#1657: throwTo + unsafeInterleaveIO oddness
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Reporter: guest | Owner:
Type: bug | Status: merge
Priority: normal | Milestone: _|_
Component: Runtime System | Version: 6.6.1
Keywords: | Testcase:
Blockedby: | Difficulty: Unknown
Os: Windows | Blocking:
Architecture: x86 | Failure: None/Unknown
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Changes (by simonmar):
* status: new => merge
Comment:
This is probably the same issue as #3997, which I fixed in the IO library.
The underlying problem is that when an asynchronous exception is caught
and re-thrown, it is thrown synchronously. This only makes a difference
inside `unsafePerformIO` and `unsafeInterleaveIO`, where there might be a
resumable computation that will be updated with the exception. In order
to fix this, the asynchronous exception has to be re-thrown
asynchronously, which is possible (using `myThreadId` and `throwTo`), but
then the exception handler has to be prepared to resume when the enclosing
computation is demanded. In the case of the IO library we arranged that
the IO operation is re-done, but in general what to do is application-
specific.
So I'm going to close this bug, I don't think there's anything else we can
do.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1657#comment:10>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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