Jie, that sounds good. I think between the cgroups guarantees and MESOS-1417 we should be OK.
I think with cgroups (or pid namespaces in the future), when the executor > dies, all processes belong to the cgroup (or pid namespace) will killed by > the slave. Another point: Strictly speaking, the top pid of the executor's process tree isn't necessarily the executor itself but could be a /bin/sh process that launched it. What I noticed (when using process isolation for testing) is that when that sh process is killed, the executor process continues to live but Mesos reports task lost for tasks associated with that executor. I am taking your above statement to imply that the exiting of the sh process in this case also kills all processes of the cgroup before reporting task lost status. Thank you. On Tue, Jun 3, 2014 at 7:17 PM, Jie Yu <[email protected]> wrote: > Sharma, > > While it is a good practice for the task processes to exit when their >> executor dies, I am not sure that can be guaranteed. > > > I think with cgroups (or pid namespaces in the future), when the executor > dies, all processes belong to the cgroup (or pid namespace) will killed by > the slave. > > Especially problematic for ports. Not as much for CPU and memory. > > > Yeah, we are addressing this issue right now. I think ticket MESOS-1417 > keeps track of this process. More specifically, we should not tell the > master a task has FINISHED/LOST/FAILED/KILLED until its resources have been > freed. > > - Jie > > > On Tue, Jun 3, 2014 at 6:07 PM, Sharma Podila <[email protected]> wrote: > >> No, I haven't talked to either of them. Would be great to hear their >> thoughts on this. Thanks for including them. >> >> Is container cleanup specific to cgroups? Or, would other containers, say >> Docker, also have similar clean up behavior? >> >> >> On Tue, Jun 3, 2014 at 5:44 PM, Vinod Kone <[email protected]> wrote: >> >>> +Jie,Ian >>> >>> Not sure if you've talked to Ian Downes and/or Jie Yu regarding this but >>> they were discussing the same issue (offline) today. >>> >>> Just to be sure, if you are using cgroups, the mesos slave will cleanup >>> the container (and all its processes) when an executor exits. Now there is >>> definitely a race here, mesos might release the resource to framework >>> before the container is destroyed. We'll try to fix that really soon. I'll >>> let Jie/Ian chime in regarding fixes/tickets. >>> >>> >>> On Tue, Jun 3, 2014 at 4:25 PM, Sharma Podila <[email protected]> >>> wrote: >>> >>>> When a framework executor terminates, Mesos sends TASK_LOST status >>>> updates for tasks that were running. However, if a task had processes that >>>> do not terminate when the executor dies, then we have a problem since Mesos >>>> considers the slave resources assigned to those tasks as released. Where >>>> as, the task processes are running without releasing those resources. >>>> >>>> While it is a good practice for the task processes to exit when their >>>> executor dies, I am not sure that can be guaranteed. I am wondering how >>>> others are dealing with such "illegal" processes - that is, processes that >>>> once belonged to Mesos run tasks but not anymore. >>>> >>>> Conceivably, a per-slave reaper/GC process can periodically scan the >>>> slave's process tree to ensure all processes are 'legal'. Assuming that >>>> such a reaper exists (and could be tricky in a multi-framework environment) >>>> on the slave and is not risky in killing illegal processes, there is still >>>> the time window left until the reaper completes its next clean up routine. >>>> In the mean time, new tasks can land and fail trying to use a resource that >>>> was assumed to be free by Mesos. Especially problematic for ports. Not as >>>> much for CPU and memory. >>>> >>>> Would love to hear thoughts on how you are handling this scenario. >>>> >>>> >>> >> >
