[GHC] #9003: GHC eventlog: thread stop status codes modified (breaking ghc-events, threadscope, edentv)

[GHC]

#9003: GHC eventlog: thread stop status codes modified (breaking ghc-events,
threadscope, edentv)
-------------------------------+-------------------------------------------
        Reporter:  jberthold   |            Owner:  simonmar
            Type:  bug         |           Status:  new
        Priority:  normal      |        Milestone:  7.8.3
       Component:  Runtime     |          Version:  7.8.2
  System                       |         Keywords:
      Resolution:              |     Architecture:  Unknown/Multiple
Operating System:              |       Difficulty:  Easy (less than 1 hour)
  Unknown/Multiple             |       Blocked By:
 Type of failure:  Other       |  Related Tickets:
       Test Case:              |
        Blocking:              |
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Comment (by simonmar):

 I agree with Edward.  The fact that the thread statuses are written
 verbatim into the event log is the real bug here, because it ties the
 thread status values to the event log format, whereas they ought to be an
 internal implementation detail.  We only did it this way in the first
 place because we are lazy (that's the royal "we").

 So I propose we fix it in 7.8.3.  That is, revert to the original
 numbering in the event log.  But do it with a big switch statement in
 `traceEventStopThread`, rather than undoing the patch that reordered the
 numbers.  Then we won't have this problem again.

 Whether ghc-events is patched to work with 7.8.2 or not is a separate
 matter.  It would be good to do this, but it doesn't change the fact that
 existing ghc-events (and ThreadScope) will give strange results with
 7.8.2.  If ghc-events is fixed, I'd much rather it was done by looking at
 the version number rather than inferring it from something else.  Is that
 really too hard?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9003#comment:5>
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