#15153: GHC uses O_NONBLOCK on regular files, which has no effect, and blocks the runtime -------------------------------------+------------------------------------- Reporter: nh2 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Runtime System | Version: 8.2.2 Resolution: | Keywords: Operating System: Linux | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonmar): Yeah, this is well known. O_NONBLOCK doesn't do anything for local disk files, but it also doesn't do any harm. It's not usually a big problem except when the filesystem actually has significant latency, like with NFS or an arbitrary fuse filesystem. I think I was worried about the overhead of using safe calls here, the problem is that if you have lots of threads all reading from Handles (e.g. sockets) then if those reads are safe calls we'll get a large number of real OS threads created. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15153#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler