Re: [Haskell-cafe] How can I avoid buffered reads?

On Thu, Dec 6, 2012 at 3:24 PM, Tristan Seligmann wrote:

On 29 Nov 2012 12:27 PM, "Leon Smith" wrote: System.Posix.IO and Foreign. This appears to work, but for better or worse, it is using blocking calls to the "read" system call and is not integrated with GHC's IO manager. This shouldn't be an issue for my purposes, but I suppose it's worth pointing out.

Reading from an fd corresponding to an actual file is always blocking. select() will always indicate that the fd is ready for reading and writing, and I think epoll() will refuse to operate on the fd at all.

This; it's a longstanding gripe among those of us who use network filesystems heavily, since it's entirely possible those reads *will* block... but the usual architecture of Unix-like kernel filesystem code doesn't provide any way to see it or do anything about it. (This is also why NFS "hard" mounts are annoying and "soft" mounts are terrible fragile hacks. It's no better with any other network filesystem; they just default to the "hard" behavior because the "soft" hack, when even possible, is even worse for most of them.) -- brandon s allbery kf8nh sine nomine associates allbery.b@gmail.com ballbery@sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net