On Fri, 2 Dec 2016 11:26 am, DFS wrote:
>> For most programs, yes, it probably will never be a problem to check
>> for existence, and then assume that the file still exists. But put that
>> code on a server, and run it a couple of million times, with dozens of
>> other processes also manipulating files, and you will see failures.
>
>
> If it's easy for you, can you write some short python code to simulate
> that?
Run these scripts simultaneously inside the same directory, and you will see
a continual stream of error messages:
# -- a.py --
filename = 'data'
import os, time
def run():
if os.path.exists(filename):
with open(filename):
pass
else:
print('file is missing!')
# re-create it
with open(filename, 'w'):
pass
while True:
try:
run()
except IOError:
pass
time.sleep(0.05)
# -- b.py --
filename = 'data'
import os, time
while True:
try:
os.remove(filename)
except OSError:
pass
time.sleep(0.05)
The time.sleep() calls are just to slow them down slightly. You can leave
them out if you like.
--
Steve
“Cheer up,” they said, “things could be worse.” So I cheered up, and sure
enough, things got worse.
--
https://mail.python.org/mailman/listinfo/python-list
