[Haskell-cafe] forkProcess, forkIO, and multithreaded runtime

Brandon Allbery allbery.b at gmail.com
Mon Oct 15 18:48:56 CEST 2012

On Mon, Oct 15, 2012 at 12:30 PM, Joey Hess <joey at kitenet.net> wrote:

>   forkProcess comes with a giant warning: since any other running threads
>   are not copied into the child process, it's easy to go wrong: e.g. by
>   accessing some shared resource that was held by another thread in the
>   parent.
> In my experience, forkProcess often behaves incomprehensibly (to me)
> with -threaded, typically resulting in a forked process hanging, and
> quite often only some small percentage of the time, which makes it
> really hard to track down and try to diagnose what thunk might not be
> getting forced until after the fork, or whatever.

The forkProcess MissingH discussion recently left me feeling like this is
going to be triggered in all cases, because it sounds like one of the
problematic threads is the I/O manager's thread?

brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix/linux, openafs, kerberos, infrastructure          http://sinenomine.net
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