I'm having a number of problems with the fcntl module. First off, my
system info:
Mac OS X
Darwin igskcicglthearn.cr.usgs.gov 8.10.1 Darwin Kernel Version
8.10.1: Wed May 23 16:33:00 PDT 2007; root:xnu-792.22.5~1/RELEASE_I386
i386 i386
Python 2.5.1 (built from source)
OK, the weirdness:
First of all, if I try this:
file = open("counter.txt","w+")
fcntl.flock(file.fileno(), fcntl.LOCK_NB)
I get this:
---------------------------------------------------------------------------
<type 'exceptions.IOError'> Traceback (most recent call
last)
/Users/mhearne/src/python/<ipython console> in <module>()
<type 'exceptions.IOError'>: [Errno 9] Bad file descriptor
However, if I try this:
fcntl.flock(file.fileno(), fcntl.LOCK_EX)
I get no errors.
Proceeding forward with the locked file, let's say I do the above in
Python interactive Process A. Then in python interactive Process B, I
repeat the "open" function on the same file with the same
permissions. Then, in each process, I write some text to the file
using the write() method. After closing the file in both processes,
the only text I see in the file is from Process B!
According to my Python Cookbook:
"Exclusive lock: This denies all _other_ processes both read and write
access to the file."
I seem to be experiencing the reverse of that description. Is this my
lack of understanding, or have I discovered a bug?
Thanks,
Mike
--
http://mail.python.org/mailman/listinfo/python-list
