readline() blocks after select() says there's data??

[Richard Cook]

Thanks, good point.  the actual problem was I was reversing the first 
two args to select.select().  D'oh!

At 6:03 PM +0100 3/15/02, Sjoerd Mullender wrote:
>When select tells you there is something available to read, it doesn't mean
>there is a whole line available to read!  It is very well possible that there
>is only one character available, but readline may want to read (a lot) more
>than that.
>
>Rich Cook wrote:
>>
>>  At 11:09 PM -0600 3/14/02, Skip Montanaro wrote:
>>  >     >>    selectables = [theProcess.childerr, theProcess.fromchild]
>>  >     >>    (input, output, exc) = select.select([],selectables, 
>>selectables)
>>  >     ...
>>  >
>>  >     >> It blocks forever waiting for theProcess.childerr.readline(bufsize)
>>  >     >> to return.  I expect it to block waiting for select.select(); that
>>  >     >> would not be a problem.  The problem is that select is claiming
>>  >     >> there's stuff to be read, then when I try to read it, 
>>it's not there!
>>  >     >> How can that be?
>>  >
>>  >Based upon the attribute names you are using, I suspect you instantiated
>>  >os.Popen3 to create theProcess.  These are file objects, not sockets.  I
>>  >believe select only blocks on sockets.  See the comments about asynchronous
>>  >file i/o near the bottom of asyncore.py.
>>
>>  I don't really need select to block.  I just want it to be accurate.
>>  If it returns a file object in the list of things which are
>>  available, why should then readline() block on it?
>>  --
>>
>>  -Sincerely, Rich Cook 925-784-3077
>>  *******************************************************************
>>  Sometimes it is said that man cannot be trusted with the government
>>  of himself. Can he, then, be trusted with the government of others?
>>           Thomas Jefferson
>>  *******************************************************************
>  >
>  > --
>  > http://mail.python.org/mailman/listinfo/python-list


--