Self healthcheck

[Chris Angelico]

On Wed, Jan 22, 2014 at 1:51 PM, Asaf Las <roegltd at gmail.com> wrote:
> When designing long running background process
> is it feasible to monitor object/memory leakage due
> to improper programming?

I assume you're talking about pure Python code, running under CPython.
(If you're writing an extension module, say in C, there are completely
different ways to detect reference leaks; and other Pythons will
behave slightly differently.) There's no way to detect truly
unreferenced objects, because they simply won't exist - not after a
garbage collection run, and usually sooner than that. But if you want
to find objects that you're somehow not using and yet still have live
references to, you'll need to define "using" in a way that makes
sense. Generally there aren't many ways that that can happen, so those
few places are candidates for a weak reference system (maybe you map a
name to the "master object" representing that thing, and you can
recreate the master object from the disk, so when nothing else is
referring to it, you can happily flush it out - that mapping is a good
candidate for weak references).

But for most programs, don't bother. CPython is pretty good at keeping
track of its own references, so chances are you don't need to - and if
you're seeing the process's memory usage going up, it's entirely
possible you can neither detect nor correct the problem in Python code
(eg heap fragmentation).

ChrisA