BIND 10 #1359: reference leak in python log wrapper

[BIND 10 Development]

#1359: reference leak in python log wrapper
-------------------------------------+-------------------------------------
                   Reporter:         |                 Owner:  jinmei
  jinmei                             |                Status:  accepted
                       Type:         |             Milestone:
  defect                             |  Sprint-20111122
                   Priority:  major  |            Resolution:
                  Component:         |             Sensitive:  0
  logging                            |           Sub-Project:  Core
                   Keywords:         |  Estimated Difficulty:  4
            Defect Severity:  N/A    |           Total Hours:  0
Feature Depending on Ticket:         |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Comment (by jinmei):

 trac1359 is ready for review.

 I've found a more critical leak in the log wrapper, and succesfully
 reproduced clear memory leak with the following simple test code:
 {{{
 while True:
     name = isc.dns.Name('example.com')
     rrclass = isc.dns.RRClass('IN')
     logger.info(XFRIN_XFR_TRANSFER_SUCCESS, 'AXFR',
                 name.to_text(True) + '/' + str(rrclass))
     logger.error(XFROUT_CC_SESSION_TIMEOUT_ERROR)
 }}}
 (of course you'll need to import necessary modules and set PYTHONPATH,
 etc,
 properly).

 I've fixed the leak in this branch, and confirmed it completely solves
 this type of memory leak.

 Since the main fix is pretty small and (I believe) straightforward,
 I've also made some additional cleanups (some of which are actually
 not just for cleanness but fixes rare exception safety bugs).  The
 main fix is the first two commits.  If the additional changes are
 deemed to be beyond the scope of this ticket, I'm okay with deferring
 them to a separate ticket.

 This is the proposed changelog entry:
 {{{
 317.    [bug]           jinmei
         Fixed reference leak in the isc.log Python module.  Most of all
         BIND 10 Python programs had memory leak (even though the pace of
         leak may be slow) due to this bug.
         (Trac #1359, git TBD)
 }}}

 BTW, this is totally unrelated to this ticket, but I've been also
 noticing that in the python log wrapper converts the expensive
 conversion from objects to string for all log levels.  I guess this
 has non negligible performance impact even if performance is
 relatively less crucial for python programs.  I wonder whether we
 should do the isXXXEnabled() check in Logger_debug(), etc, before
 calling Logger_performOutput.  Would that be worth trying, maybe
 in a separate ticket?

-- 
Ticket URL: <http://bind10.isc.org/ticket/1359#comment:4>
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