[GHC] #10414: Buggy behavior with threaded runtime (-N1 working, -N2 getting into <<loop>>)

[GHC]

#10414: Buggy behavior with threaded runtime (-N1 working, -N2 getting into
<<loop>>)
-------------------------------------+-------------------------------------
        Reporter:  exio4             |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by michaelt):

 rwbarton, I think I have tested all of these examples on my machine, for
 it's worth.

 I rebuilt HEAD with what I took to be the patch  described above:

 {{{
 -     LFThunk _ _no_fvs _updatable _ _ -> True
 +     LFThunk _ _no_fvs _updatable _ _ -> _updatable
 }}}

 for
 https://github.com/ghc/ghc/blob/master/compiler/codeGen/StgCmmClosure.hs#L769
 .


 Everything works fine, or seems to work fine.

 The complex program yongqli linked, with all the fancy imports, was a
 little erratic; I increased the size of the csv a lot, to make it more
 reliably bad somewhere along the way. I then just used the scheme of
 running `  ./bugcsv +RTS -N_ | grep loop `  500 times each with -N5 and
 -N3 . (-N2 does't seem to make bring out the pathology with this program.)
 With ghc-7.10.1 I got

 `bugcsv: <<loop>>`

 about 200 times either way, but with the patched head, blessed silence.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10414#comment:26>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler