[ ghc-Bugs-1370370 ] panic! 'impossible' happened, thread blocked indefinitely

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Bugs item #1370370, was opened at 2005-11-30 13:04
Message generated for change (Tracker Item Submitted) made by Item Submitter
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Category: GHCi
Group: 6.4.1
Status: Open
Resolution: None
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: panic! 'impossible' happened, thread blocked indefinitely

Initial Comment:
GHCi, version 6.4.1, crashed with the following error: 
 
ghc-6.4.1: panic! (the `impossible' happened, GHC 
version 6.4.1): 
        thread blocked indefinitely 
 
Please report it as a compiler bug to 
glasgow-haskell-bugs at haskell.org, 
or http://sourceforge.net/projects/ghc/. 
 
I was calling a test function which was forking a 
Thread which was blocking in an 'atomically' waiting 
on a TChan. 
If I ran the test function a second time, while the 
Thread from the first run is presumably still hanging 
around, I would receive the above error/crash. 
 
If I reloaded the source in GHCi after running the 
test function a single time GHCi would give an error 
message (but not crash): 
 
*** Exception: thread blocked indefinitely 
 
Most of the time after the error message there would 
be no modules loaded.  I could load again, and repeat 
the fun. 
_Very_ occasionaly the modules would remain loaded and 
I could repeat the cycle without having to reload the 
modules. 
 
Since fixing my test function so the forked Thread 
dies at the desired time (ie now it won't be hanging 
around blocked on the TChan) I haven't observed the 
failure. 
 
My email: kgrapone at gmail.com 

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