How to safely maintain a status file
gandalf at shopzeus.com
Thu Jul 12 19:43:19 CEST 2012
>> This is not a contradiction. Although the rename operation is atomic,
>> the whole "change status" process is not. It is because there are two
>> operations: #1 delete old status file and #2. rename the new status
>> file. And because there are two operations, there is still a race
>> condition. I see no contradiction here.
> On Posix systems, you can avoid the race condition. The trick is to
> skip step #1. The rename will implicitly delete the old file, and
> it will still be atomic. The whole process now consists of a single
> stop, so the whole process is now atomic.
Well, I didn't know that this is going to work. At least it does not
work on Windows 7 (which should be POSIX compatible?)
>>> f = open("test.txt","wb+")
>>> f2 = open("test2.txt","wb+")
>>> import os
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
WindowsError: [Error 183] File already exists
I have also tried this on FreeBSD and it worked.
Now, let's go back to the original question:
>>>This works well on Linux but Windows raises an error when status_file already exists.
It SEEMS that the op wanted a solution for Windows....
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