Problems on select module on Python 2.5

Question

I have an application in Python 2.5 that listens to a beanstalk queue. It works fine on all machines I tested so far, except from my newly acquired MacBook Pro.

On that computer, when I try to run it I get this error:

Traceback (most recent call last):
  File "jobs.py", line 181, in <module>
    Jobs().start()
  File "jobs.py", line 154, in start
    self.jobQueue = Queue()
  File "src/utils/queue.py", line 16, in __init__
    self.connection = serverconn.ServerConn(self.server, self.port)
  File "src/beanstalk/serverconn.py", line 25, in __init__
    self.poller = select.poll()
AttributeError: 'module' object has no attribute 'poll'

The serverconn.py has the following imports:

import socket, select

And when I try to run it from command line, it fails as well:

Python 2.5.1 (r251:54863, Jul 23 2008, 11:00:16) 
[GCC 4.0.1 (Apple Inc. build 5465)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import select
>>> select.poll()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'poll'

Do you have any idea on what can be happening?

PS: Even though I am pretty confident it's not a source problem, if you need some background on the source that's failing, it's available at [http://pastie.org/399342](this pastie).

Updated: since the first answer I got speculates whether select.poll() is or not supported on Mac OS, but I have an iMac too and with the exact same OS version and it works fine:

2009-02-25 00:27:10,067 - Queue - DEBUG - Connecting to BeansTalk daemon @ localhost:11300

Answer 1

use the MacPorts version of python on your MBP.

Mac OS X supports this. Apple stock Leopard python 2.5.1 does not.

you will want to download and install MacPorts if you have not already. FYI, I find Porticus to be an excellent GUI around MacPorts.

here is a comparison of stock Leopard python vs. latest MacPorts python2.5...

---

Leopard python from Apple (python 2.5.1) - select.poll() broken

$ /usr/bin/python
Python 2.5.1 (r251:54863, Jan 13 2009, 10:26:13) 
[GCC 4.0.1 (Apple Inc. build 5465)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import socket, select
>>> select.poll()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'poll'
>>> 

Macports (python 2.5.4) - select.poll() works!

$ /opt/local/bin/python2.5
Python 2.5.4 (r254:67916, Feb  3 2009, 21:40:31) 
[GCC 4.0.1 (Apple Inc. build 5488)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import socket, select
>>> select.poll()
<select.poll object at 0x11128>
>>> 

Answer 2

According to this macports ticket Apple's implementation of poll() is straight up broken. Apple worked around this by disabling poll() in Python and macports now disables poll in their Pythons as well. I think this means you need to look into Python's select.kevent() instead of poll on mac.

Answer 3

I think your answer is here

http://atomized.org/2008/12/python-on-os-x-leopard-lacks-selectpoll/

Answer 4

select.poll()

(Not supported by all operating systems.) Returns a polling object, which supports registering and unregistering file descriptors, and then polling them for I/O events; see section Polling Objects below for the methods supported by polling objects.

My guess is that it's not supported on the macOS.