#6041: Program hangs when run under Ubuntu Precise
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Reporter: dsf | Owner:
Type: bug | Status: closed
Priority: high | Milestone: 7.4.2
Component: Compiler | Version: 7.4.1
Resolution: invalid | Keywords:
Os: Linux | Architecture: Unknown/Multiple
Failure: Runtime crash | Difficulty: Unknown
Testcase: | Blockedby:
Blocking: | Related:
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Comment(by guest):
@cliffordbeshers: Does the original Main.hs given by dsf gives <<loop>> on
your machine while my reduced version does not? That would be extremely
strange and if so I would reopen the ticket. I can reproduce looping on
both programs, with Ubuntu Precise, 3.2.0-25-generic-pae, GHC 7.4.1.
I am pretty sure of my overall diagnosis. Please note that all fixes (1) -
(4) given in initial bug report are connected to the state monad. The
program puts infinite loop as a state with `modify id`, and then attempts
to read it with `readTVar u`. For example, if you change `_ <- liftIO $
atomically $ readTVar u` to `print $ seq u ()`, the behaviour is the same,
indicating that TVars are not core of the issue and can be replaced with
().
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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6041#comment:17>
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