files in non-blocking mode?

[Uwe Mayer]

Hi,

I want two python programs to communicate over stdIO channels. The one
executes the other via the popen3 function:

amc = Popen3("./amc/amc.py", True, 0)
line = stdin.readline( )
amc.tochild.wri te(line)
amc.tochild.flu sh()
print amc.fromchild.r eadlines()

The problem is that although amc.tochild gets flushed the data never reaches
the client until the .tochild fd is closed. Is there any way to put IO
channels into non-blocking mode in python?

Thanks
Uwe

[Mathias Waack]

Re: files in non-blocking mode?

Uwe Mayer wrote:
[color=blue]
> Hi,
>
> I want two python programs to communicate over stdIO channels. The
> one executes the other via the popen3 function:
>
> amc = Popen3("./amc/amc.py", True, 0)
> line = stdin.readline( )
> amc.tochild.wri te(line)
> amc.tochild.flu sh()
> print amc.fromchild.r eadlines()
>
> The problem is that although amc.tochild gets flushed the data
> never reaches the client until the .tochild fd is closed. Is there
> any way to put IO channels into non-blocking mode in python?[/color]

How do you read the data in the client? Maybe you're using a line
buffered read? Does your code work if the server includes a trailing
CR and/or NL in the string before it calls the flush?

Mathias

[Uwe Mayer]

Re: files in non-blocking mode?

Sunday 28 November 2004 14:49 pm Mathias Waack wrote:
[color=blue]
> Uwe Mayer wrote:[color=green]
>> I want two python programs to communicate over stdIO channels. The
>> one executes the other via the popen3 function:
>>
>> amc = Popen3("./amc/amc.py", True, 0)
>> line = stdin.readline( )
>> amc.tochild.wri te(line)
>> amc.tochild.flu sh()
>> print amc.fromchild.r eadlines()
>>
>> The problem is that although amc.tochild gets flushed the data
>> never reaches the client until the .tochild fd is closed. Is there
>> any way to put IO channels into non-blocking mode in python?[/color][/color]
[color=blue]
> How do you read the data in the client? Maybe you're using a line
> buffered read? Does your code work if the server includes a trailing
> CR and/or NL in the string before it calls the flush?[/color]

Yes, I used

line = stdin.readline( )

and made sure the sending client had a newline ("\n") char appended to the
text. Still, the receiving client's readline() function does not return.

Uwe

[Jean Brouwers]

Re: files in non-blocking mode?


Try setting the unbuffered mode for the spawned process by using

"python -u ./amc/amc.py"


/Jean Brouwers


In article <cocrun$qqu$1@n ews2.rz.uni-karlsruhe.de>, Uwe Mayer
<merkosh@hadiko .de> wrote:
[color=blue]
> Sunday 28 November 2004 14:49 pm Mathias Waack wrote:
>[color=green]
> > Uwe Mayer wrote:[color=darkred]
> >> I want two python programs to communicate over stdIO channels. The
> >> one executes the other via the popen3 function:
> >>
> >> amc = Popen3("./amc/amc.py", True, 0)
> >> line = stdin.readline( )
> >> amc.tochild.wri te(line)
> >> amc.tochild.flu sh()
> >> print amc.fromchild.r eadlines()
> >>
> >> The problem is that although amc.tochild gets flushed the data
> >> never reaches the client until the .tochild fd is closed. Is there
> >> any way to put IO channels into non-blocking mode in python?[/color][/color]
>[color=green]
> > How do you read the data in the client? Maybe you're using a line
> > buffered read? Does your code work if the server includes a trailing
> > CR and/or NL in the string before it calls the flush?[/color]
>
> Yes, I used
>
> line = stdin.readline( )
>
> and made sure the sending client had a newline ("\n") char appended to the
> text. Still, the receiving client's readline() function does not return.
>
> Uwe[/color]