[FIXED] python 2.x:Conditionally Catching Exceptions (Ignore gracefully cleanup if the file is missing)

Issue

I am having a script which cleanups the logs older than 14 days at a shared location. Now this script can run at same time from different host. In a particular situation if two or more hosts try to cleanup same file, only one will succeed and all other gives error "No such file or directory". How can I update the code to Ignore gracefully cleanup if the file suddenly goes missing. Below is part of code which is performing the cleanup. count tracks the number of files deleted.

if os.stat(filename).st_mtime < current_time - 14 * 86400:
    try:
       os.remove(filename)
       count += 1
    except:
       logger.warning("Not able to delete the file %s" % filename)

One way is to "pass" the exception if file dont exist but continue to log warning if you are not able to delete the file. How to include this condition.

Solution

As @Mark suggests you could check beforehand if the file exists and then delete it but there is still a potential race condition in such an approach. It can occur between script's instances after os.stat and before os.remove. Moving all of the code raising errors to try / except should do the job. However, as I understand there is a problem with logging a truthful message. Additional flag attempted_delete should help with that:

attempted_delete = False
try:
    if os.stat(filename).st_mtime < current_time - 14 * 86400:
         os.remove(filename)
         count += 1
         attempted_delete = True
except:
     if attempted_delete:
         logger.warning("Not able to delete the file %s" % filename)

Answered By - sophros