[GHC] #1185: can't do I/O in the child of forkProcess with -threaded

[GHC]

#1185: can't do I/O in the child of forkProcess with -threaded
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 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         |  
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Comment (by igloo):

 Replying to [comment:3 simonmar]:
 > I'd advise against this.  forking is a total pain in a multi-threaded
 program, and I really don't want to commit to making it work for anything
 other than simple fork/exec type usage (and possibly not even that - doing
 the fork/exec in C is better).
 >
 > Do you really need both -threaded and `forkProcess`?  Can you fork in C
 ''before'' starting up the Haskell runtime?

 I really think we ought to be able to say something like

 {{{
 main = do args <- getArgs
           configFile <- readConfigFile
           let config = args .+. configFile
           if runAsDaemon config
               then daemonise realMain
               else realMain
 }}}

 (where `daemonise` does the standard double-forking thing) without having
 to resort to writing C code. Using `forkIO`, `forkOS` etc before
 `daemonise` wouldn't necessarily have to be supported.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1185#comment:5>
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