> Between 2 operators, if one configures thread/container local and > anti-affinity as well, which one will take affect?
The DAG validation step should error out in this case. +1 on suggestion by Chinmay to name it "Affinity Rules" than anti-affinity. We are just extending our container allocation scheme to support containers not to be allocated together. Regards, Sandeep On Fri, Jan 22, 2016 at 1:43 PM, Chinmay Kolhatkar <[email protected]> wrote: > Hi Isha, > > Couple of points: > 1. About the interface to configuring anti-affinity, as per suggestion > above there are 2 different way to configure locality and anti-affinity: > i.e. dag.setAttribute - for anti-affinity & > dag.addStream(...).setLocality for locality. > > Between 2 operators, if one configures thread/container local and > anti-affinity as well, which one will take affect? > > 2. Consider there could be such confusion as above, would it make sense to > have a single API which takes care of both anti-affinity and locality. This > way, one is configurable. > > 3. This point is coming from how VM affinity is configured in vSphere. > The VMs are configured affinity are called as "affinity rules" and not > "anti-affinity rules". Ultimately idea is to allocate processing to nodes. > Via "VM-VM affinity rules", anti-affinity is also configured. But there is > a single set of rule definition for both affinity (similar to locality in > our case) and anti-affinity. > Would it be a better approach for configuring locality rules and > anti-affinity rules in a single rule and call it "affinity rule". > > Thanks, > Chinmay. > > > On Fri, Jan 22, 2016 at 12:24 PM, Yogi Devendra <[email protected]> > wrote: > > > @Isha > > > > I understand that anti-affinity across application is not > straight-forward. > > It would be OK even if we do not have it in iteration 1. > > > > But, for attributes syntax; I still think that Java object should be > > avoided as they will be hard to configure from dt-site.xml or other > config > > files. > > Other suggestion for this could be JSON representation of String array: > > ["O2", "O3"]. (If operator names has some special characters like " or [ > > or , those will be escaped in the JSON representation.) > > Not sure if others agree on this; but attribute syntax should be > finalized > > in iteration 1 to avoid backward compatibility issues later. > > > > ~ Yogi > > > > On 22 January 2016 at 00:43, Thomas Weise <[email protected]> > wrote: > > > > > 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. > > > > > >> > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > >
