Hi Bill, you are right that the SchedulingFilter deals with constraints. However, the preemptor seems to be reacting poorly when a job cannot be scheduled due to such a constaint. Let me explain.
The preemptor cannot distinguish whether he sees a veto because of a mismatched constraint or due to a lack of free resources on a slave. He assumes the latter and therefore begins preempting tasks until the whole slave has been drained. He returns happily, even though the task can still not be scheduled. At least that is the way I do read the code... Best, Stephan On So, 2014-09-14 at 08:49 -0700, Bill Farner wrote: > Thanks for raising the concern! > > > Unfortunately, it seems the preemptor cannot handle constraints > > Sounds like you are saying the Preemptor is only matching resources and not > constraints? > > I'm on a phone, so I may have missed something, but my read is that the > preemptor lets SchedulingFilter.filter deal with satisfying constraints. > > On Sunday, September 14, 2014, Stephan Erb <step...@dev.static-void.de> > wrote: > > > Hi together, > > > > I was scrolling through Preemptor.java and noticed that tasks might be > > preempted unnecessarily. > > > > If I am not mistaken, the code works as follows: > > > > > > for slave in slaves: > > while SchedulingFilter.filter is still yielding vetos: > > add preemptable task of slave to list toPreemptTasks > > > > if toPreemptTasks has some tasks: > > preempt > > return > > > > > > SchedulingFilter is checking for available resources and constraints. > > Unfortunately, it seems the preemptor cannot handle constraints: It may > > drain an entire slave trying to make room for a new task. However, if > > this task has a constraint which prevents it from being scheduled on > > this slave at all, then the other tasks are preempted unnecessarily. > > > > Is my analysis correct here? > > > > Best Regards, > > Stephan > > > > > > > > > > > > >
