[Haskell-cafe] Having a very annoying problem related with (I think) lazy IO

[Ömer Sinan Ağacan]

Amazing, that really worked. I'm still confused about why this is
happening though.

> it doesn't give other parts of your program to take a lock.

What lock are we talking about here?

2014-12-12 18:33 GMT+02:00 Ömer Sinan Ağacan <omeragacan at gmail.com>:
> Interesting, I think that worked. (I'll try on bigger examples and update again)
>
>> Probably the loop is too fast, and it doesn't give other parts of your
> program to take a lock.
>
> Are there any ways to test for this? How do I know if this is really the case?
>
> 2014-12-12 18:20 GMT+02:00 Yuras Shumovich <shumovichy at gmail.com>:
>> What if you replace the `putStrLn` with `yield` or `threadDelay 1`?
>> Probably the loop is too fast, and it doesn't give other parts of your
>> program to take a lock.
>>
>> On Fri, 2014-12-12 at 17:58 +0200, Ömer Sinan Ağacan wrote:
>>> Hi all,
>>>
>>> I'm having a horrible bug in my program: a print statement that
>>> doesn't force any values(e.g. it just prints a static string)
>>> effecting the behavior of the program.
>>>
>>> I tried hard to produce a minimal example, but couldn't manage it. So
>>> instead I'm just going to point to the source code of my program:
>>> https://github.com/osa1/rho-torrent/blob/master/src/Rho/Listener.hs#L125
>>>
>>> If I remove this print statement everything goes weird. I think when I
>>> remove this statement some effects are not happening, or happening in
>>> wrong times.
>>>
>>> Here's how I'm testing the different behavior: This is a network
>>> application and I'm creating an environment in my system and making
>>> this program talk to another program.
>>>
>>> I run my program 10 times without the print statement, and run 10 times with it.
>>>
>>> Both groups produce same output in every time, but outputs of first
>>> group and second group are different from each other. (apart from
>>> extra prints, of course)
>>>
>>> So this print statement effects some other things, and expected
>>> behavior is the one happening with print statement.
>>>
>>> I know the program is big for anyone to figure things in short amount
>>> of time, I'm just looking for tips and pitfalls that I may be falling.
>>> Does anyone have any ideas what I may be doing wrong? Note that the
>>> program doesn't use any unsafe stuff.
>>>
>>> Thanks in advance.
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>>> Haskell-Cafe at haskell.org
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>>
>>