Doesn't work on Ubuntu 14.04, python 2.7.6?

[vladiibine]

So I did this in one python console (the file already existed)

import portalocker as pl
f1 = open('./asdf', 'w')
pl.lock(f1, pl.LOCK_EX)

Then in another python console I did this

f1 = open('./asdf', 'w')
f1.write('zzzzzzzzzzzzzzzzfdffffffffffffffffffffffffff')
f1.close()

Then I do this in a bash console

$ cat ./asdf
zzzzzzzzzzzzzzzzfdffffffffffffffffffffffffff

Am I missing something about how this is supposed to work, or does it just not lock the file?

[wolph]

It does actually lock the file but on Ubuntu the code uses flock() internally, these locks are advisory which means there is no actual requirement to follow the locking.

Just execute the code from your console in 2 separate consoles and you will notice the locks but as far as I know there is no standard way to force locking on Ubuntu without changing your mounts to mandatory locking (with -o mand). But even these are known to be buggy unfortunately.