writeFile/readFile on multiple threads leads to error

[Neil Mitchell]

Bulat: I haven't tried moving to Posix calls, I'll try that next -
although I was hoping the application wouldn't be posix dependent.

>> readFile calls openFile >>= hGetContents. It's the openFile that
>> causes the problem, so READ START happens before openFile and READ
>> STOP happens after openFile. The lazy semantics of the actual reading
>> don't seem to have an effect.
>
> Just want to make sure that it isn't the latent hClose from readFile.

Yeah, I've done that before! It seems to be the writeFile that isn't
closing, not the readFile - hence my surprise.

>> I did try changing to the strict bytestring file read, and that gave
>> exactly the same error - apart from openBinaryFile was crashing rather
>> than openFile.
>
> Weren't there versions of bytestring that didn't close the file early
> enough?

I only used bytestring for reading, so it shouldn't have made any difference.

Thanks

Neil