read stdout/stderr without blocking

Peter Hansen peter at
Fri Sep 16 04:10:52 CEST 2005

Donn Cave wrote:
>  Peter Hansen <peter at> wrote:
>>Jacek Pop³awski wrote:
>>>My tests showed, that it will block.
>>Not if you use non-blocking sockets, as I believe you are expected to 
>>when using select().
> On the contrary, you need non-blocking sockets only if
> you don't use select.  select waits until a read [write]
> would not block - it's like "if dict.has_key(x):" instead of
> "try:  val = dict[x] ; except KeyError:".  I suppose you
> knew that, but have read some obscure line of reasoning
> that makes non-blocking out to be necessary anyway.

No, no, I suspect I was just plain wrong.  I think I felt a twinge of 
suspicion even as I wrote it, but I went ahead and hit Send anyway 
perhaps because I'd had two nights with little sleep (if I need an 
excuse to be wrong, that is, which I don't :-) ).

 > Who knows, but it certainly isn't in this case.

Thanks for straightening things out for the record.


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