Hi all, (There's a TL;DR at the bottom---I'd like to contribute code to help libuv work after a fork() on unix.)
I'm one of the gevent maintainers. gevent is a fairly popular[1] Python library for asynchronous event-driven programming (primarily networking, but other things as well). Currently gevent is based on libev and supports both unix and Windows while implementing an API compatible with the Python standard library. There's been interest expressed by our community in moving off of libev and onto libuv, primarily for improved Windows support. So recently I've implemented a prototype backend for gevent using libuv [4]. Let me start by saying how much of a joy the libuv API is to work with. It's clean and consistent, and the source code is easy to read. Not all event loops are like that. I really appreciate the work that the maintainers and contributors have put into libuv. I've been able to get gevent's test suite to pass with libuv on OS X and Linux, with the exception of those tests that involve forking but *not* execing. Being able to continue to run Python code in a forked child process is a crucial part of the way many Python programs on unix are written, including not just network servers like gunicorn but those that use the standard library 'multiprocessing' feature to improve concurrency. Currently after a fork, libuv either is in an interesting state where things may or may not function (three different results in gevent's test suite on three different linux distros) or it simply aborts the whole process (kqueue, aix and sunos-based systems). I've been unable to find a reliable workaround to this. Unless gevent can survive a fork, I won't be able to base it on libuv. As a gevent maintainer, that makes be sad because libuv is so nice to work with (and I'm really not interested in maintaining both a libev and libuv backend). TL;DR: I'm willing to write code to help libuv survive a fork() (I can easily test on OS X and Linux). But before I start, would the maintainers be willing to accept such a patch? I realize that libuv strives to be fully cross-platform, and I also realize that similar issues have been brought up before (e.g., [2], [3]), but I didn't find anywhere that specifically said "no way." There are multiple approaches that could work for gevent, everything from a libev-style 'uv_loop_fork()' call where all the watchers survive (obviously ideal from my point of view, especially if fork watchers got added too :), to simply terminating the loop in the child and letting gevent create a new loop and watchers. If this is something the maintainers are interested in, I look forward to working together to find the best approach. (And if this is best discussed in another venue like a github issue or IRC I'm happy to continue there.) Thanks, Jason [1] Approximately 444,000 downloads last month (https://pypi.python.org/pypi/gevent) [2] https://github.com/joyent/libuv/pull/1136 [3] https://github.com/joyent/libuv/issues/1405 [4] https://github.com/gevent/gevent/issues/790 -- You received this message because you are subscribed to the Google Groups "libuv" group. To unsubscribe from this group and stop receiving emails from it, send an email to libuv+unsubscr...@googlegroups.com. To post to this group, send email to libuv@googlegroups.com. Visit this group at https://groups.google.com/group/libuv. For more options, visit https://groups.google.com/d/optout.
