ghci and ghc -threaded broken with pipes & forking

[Jeremy Shaw]

Hello,

Your first problem is just a line buffering issue. You need to
explicitly set the line buffer inside the child processes:

                              redir fstdin stdInput
                              hSetBuffering stdin LineBuffering
                              redir fstdout stdOutput
                              hSetBuffering stdout LineBuffering

This is because the forked child process in not hooked up to a tty, so
GHC decides that block buffering would be a good choice.

Once you fix that you will encounter some new race condition type
bugs. These bugs will show up, even *without* the -threaded flag.

hth,
j.

At Wed, 28 Feb 2007 13:29:17 -0600,
John Goerzen wrote:
> 
> On Wed, Feb 28, 2007 at 10:40:18AM -0800, Jeremy Shaw wrote:
> > At Wed, 28 Feb 2007 11:15:04 -0600,
> > John Goerzen wrote:
> > 
> > > You can see my test case with:
> > > 
> > > darcs get '--tag=glasgow ml' http://darcs.complete.org/hsh
> > > ghc -fglasgow-exts --make -o test2 test2.hs
> > 
> > I get an erro when I use that darcs command-line, and test2.hs does
> > not appear to be in the directory afterwards. Am I doing something
> > wrong ?
> 
> Oops.  I hadn't pushed out that tag yet.  It's there now.