Re: python reference leaks

On Fri, Apr 15, 2005 at 10:11:18PM -0400, Jack Diederich wrote:
> I've been getting segfaults running metakit in a persistent python interpreter
> (under mod_python, so the interpreter lives for a long time).  I just checked
> out the metakit head (on the server I'm running 2.4.9.3) and jcw figured out
> how to initialize under a python debug build[1] so here is what I can report:
> 
> This is a debug python build so when run interactively it outputs the number 
> of live references after every command.
> 
> The tst.py is just
> import metakit
> import gc
> def round1():
>   def round1():
>   fname = '/tmp/test.mk'
>   stor = metakit.storage(fname, 2)
>   gc.collect() # force cleanup on unreachable objects
>   return
> 
> here is the interactive output, with reference counts.
> 
> Python 2.4.1 (#1, Apr 15 2005, 21:18:43) 
> [GCC 3.3.5 (Debian 1:3.3.5-12)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import tst
> [23817 refs]
> >>> tst.round1()
> [23820 refs]
> >>> tst.round1()
> [23823 refs]
> >>> tst.round1()
> [23826 refs]
> >>> tst.round1()
> [23829 refs]
> 
> So opening a new storage is leaking three refs per go.
> I ran the same test with some python objects I know don't leak (dicts
> and lists) as a sanity test and the #refs after each call stayed static, 
> 
> I'll try and hunt down the leak, but if anyone has any ideas let me know.
> 

Some digging, PyStorage objects are created & destroyed with appropriate
refcounts.  Some of the auxilliary objects created in PyStorage_new leak.

// PyStorage.cpp line 370-ish
  // returning here leaks no refs per call
  PWOString fnm(args[0]);
  // returning here leaks 1 ref per call
  if (PyInt_Check((PyObject* )args[1])) {
    PWONumber mode (args[1]);
    ps = new PyStorage(fnm, mode);
    if (!ps->Strategy().IsValid()) {
  }
  // returning here leaks more (3) refs per call

Closer still ..
_____________________________________________
Metakit mailing list  -  [email protected]
http://www.equi4.com/mailman/listinfo/metakit