finalizers on handles

[Brandon S. Allbery KF8NH]

On Jun 24, 2009, at 00:52 , Ganesh Sittampalam wrote:
> On Tue, 23 Jun 2009, Brandon S. Allbery KF8NH wrote:
> On Jun 23, 2009, at 09:41 , Simon Marlow wrote:
>>>> main = do
>>>> (ih, oh, _, _) <- runInteractiveProcess "cat" [] Nothing Nothing
>>>> comphszp <- hGetContents oh
>>>> print (length comphszp)
>>>> -- hClose ih -- with this line they both deadlock
>>
>>
>> Note that you can trigger this in any language; it's a classic  
>> beginner error with pipes (see, for example, the documentation for  
>> open2/open3 in Perl or Python for other examples).  Detecting this  
>> in the type system would be an interesting idea, but de facto I  
>> think this is a "it hurts when I do this".
>
> Sure - but it hurts more when in some environments you get away with  
> it and others you don't.


You'll still have that though, it'll just be a different set of  
environments.  The next failure mode after this one is writing more  
than _PIPE_BUF down ih; you'll deadlock in the write when in blocking  
mode, in non-blocking mode it depends on how the runtime handles  
partial writes.

-- 
brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery at kf8nh.com
system administrator [openafs,heimdal,too many hats] allbery at ece.cmu.edu
electrical and computer engineering, carnegie mellon university    KF8NH


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