Way to unblock sys.stdin.readline() call

[joamag]

HI,

Is there any possible way to unblock the sys.stdin.readline() call
from a different thread.
Something like sys.stdin.write() but that would actually work ...
something to put characters in the stdin...

Thanks in advance,
João

 

[Cédric Lucantis]

Le Saturday 21 June 2008 15:26:53 joamag, vous avez écrit :

HI,

Is there any possible way to unblock the sys.stdin.readline() call
from a different thread.
Something like sys.stdin.write() but that would actually work ...
something to put characters in the stdin...

Do you mean setting stdin in non-blocking mode ? On unix you can do it with
the fcntl module (you'll find more infos in the libc docs) :

fcntl.fcntl(sys.stdin, fcntl.F_SETFL, os.O_NONBLOCK)

and catch IOErrors with errno = EAGAIN. But I don't know how to do it in a
portable way, suggestions welcome

 

[joamag]

Le Saturday 21 June 2008 15:26:53 joamag, vous avez écrit :



Do you mean setting stdin in non-blocking mode ? On unix you can do it with
the fcntl module (you'll find more infos in the libc docs) :

fcntl.fcntl(sys.stdin, fcntl.F_SETFL, os.O_NONBLOCK)

and catch IOErrors with errno = EAGAIN. But I don't know how to do it in a
portable way, suggestions welcome

Thanks for the advice that's a way of solving my problem, but I really
need a portable way of doing it...

The application I’m build is meant to be run in more platforms than
Unix ... so I really need a portable way of doing that or something
else that unblocks the read call in the stdin

 

[Terry Reedy]

Is there any possible way to unblock the sys.stdin.readline() call
from a different thread.

If you want the thread to do something 'else' when no input is
available, would this work? Put readline in a thread that puts lines in
a q=queue.Quese(). Then
try:
l=q.ge_nowait
<process l>
except queue.Empty
<whatever without l>

 

[joamag]

If you want the thread to do something 'else' when no input is
available, would this work?  Put readline in a thread that puts lines in
a q=queue.Quese().  Then
try:
     l=q.ge_nowait
     <process l>
except queue.Empty
     <whatever without l>

Yes, that would work but still I would have a thread that would block
(the one with the readline call).
The problem with that solution is that if I try to exit the
application, while the thread is waiting in the readline call, that
thread would be blocking the exit of the application.
That behavior occurs even if the thread is configured in daemon mode.
Do you think it’s possible to solve the readline blocking problem in
any other way ?