Several buildsteps in the yocto-autobuilder call self.finished() and/or self.build.stopBuild() *before* the Command.start() has been called. This results in an exception which doesn't (noticeably) have an effect on the build but does clutter the autobuilders logs, making it harder to find errors which are affecting builds. Example of the traceback: 2016-12-12 03:09:35+0000 [-] BuildStep.startStep exception in .start 2016-12-12 03:09:35+0000 [-] BuildStep.failed; traceback follows Traceback (most recent call last): File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/Twisted-12.2.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py", line 551, in _runCallbacks current.result = callback(current.result, *args, **kw) File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/Twisted-12.2.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py", line 1187, in unwindGenerator return _inlineCallbacks(None, gen, Deferred()) File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/Twisted-12.2.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py", line 1045, in _inlineCallbacks result = g.send(result) File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/buildbot-0.8.8-py2.7.egg/buildbot/process/buildstep.py", line 605, in _startStep_3 result = yield defer.maybeDeferred(self.start) --- <exception caught here> --- File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/Twisted-12.2.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py", line 134, in maybeDeferred result = f(*args, **kw) File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/autobuilder/buildsteps/ResolveLayerHead.py", line 57, in start self.command = cmd exceptions.UnboundLocalError: local variable 'cmd' referenced before assignment 2016-12-12 03:09:35+0000 [-] exception during failure processing Traceback (most recent call last): File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/Twisted-12.2.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py", line 1187, in unwindGenerator return _inlineCallbacks(None, gen, Deferred()) File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/Twisted-12.2.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py", line 1043, in _inlineCallbacks result = result.throwExceptionIntoGenerator(g) File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/Twisted-12.2.0-py2.7-linux-x86_64.egg/twisted/python/failure.py", line 382, in throwExceptionIntoGenerator return g.throw(self.type, self.value, self.tb) File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/buildbot-0.8.8-py2.7.egg/buildbot/process/buildstep.py", line 610, in _startStep_3 self.failed(Failure()) --- <exception caught here> --- File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/buildbot-0.8.8-py2.7.egg/buildbot/process/buildstep.py", line 686, in failed self.progress.finish() File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/buildbot-0.8.8-py2.7.egg/buildbot/status/progress.py", line 85, in finish self.buildProgress.stepFinished(self.name) File "/home/pokybuild/yocto-autobuilder/lib/python2.7/site-packages/buildbot-0.8.8-py2.7.egg/buildbot/status/progress.py", line 165, in stepFinished assert(stepname not in self.finishedSteps) exceptions.AssertionError:
BuildStep.finished()[1] states "The step should not perform any additional processing after calling this method." yet many of our build steps call finished() before they call start()[2] 1. http://docs.buildbot.net/0.8.8/developer/cls-buildsteps.html#buildbot.process.buildstep.BuildStep.finished 2. http://docs.buildbot.net/0.8.8/developer/cls-buildsteps.html#buildbot.process.buildstep.BuildStep.start
I've identified a few patterns to avoid calling start() after finished() has been called without significantly refactoring the affected buildsteps.
Asked to Joshua, he said it's ok to change this bug to Verified.