If you try to write a CUDA program with the idea of Erlang threads (message-passing with a message queue), you probably won’t get very far.

By: hilbertastronaut

hilbertastronaut — Wed, 30 Nov -0001 00:00:00 +0000

mdavis0452: think of “Erlang thread” as a job. You can multiplex N jobs onto M operating system threads in which N >= M.

By: hilbertastronaut

hilbertastronaut — Wed, 30 Nov -0001 00:00:00 +0000

mdavis0452: in my reply to your comment above, note that the runtime does the work of multiplexing jobs to threads, rather than you. So replace “[y]ou” with “the runtime job scheduler.” I’m not sure how Erlang’s runtime does it, but plenty of other systems work this way: you put jobs on a work queue, and the runtime pulls off jobs from the queue and assigns them to processors.