[GHC] #13554: Allow the user to provide a C function that is called on each thread the RTS creates before running any Haskell code

[GHC]

#13554: Allow the user to provide a C function that is called on each thread the
RTS creates before running any Haskell code
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        Reporter:  dobenour          |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Runtime System    |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 There is a bit of a tricky interface question here. It seems to me like
 allowing only one callback is insufficient. Afterall, what when you want
 to use both MySQL and libcurl? It seems that you really need the ability
 to register multiple callbacks for this to be robust.

 However, there is also the question of what the precise semantics of this
 callback are. Should it get called on threads which are pre-existing at
 time of callback registration? Does the callback get called in the context
 of each thread, or merely with its, e.g., `pid`?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13554#comment:2>
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