#1185: can't do I/O in the child of forkProcess with -threaded
----------------------------+-----------------------------------------------
Reporter: simonmar | Owner:
Type: bug | Status: new
Priority: low | Milestone: _|_
Component: Runtime System | Version: 6.6
Severity: normal | Resolution:
Keywords: | Difficulty: Easy (1 hr)
Testcase: | Architecture: Unknown
Os: Unknown |
----------------------------+-----------------------------------------------
Comment (by tibbe):
It doesn't work without `-threaded` either!
My library exports the following function:
{{{
serve :: Application -> IO ()
}}}
Where `Application` is a handler type function in the spirit of `Request
-> Response IO`.
The intended usage is for the user who wants to build a web application to
import my library and write a function e.g.
{{{
fileServer :: Application
}}}
and have a `main` that looks something like:
{{{
main = serve fileServer
}}}
The insides of the library are in principle those of HWS. `serve` reads
lots of configuration flags such as `--port` and `--daemonize` from the
command line so the user can get a functioning web application server that
he or she can deploy in production with little fuzz.
I can't see how I can support this interface and still fork in C. It seems
to me like the user needs to write the startup code in C and call `main`
from it. Not a nice user experience.
If there is a way to write a C library that forks and include it in my
library and still retain the same API I will of course use it as an
intermediate solution but I still would prefer to be able to fork
processes from inside Haskell. Forking, even in a restricted version, is
something that would be useful in Haskell. I think daemonizing processes
is a perfect example of where it's needed. I also think it is a necessary
feature for server type applications.
I understand that this might be difficult from a technical perspective,
yet it is something other languages have so it must be possible. If I
understood the issue better I could try to help come up with a solution
and also try to implement it.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1185#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler_______________________________________________
Glasgow-haskell-bugs mailing list
Glasgow-haskell-bugs@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
