[GHC] #3210: Allow programs to change the number of capabilities

[GHC]

#3210: Allow programs to change the number of capabilities
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Reporter:  NeilMitchell      |          Owner:                  
    Type:  feature request   |         Status:  new             
Priority:  normal            |      Component:  Compiler        
 Version:  6.10.2            |       Severity:  minor           
Keywords:                    |       Testcase:                  
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
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 It would be useful for a program to choose the number of capabilities it
 has, perhaps in response to a flag. i.e. I'd like users to type {{{hlint
 -j3}}} rather than {{{hlint +RTS -N3}}}.

 To support this change one option would be to allow increasing the number
 of capabilities after a program has started. Another option would be to
 provide a primitive {{{restartWithCapabilities :: Int ->  IO ()}}} that
 aborted the program, and restarted {{{main}}} but with the required
 settings.

 Using RTS flags is unsuitable for people who use Haskell programs but
 aren't really Haskell developers. As more programs go multi-core, this
 feature will probably become more desirable. However, it's not too
 important and can always be solved by a little shell script.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3210>
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