how to remove oldest files up to a limit efficiently

[Terry Reedy]

Dan Stromberg wrote:
> On Tue, 08 Jul 2008 15:18:23 -0700, linuxnow at gmail.com wrote:
> 
>> I need to mantain a filesystem where I'll keep only the most recently
>> used (MRU) files; least recently used ones (LRU) have to be removed to
>> leave space for newer ones. The filesystem in question is a clustered fs
>> (glusterfs) which is very slow on "find" operations. To add complexity
>> there are more than 10^6 files in 2 levels: 16³ dirs with equally
>> distributed number of files inside.
>
>> Any suggestions of how to do it effectively?
> 
> os.walk once.
> 
> Build a list of all files in memory.
> 
> Sort them by whatever time you prefer - you can get times from os.stat.

Since you do not need all 10**6 files sorted, you might also try the 
heapq module.  The entries into the heap would be (time, fileid)