Re: opensm/main.c: foce stdout to be line-buffered

[Yevgeny Kliteynik <kliteyn-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>]

On 23/Mar/10 23:36, Yevgeny Kliteynik wrote:
> On 23/Mar/10 18:37, Sasha Khapyorsky wrote:
>> On 14:25 Tue 23 Mar , Yevgeny Kliteynik wrote:
>>>
>>> I'm running "opensm> somefile", and I don't see SM's stdout
>>> (such as "SUBNET UP" message, or new cached options after SIGHUP),
>>> because when stdout is assigned to file and not terminal, it is
>>> handled differently. Instead of flushing on printing '\n',
>>> it becomes buffered, which means that you don't control when
>>> is this buffer flushed.
>>> My fix forces stdout to always flush stdout when printing '\n'.
>>> It has no effect when stdout is assigned to terminal, and it
>>> changes buffering when SM's stdout is redirected.
>>>
>>> More details about stdout/stderr buffering:
>>>
>>> http://www.pixelbeat.org/programming/stdio_buffering/
>>
>> There you can find couple of ways to workaround this issue, for example:
>>
>> stdbuf -o L opensm> somefile
>
> This is not a usual shell command, nor some common
> tool that is used in Linux distros. It's just a tool
> that is provided in some package called "coreutils 7.5".

Correction: the coreutils package is common, stdbuf isn't -
it was added in coreutils 7.5.
For instance, RH 5.3 has version 5.97, SLES 11 has version
6.12

-- Yevgeny

>> I would prefer to not change an external settings so the program would
>> work as expected.
>
> IMHO, on the contrary - the expected behavior
> would be achieved with the patch.
>
> But in any case, what exactly seems problematic here?
>
> I can't see any impact on any aspect whatsoever.
> It is somehow related to performance (more flushes
> when the stream is line-buffered instead of just
> buffered), but we're talking about stdout here, not
> the log file, so the performance is not affected too.
>
> -- Yevgeny
>
>> Sasha
>>
>
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