Permission denied when opening a file that was created concurrently by os.rename (Windows)

Terry Reedy tjreedy at
Sun Apr 5 22:10:06 CEST 2015

On 4/5/2015 1:45 PM, Alexey Izbyshev wrote:
> Hello!
> I've hit a strange problem that I reduced to the following test case:
> * Run several python processes in parallel that spin in the following loop:

> while True:
>    if os.path.isfile(fname):
>      with open(fname, 'rb') as f:
>      break

Besides anything else, I would consider adding a minimal sleep in the loop.

> * Then, run another process that creates a temporary file and then
> renames it to the name than other processes are expecting
> * Now, some of the reading processes occasionally fail with "Permission
> denied" OSError

Terry Jan Reedy

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