Node based requests is the best approach - if it works :-) Blacklisting will require to allocate the containers sequentially. It will work, but slow down application startup, especially for larger topologies.
On Thu, Jan 21, 2016 at 10:42 AM, Isha Arkatkar <[email protected]> wrote: > Hi, > > Should we consider the node based requests if it works with Capacity > Scheduler or avoid 2b approach altogether? I checked that node requests do > not work with fair scheduler on CDH cluster. Yarn does not return any > container if hostname is given in the container request. I am trying to > setup a small virtual hortonworks cluster to check the this behavior on > that. > YARN-2027 <https://issues.apache.org/jira/browse/YARN-2027> mentioned that > container requests are not honored in capacity scheduler too. But I am not > sure if it is because of distro dependent issue. Please share insights. > > @Vlad, Adding support for regular expression sounds good. We could > translate to list of operator names internally based on regex. > > @Yogi, I went with a list of strings for attribute because "O2, O3" could > be a valid single operator name too :) > I am not sure of ways to implement anti-affinity across application. Though > something to consider for later iteration. > > Thanks, > Isha > > On Wed, Jan 20, 2016 at 8:59 PM, Thomas Weise <[email protected]> > wrote: > > > https://issues.apache.org/jira/browse/SLIDER-82 > > > > > > On Wed, Jan 20, 2016 at 8:56 PM, Thomas Weise <[email protected]> > > wrote: > > > > > The point was that containers are taken away from other apps that may > > have > > > to discard work etc. It's not good style to claim resources and not use > > > them eventually :-) > > > > > > For this feature it is necessary to look at the scheduler > > > capabilities/semantics and limitations. For example, don't bet > > exclusively > > > on node requests if the goal is for it to work with FairScheduler. > > > > > > Also look at Slider, which just recently added support for > anti-affinity > > > (using node requests). When you run it on the CDH cluster, it probably > > > won't work... > > > > > > > > > On Wed, Jan 20, 2016 at 3:19 PM, Pramod Immaneni < > [email protected] > > > > > > wrote: > > > > > >> Once released won't the containers be available again in the pool. > This > > >> would only be optional and not mandatory. > > >> > > >> Thanks > > >> > > >> On Tue, Jan 19, 2016 at 2:02 PM, Thomas Weise <[email protected] > > > > >> wrote: > > >> > > >> > How about also supporting a minor variation of it as an option > > >> > > where it greedily gets the total number of containers and discards > > >> ones > > >> > it > > >> > > can't use and repeats the process for the remaining till > everything > > >> has > > >> > > been allocated. > > >> > > > >> > > > >> > This is problematic as with resource preemption these containers > will > > be > > >> > potentially taken away from other applications and then thrown away. > > >> > > > >> > > > >> > > > >> > > > >> > > Also does it make sense to support anti-cluster affinity? > > >> > > > > >> > > Thanks > > >> > > > > >> > > On Tue, Jan 19, 2016 at 1:21 PM, Isha Arkatkar < > > [email protected]> > > >> > > wrote: > > >> > > > > >> > > > Hi all, > > >> > > > > > >> > > > We want add support for Anti-affinity in Apex to allow > > >> applications > > >> > to > > >> > > > launch specific physical operators on different > nodes(APEXCORE-10 > > >> > > > <https://issues.apache.org/jira/browse/APEXCORE-10>). Want to > > >> request > > >> > > your > > >> > > > suggestions/ideas for the same! > > >> > > > > > >> > > > The reasons for using anti-affinity in operators could be: to > > >> ensure > > >> > > > reliability, for performance reasons (such as application may > not > > >> want > > >> > 2 > > >> > > > i/o intensive operators to land on the same node to improve > > >> > performance) > > >> > > or > > >> > > > for some application specific constraints(for example, 2 > > partitions > > >> > > cannot > > >> > > > be run on the same node since they use same port number). This > is > > >> the > > >> > > > general rationale for adding Anti-affinity support. > > >> > > > > > >> > > > Since, Yarn does not support anti-affinity yet (YARN-1042 > > >> > > > <https://issues.apache.org/jira/browse/YARN-1042>), we need to > > >> > implement > > >> > > > the logic in AM. Wanted to get your views on following aspects > for > > >> this > > >> > > > implementation: > > >> > > > > > >> > > > *1. How to specify anti-affinity for physical > operators/partitions > > >> in > > >> > > > application:* > > >> > > > One way for this is to have an attribute for setting > > >> anti-affinity > > >> > at > > >> > > > the logical operator context. And an operator can set this > > attribute > > >> > with > > >> > > > list of operator names which should not be collocated. > > >> > > > Consider dag with 3 operators: > > >> > > > TestOperator o1 = dag.addOperator("O1", new > TestOperator()); > > >> > > > TestOperator o2 = dag.addOperator("O2", new > TestOperator()); > > >> > > > TestOperator o3 = dag.addOperator("O3", new > TestOperator()); > > >> > > > > > >> > > > To set anti-affinity for O1 operator: > > >> > > > dag.setAttribute(o1, OperatorContext.ANTI_AFFINITY, new > > >> > > > ArrayList<String>(Arrays.asList("O2", "O3"))); > > >> > > > This would mean O1 should not be allocated on nodes > > containing > > >> > > > operators O2 and O3. This applies to all allocated partitions of > > O1, > > >> > O2, > > >> > > > O3. > > >> > > > > > >> > > > Also, if same operator name is part of anti-affinity list, it > > >> means > > >> > > > partitions of the operator should not be allocated on the same > > node. > > >> > > > example: > > >> > > > dag.setAttribute(o2, OperatorContext.ANTI_AFFINITY, new > > >> > > > ArrayList<String>(Arrays.asList("O2"))); > > >> > > > This indicates anti-affinity between all partitions of O2. > > i.e. > > >> all > > >> > > > partitions of O2 should be launched on different nodes. > > >> > > > > > >> > > > Based on the anti-affinity attribute specified for logical > > >> operator, > > >> > > > during physical plan creation, we can add this list to each > > >> > PTContainer. > > >> > > > This in turn will be available for Stram for sending container > > >> requests > > >> > > > accordingly. > > >> > > > > > >> > > > Please suggest if there is a better way to express this > intent. > > >> > > > > > >> > > > *2. How to implement anti-affinity in AM* > > >> > > > There are 2 ways we can implement this: > > >> > > > * a. Blacklisting of nodes: *We can group the physical > container > > >> > > requests > > >> > > > based on anti-affinity requirements and send allocation requests > > for > > >> > > > containers in groups. After first group is done, blacklist the > > nodes > > >> > > before > > >> > > > sending second group of container requests. This will ensure > that > > >> the > > >> > > > containers with anti-affinity requirements will be allocated on > > >> > > different > > >> > > > nodes. > > >> > > > * b. Node specific container request: *Explore and create a > map > > of > > >> > > nodes > > >> > > > present in the cluster and send allocation request for container > > on > > >> a > > >> > > > specific node, honoring anti-affinity. There are couple of open > > Yarn > > >> > > Jiras > > >> > > > for node specific container requests: YARN-1412 > > >> > > > <https://issues.apache.org/jira/browse/YARN-1412>, YARN-2027 > > >> > > > <https://issues.apache.org/jira/browse/YARN-2027>. So, need to > > >> check > > >> > if > > >> > > > this is a plausible approach. > > >> > > > > > >> > > > *3. Strict Vs Relaxed anti-affinity* > > >> > > > Depending on cluster resources availability, it may not be > > >> possible > > >> > to > > >> > > > honor all anti-affinity requirements specified. > > >> > > > *Strict Anti-affinity:* AM will keep trying to allocate > containers > > >> as > > >> > per > > >> > > > anti-affinity requirements indefinitely. This behavior will be > > >> similar > > >> > to > > >> > > > how an application shows in ACCEPTED state, till resources are > > >> > available > > >> > > to > > >> > > > launch in cluster. > > >> > > > *Relaxed Anti-affinity:* AM will drop the anti-affinity > constraint > > >> > after > > >> > > a > > >> > > > certain timeout. > > >> > > > > > >> > > > We need a way to set this attribute through application. (Either > > in > > >> > > > operator context or in DAGContext for application wide setting.) > > >> > > > > > >> > > > *4. How do we unit test this feature* > > >> > > > We could use Mockito for mocking Yarn behaviors and test only > AM > > >> > > > implementation, since it may not be easy to simulate some > > scenarios > > >> > > > manually in cluster. Please suggest if there are better ways to > > test > > >> > > this. > > >> > > > > > >> > > > Please suggest improvements or any other ideas on all of the > > above. > > >> > > > > > >> > > > Thanks! > > >> > > > Isha > > >> > > > > > >> > > > P.S. Sorry for long email. Please let me know if I should start > > >> > separate > > >> > > > threads for any of the above points. > > >> > > > > > >> > > > > >> > > > >> > > > > > > > > >
