Hi Gordon, On Mon, Jul 13, 2009 at 11:40 +1000, Gordon Wrigley wrote: > > One issue that can pop up is tearing down the whole > > machinery cleanly - that can sometimes be more > > involved and i believe execnet still might need > > some more work there. > > On that note can you shed any light on this message: > > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel._del_ of <Channel id=7 > open>> ignored > > Currently I'm only seeing them on my test machine, but they are > occurring very frequently, they drop out at the end of the py.test > invocation, I will paste the tail end of the py.test output below.
> I'm not sure exactly what is causing this, naively it seems to > indicate a circular chain of references involving one or more > channels. However immediately prior to the conclusion of each test > exit gc.garbage is empty and there are none of my objects in > gc.get_objects. Yes, some cycle is probably there. Your data point hints that there is some cycle in the execnet code itself. > Also this only started when I reworked our remote invocation system > recently, the most notable change in the new system is that it makes > more use of threads and particularly it has daemon threads waiting on > channel receive calls. Hum, that might be related - GC-finalization issues in MT-environments are not easy to debug :( Might also be python-version dependent. What are the differences between your test and production system? I am a bit at a loss on how to best proceed at the moment. I think that adding more debugging information to execnet and systematically implementing and checking scenarios is due - but quite a bit of effort. Could you maybe try coming up with an self-contained example test-script leading to these messages? On a sidenote, probably around 60% of the execnet core programming effort revolve around teardown/finalization issues - i wonder if it would be better to avoid usage of __del__ alltogether, only have a process-wide atexit handler and otherwise recommend explicit calling of gateway.exit()/channel.close methods for proper resource handling. best, holger > l...@okum:~$ uname -a > Linux okum 2.6.28-11-generic #42-Ubuntu SMP Fri Apr 17 01:57:59 UTC > 2009 i686 GNU/Linux > l...@okum:~$ python > Python 2.6.2 (release26-maint, Apr 19 2009, 01:56:41) > [GCC 4.3.3] on linux2 > Type "help", "copyright", "credits" or "license" for more information. > >>> import py > >>> py.version > '1.0.0b1' > > > ============================================== 35 passed in 231.71 > seconds =============================================== > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in Unhandled exception in thread started by <bound > method Thread.__bootstrap of <Thread(receiver, stopped daemon > 1177635728)>> > <bound method Channel.__del__ of <Channel id=7 open>>Error in sys.excepthook: > Traceback (most recent call last): > File "/usr/lib/python2.6/dist-packages/apport_python_hook.py", line > 38, in apport_excepthook > from apport.packaging_impl import impl as packaging > ImportError: No module named apport.packaging_impl > > Original exception was: > Traceback (most recent call last): > File "/usr/lib/python2.6/threading.py", line 497, in __bootstrap > self.__bootstrap_inner() > File "/usr/lib/python2.6/threading.py", line 538, in __bootstrap_inner > (self.name, _format_exc())) > TypeError: 'NoneType' object is not callable > ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > Exception AttributeError: "'NoneType' object has no attribute > 'CHANNEL_CLOSE'" in <bound method Channel.__del__ of <Channel id=7 > open>> ignored > 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