[Buildbot-commits] [Buildbot] #1001: start_instance on a latent BuildSlave called before stop_instance finished

[Buildbot]

#1001: start_instance on a latent BuildSlave called before stop_instance finished
--------------------+-------------------------------------------------------
Reporter:  moschny  |       Owner:                
    Type:  defect   |      Status:  new           
Priority:  major    |   Milestone:  0.8.3         
 Version:  master   |    Keywords:  virtualization
--------------------+-------------------------------------------------------

Comment(by moschny):

 We do not implement `maybeStartBuild`, maybe that could also be used to
 solve our problem.

 However, if we agree that for each Slave there should only one instance
 running at a time, then isn't it a bug to call `start_instace()` before
 `stop_instance()` has finished?

 We work around this using code like this:
 {{{
 #!text/x-python
 class ChrootSlave(AbstractLatentBuildSlave):

     def __init__(self, *args, **kwargs):
         # ...
         self.mylock = defer.DeferredLock()

     def start_instance(self):
         d = self.mylock.acquire()
         # ...

     def stop_instance(self, fast=False):
         # ...

         def _destroyed(res):
             return self.mylock.release()
         d.addCallback(_destroyed)

         def _releasedLock(res):
             return True
         d.addCallback(_releasedLock)

         return d
 }}}

-- 
Ticket URL: <http://buildbot.net/trac/ticket/1001#comment:5>
Buildbot <http://buildbot.net/>
Buildbot: build/test automation