network programming with GHC 7

Bryan O'Sullivan bos at
Thu Oct 28 12:12:55 EDT 2010

On Thu, Oct 28, 2010 at 2:16 AM, Kazu Yamamoto <kazu at> wrote:

> When I compiled a network server with GHC 7 without the "-threaded"
> option and ran it, I got the following error.
>        file descriptor 5496824 out of range for select (0--1024).
> I have read the paper "Scalable Event Handling for GHC" and understand
> that this new IO manger assumes the "-threaded" option.

The unthreaded runtime has a completely different I/O manager from the
threaded one. We didn't touch the unthreaded runtime. Does your app work
under earlier versions of GHC without -threaded?

> Does this mean that we need the "-threaded" option to GHC 7 for
> networking programming and GHC 7 does not maintain backward
> compatibility?

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