[mod_python] RuntimeError: dictionary changed size during iteration

The mem_cleanup routine, in Session.py, appears to have a bug that causes
python to throw "dictionary changed size during iteration".

The current code is.

def mem_cleanup(sdict):
    for sid in sdict:
        dict = sdict[sid]
        if (time.time() - dict["_accessed"]) > dict["_timeout"]:
            del sdict[sid]

The for statement should be changed to
    for sid in sdict.keys():

This will first generate a list of the keys of the sdict, and will avoid the
complaint about the dictionary changing on the "del sdict[sid]" statement.

The dbm_cleanup code has another approach, to use one iteration to gather
the keys to be deleted, and then have a second iteration over the gathered
keys which does the del.   Using that approach, mem_cleanup should become...

def mem_cleanup(sdict):
    old = []
    for sid in sdict:
        dict = sdict[sid]
        if (time.time() - dict["_accessed"]) > dict["_timeout"]:
            old.append(sid)
    for sid in old:
        del sdict[sid]

This is more efficient if the number of sessions is large compared to the
number of sessions to be deleted.

Shack Toms
LiveData, Inc.