Hey Chinmay, I certainly agree on common set of rules for configuring affinity! Well put by a concrete example. :) Only thing I would like to point is: affinity of operators should not cover thread and container locality. Since this is only applicable when operators are connected by stream. So, it makes sense to have it on Stream rather than in common configuration.
And yes, DAG.validate should only check for REQUIRED or STRICT policy. We can agree on one of the terminologies STRICT/RELAXED or REQUIRED/PREFERRED. Thanks! Isha On Fri, Jan 22, 2016 at 8:38 PM, Chinmay Kolhatkar <[email protected]> wrote: > Hi Isha, Bhupesh, > > When I suggested singe affinity rule, I was mainly talking about "how to" > of configuration and not of implementation. > > I see locality is in a way suggesting an affinity of operators. They're > close terminologies. > By configuring a locality on stream, we're also, in a way, defining > affinity of operators. > > Until now, only locality was there and hence was straight forward in > configuration for user. > Tomorrow, when anti-affinity configuration comes up, one might get confused > on how to best use both locality & anti-affinity. > Hence suggested to make both (locality/affinity & anti-affinity) as a part > of single configuration. > > Suggestion is to have a more commonly adopted configuration which admins > and developer's are familiar with. > Again referring to vShere Hypervisor's affinity rules. I think they have a > single configuration which does both. > > Having said that, here is a quick suggestion on how both can be achieved in > a single configuration: > > CATEGORY TYPE POLICY ENTITIES > Affinity THREAD REQUIRED O1, O2 //Meaning > Operator1 & Operator2 should be thread local > Affinity NODE PREFERRED O3, O4 //Meaning O3 & > O4 are preferred to be in node local > AntiAffinity NODE REQUIRED O1, O4 //Meaning O1 & > O4 should not be on same node. > AntiAffinity RACK PREFERRED O2, O4 //Meaning O2 & > O4 are preferred not to be on same rack. > > > Linux setting affinity of CPUs for threads is another way of configuration > we can take a look at. > > Learning from these commonly adopted configuration pattern, we should come > up with best configuration suitable for distributed environment. > Idea here is to not have our own configuration and give something new to > the users. Otherwise such an important concept might quickly get lost. > > Regarding the DAG.validate I think we would need to add some new stuff to > take care of anti-affinity. > Plus, anti-affinity/affinity should be validated at DAG.validate only for > the ones which are required. > For preferred policies, validation in logical plan might be a early check. > > Thanks, > Chinmay. > > > > On Sat, Jan 23, 2016 at 3:15 AM, Isha Arkatkar <[email protected]> > wrote: > > > Hi, > > > > Thanks for inputs! I like the idea of having single set of > > (anti?)affinity rules at dag context level. > > There could still be conflicts based on Locality for Streams or Node > > locality attribute set for operators. But as Sandeep suggested, I also > > think Dag.validate should fail in case of contradicting constraints. > > > > We currently do not have 'affinity' among non stream operators, as > Bhupesh > > pointed out. It is somewhat achievable by requesting node locality for > > operators (Assuming node requests work as expected). But should we > consider > > adding affinity specifications support as well along with anti-affinity? > > > > Regarding specification of attributes from dt-site.xml. We can go with > > Json like string or even xml representation for complex objects. What is > > our current behavior for setting Java object properties through XML? We > can > > follow the same for this as well. > > > > As for precedence or ability to satisfy constraints: Right now in > normal > > scenario, if resources are not available for allocating containers, we > keep > > sending to request till all are obtained. Likewise, in case of strict > > anti-affinity policy, we should keep the application in ACCEPTED state > till > > the anti-affinity constraint is satisfied. For relaxed policy, we can > > decide timeout for relaxing the anti-affinity rule. Please note this > > applies only when we have non-contradicting rules. > > > > Thanks! > > Isha > > > > On Fri, Jan 22, 2016 at 5:30 AM, Bhupesh Chawda <[email protected] > > > > wrote: > > > > > I agree on having a single set of rules for the affinity as well as > > > anti-affinity of operators / partitions on containers. > > > > > > However, I noted the following points: > > > > > > 1. AFAIK, we do not support affinity (locality) in a general sense. > > The > > > affinity is only for a stream, not for *any* two operators. So, we > > > should also look at the general case and see how it can be > supported, > > if > > > there are valid use cases. > > > 2. Coming to anti-affinity, we cannot type cast it as a type of > > affinity > > > rule. Saying "two operators must be on the same container" is very > > > different from saying "these two operators must not be on the same > > > container". In this case, the second one is a much more relaxed rule > > as > > > compared to the first one. > > > 3. Once we have this generic set of rules, there must be a > > > "satisfiability" test run before requesting YARN for containers. If > > the > > > request is not satisfiable, then there is no point asking YARN to > > > allocate > > > containers in this manner. In case it is not satisfiable, we must > also > > > have > > > a default order in which the rules can be "relaxed" and the request > be > > > made > > > satisfiable. For example, some very strict rules may be ignored, or > > made > > > less constraining ( for example "on the same container" => "on the > > same > > > node"). > > > > > > Thanks. > > > > > > -Bhupesh > > > > > > On Fri, Jan 22, 2016 at 2:54 PM, Aniruddha Thombare < > > > [email protected]> wrote: > > > > > > > +1 On Chinmay's suggestion about having single set of affinity rules. > > > > > > > > > > > > Thanks, > > > > > > > > > > > > Aniruddha > > > > > > > > On Fri, Jan 22, 2016 at 1:57 PM, Sandeep Deshmukh < > > > [email protected] > > > > > > > > > wrote: > > > > > > > > > > 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. > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
