From: Eric Wong Date: 2018-01-28T10:41:49+00:00 Subject: [ruby-core:85170] Re: [Ruby trunk Feature#13618] [PATCH] auto fiber schedule for rb_wait_for_single_fd and rb_waitpid sam.saffron@gmail.com wrote: > Hmmm, what about just bringing in the IO Manager APIs > including Ruby helpers prior to re-introducing the green > threads? One big problem I notice with existing IO manager APIs (libev/libevent/EventMachine) is multi-threading was as an afterthought to them. As in, throw a lock around a single-threaded event loop and call it a day. Ruby was this way, too; but want to work towards changing that and embracing the multi-thread friendliness baked into APIs provided by kqueue and epoll. Btw, some of the discussion/planning around this started in: https://public-inbox.org/ruby-core/20170402023514.GB30476@dcvr/t/ > As it stands kqueue/epoll abstractions always require another > fat dependency and there is no official API to consume them. I don't know if exposing a new API around them is desirable. For human-friendliness, it seems desirable to keep the Ruby API synchronous even if internal bits become async. I think it's also desirable to be able to change some/most existing Thread uses to auto-Fiber/Threadlet/Thriber without having to re-design things, just changing "Thread.new" to something else. > Even just solving this problem is enough of a hornets nest > prior to introduction of other complications. > > epoll is notoriously monstrous, > http://cvs.schmorp.de/libev/ev_epoll.c?view=markup so having > an officially supported abstraction would be a great start. I disagree. IMHO, Lehman's notes and complaints against epoll are either out-of-date or his mental model went wrong somewhere. Fwiw, fs/eventpoll.c is straightforward and easy-to-understand in git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git > Wouldn't having these abstractions allow building this by hand > using existing Fiber? One question is, how painful will it be in Ruby? I've kinda soured on _nonblock APIs in Ruby over the years. For example, in https://bugs.ruby-lang.org/issues/14404 I don't think there's a non-painful Ruby way to resume a partial writev. Doable, of course, but it requires extra allocations and copies. Resuming a partial write_nonblock today without writev isn't great, either... With a synchronous interface (IO#write), dealing with partial writev in C is only a few adds/subracts; and we wont expose pointer arithmetic in Ruby :) And then there's also stuff like IO.copy_stream not having a _nonblock analogue... Unsubscribe: