Wrote a design draft for resource-related annotations. Please have a look: https://docs.google.com/document/d/1phExeGD1gdDI9M8LK4ZG57UGa7dswpB8Aj6jxWj4uQk/edit?usp=sharing
Cheers, Mirac On 2020/11/26 20:20:09, Mirac Vuslat Basaran <mir...@google.com> wrote: > Created a PR without unit tests at https://github.com/apache/beam/pull/13434. > Please have a look. > > Thanks, > Mirac > > > On 2020/11/25 18:50:19, Robert Burke <rob...@frantil.com> wrote: > > Hmmm. Fair. I'm mostly concerned about the pathological case where we end > > up with a distinct Environment per transform, but there are likely > > practical cases where that's reasonable (High mem to GPU to TPU, to ARM....) > > > > On Wed, Nov 25, 2020, 10:42 AM Robert Bradshaw <rober...@google.com> wrote: > > > > > I'd like to continue the discussion *and* see an implementation for > > > the part we've settled on. I was asking why not have "every distinct > > > physical concern means a distinct environment?" > > > > > > On Wed, Nov 25, 2020 at 10:38 AM Robert Burke <rob...@frantil.com> wrote: > > > > > > > > Mostly because perfect is the enemy of good enough. We have a proposal, > > > we have clear boundaries for it. It's fine if the discussion continues, > > > but > > > I see no evidence of concerns that should prevent starting an > > > implementation, because it seems we'll need both anyway. > > > > > > > > On Wed, Nov 25, 2020, 10:25 AM Robert Bradshaw <rober...@google.com> > > > wrote: > > > >> > > > >> On Wed, Nov 25, 2020 at 10:15 AM Robert Burke <rob...@frantil.com> > > > wrote: > > > >> > > > > >> > It sounds like we've come to the position that non-correctness > > > affecting Ptransform Annotations are valuable at both leaf and composite > > > levels, and don't remove the potential need for a similar feature on > > > Environments, to handle physical concerns equirements for worker processes > > > to have (such as Ram, CPU, or GPU requirements.) > > > >> > > > > >> > Kenn, it's not clear what part of the solution (an annotation field > > > on the Ptransform proto message) would need to change to satisfy your > > > scope > > > concern, beyond documenting unambiguously that these may not be used for > > > physical concerns or things that affect correctness. > > > >> > > > >> I'll let Kenn answer as well, but from my point of view, explicitly > > > >> having somewhere better to put these things would help. > > > >> > > > >> > I'm also unclear your scope concern not matching, given the above. > > > Your first paragraph reads very supportive of logical annotations on > > > Ptransforms, and that matches 1-1 with the current proposed solution. Can > > > you clarify your concern? > > > >> > > > > >> > I don't wish to scope creep on the physical requirements issue at > > > this time. It seems we are agreed they should end up on environments, but > > > I'm not seeing proposals on the right way to execute them at this > > > time.They > > > seem to be a fruitful topic of discussion, in particular > > > unifying/consolidating them for efficient use of resources. I don't think > > > we want to end up in a state where every distinct physical concern means a > > > distinct environment. > > > >> > > > >> Why not? Assuming, of course, that runners are free to merge > > > >> environments (merging those resource hints they understand and are > > > >> otherwise compatible, and discarding those they don't) for efficient > > > >> execution. > > > >> > > > >> > I for one am ready to see a PR. > > > >> > > > >> +1 > > > >> > > > >> > On Mon, Nov 23, 2020, 6:02 PM Kenneth Knowles <k...@apache.org> > > > wrote: > > > >> >> > > > >> >> > > > >> >> > > > >> >> On Mon, Nov 23, 2020 at 3:04 PM Robert Bradshaw > > > >> >> <rober...@google.com> > > > wrote: > > > >> >>> > > > >> >>> On Fri, Nov 20, 2020 at 11:08 AM Mirac Vuslat Basaran < > > > mir...@google.com> wrote: > > > >> >>> > > > > >> >>> > Thanks everyone so much for their input and for the insightful > > > discussion. > > > >> >>> > > > > >> >>> > Not being knowledgeable about Beam's internals, I have to say I > > > am a bit lost on the PTransform vs. environment discussion. > > > >> >>> > > > > >> >>> > I do agree with Burke's notion that merge rules are very > > > annotation dependent, I don't think we can find a one-size-fits-all > > > solution for that. So this might be actually be an argument in favour of > > > having annotations on PTransforms, since it avoids the conflation with > > > environments. > > > >> >>> > > > > >> >>> > Also in general, I feel that having annotations per single > > > transform (rather than composite) and on PTransforms could lead to a > > > simpler design. > > > >> >>> > > > >> >>> If we want to use these for privacy, I don't see how attaching them > > > to > > > >> >>> leaf transforms alone could work. (Even CombinePerKey is a > > > composite.) > > > >> >>> > > > >> >>> > Seeing as there are valuable arguments in favour of both > > > (PTransform and environments) with no clear(?) "best solution", I would > > > propose moving forward with the initial (PTransform) design to ship the > > > feature and unblock teams asking for it. If it turns out that there was > > > indeed a need to have annotations in environments, we could always > > > refactor > > > it. > > > >> >>> > > > >> >>> I have yet to see any arguments that resource-level hints, such as > > > >> >>> memory or GPU, don't better belong on the environment. But moving > > > >> >>> forward on PTransform-level ones for logical statements like > > > >> >>> privacy > > > >> >>> declarations makes sense. > > > >> >> > > > >> >> > > > >> >> Exactly this. Properties of transforms make sense. The properties > > > may hold only of the whole subgraph. Even something as simple as > > > "preserves > > > keys". This is analogous (but converse) to requirements like "requires > > > sorted input" which were explicitly excluded from the scope, which was > > > about hardware environment for execution. > > > >> >> > > > >> >> The proposed scope and the proposed solution do not match and need > > > to be reconciled. > > > >> >> > > > >> >> Kenn > > > >> >> > > > >> >>> > On 2020/11/17 19:07:22, Robert Bradshaw <rober...@google.com> > > > wrote: > > > >> >>> > > So far we have two distinct usecases for annotations: resource > > > hints > > > >> >>> > > and privacy directives, and I've been trying to figure out how > > > to > > > >> >>> > > reconcile them, but they seem to have very different > > > characteristics. > > > >> >>> > > (It would be nice to come up with other uses as well to see if > > > we're > > > >> >>> > > really coming up with a generally useful mode--I think display > > > data > > > >> >>> > > could fit into this as a new kind of annotation rather than > > > being a > > > >> >>> > > top-level property, and it could make sense on both leaf and > > > composite > > > >> >>> > > transforms.) > > > >> >>> > > > > > >> >>> > > To me, resource hints like GPU are inextricably tied to the > > > >> >>> > > environment. A transform tagged with GPU should reference a Fn > > > that > > > >> >>> > > invokes GPU-accelerated code that lives in a particular > > > environment. > > > >> >>> > > Something like high-mem is a bit squishier. Some DoFns take a > > > lot of > > > >> >>> > > memory, but on the other hand one could imagine labeling a > > > CoGBK as > > > >> >>> > > high-mem due to knowing that, in this particular usage, there > > > will be > > > >> >>> > > lots of values with the same key. Ideally runners would be > > > intelligent > > > >> >>> > > enough to automatically learn memory usage, but even in this > > > case it > > > >> >>> > > may be a good hint to try and learn the requirements for DoFn A > > > and > > > >> >>> > > DoFn B separately (which is difficult if they are always > > > colocated, > > > >> >>> > > but valuable if, e.g. A takes a huge amount of memory and B > > > takes a > > > >> >>> > > huge amount of wall time). > > > >> >>> > > > > > >> >>> > > Note that tying things to the environment does not preclude > > > using them > > > >> >>> > > in non-portable runners as they'll still have an SDK-level > > > >> >>> > > representation (though I don't think we should have an explicit > > > goal > > > >> >>> > > of feature parity for non-portable runners, e.g. multi-language > > > isn't > > > >> >>> > > happening, and hope that non-portable runners go away soon > > > anyway). > > > >> >>> > > > > > >> >>> > > Now let's consider privacy annotations. To make things very > > > concrete, > > > >> >>> > > imagine a transform AverageSpendPerZipCode which takes as input > > > (user, > > > >> >>> > > zip, spend), all users unique, and returns (zip, avg(spend)). > > > >> >>> > > In > > > >> >>> > > Python, this is GroupBy('zip').aggregate_field('spend', > > > >> >>> > > MeanCombineFn()). This is not very privacy preserving to those > > > users > > > >> >>> > > who are the only (or one of a few) in a zip code. So we could > > > define a > > > >> >>> > > transform PrivacyPreservingAverageSpendPerZipCode as > > > >> >>> > > > > > >> >>> > > @ptransform_fn > > > >> >>> > > def PrivacyPreservingAverageSpendPerZipCode(spend_per_user, > > > threshold) > > > >> >>> > > counts_per_zip = spend_per_user | > > > >> >>> > > GroupBy('zip').aggregate_field('user', CountCombineFn()) > > > >> >>> > > spend_per_zip = spend_per_user | > > > >> >>> > > GroupBy('zip').aggregate_field('spend', MeanCombineFn()) > > > >> >>> > > filtered = spend_per_zip | beam.Filter( > > > >> >>> > > lambda x, counts: counts[x.zip] > threshold, > > > >> >>> > > counts=AsMap(counts_per_zip)) > > > >> >>> > > return filtered > > > >> >>> > > > > > >> >>> > > We now have a composite that has privacy preserving properties > > > (i.e. > > > >> >>> > > the input may be quite sensitive, but the output is not, > > > depending on > > > >> >>> > > the value of threshold). What is interesting here is that it is > > > only > > > >> >>> > > the composite that has this property--no individual > > > sub-transform is > > > >> >>> > > itself privacy preserving. Furthermore, an optimizer may notice > > > we're > > > >> >>> > > doing aggregation on the same key twice and rewrite this using > > > >> >>> > > (logically) > > > >> >>> > > > > > >> >>> > > GroupBy('zip').aggregate_field('user', > > > >> >>> > > CountCombineFn()).aggregate_field('spend', MeanCombineFn()) > > > >> >>> > > > > > >> >>> > > and then applying the filter, which is semantically equivalent > > > and > > > >> >>> > > satisfies the privacy annotations (and notably that does not > > > even > > > >> >>> > > require the optimizer to interpret the annotations, just pass > > > them > > > >> >>> > > on). To me, this implies that these annotations belong on the > > > >> >>> > > composites, and *not* on the leaf nodes (where they would be > > > >> >>> > > incorrect). > > > >> >>> > > > > > >> >>> > > I'll leave aside most questions of API until we figure out the > > > model > > > >> >>> > > semantics, but wanted to throw one possible idea out (though I > > > am > > > >> >>> > > ambivalent about it). Instead of attaching things to > > > transforms, we > > > >> >>> > > can just wrap transforms in composites that have no role other > > > than > > > >> >>> > > declaring information about their contents. E.g. we could have > > > >> >>> > > a > > > >> >>> > > composite transform whose payload is simply an assertion of the > > > >> >>> > > privacy (or resource?) properties of its inner structure. This > > > would > > > >> >>> > > be just as expressive as adding new properties to transforms > > > >> >>> > > themselves (but would add an extra level of nesting, and make > > > >> >>> > > respecting the precice nesting more important). > > > >> >>> > > > > > >> >>> > > On Tue, Nov 17, 2020 at 8:12 AM Robert Burke < > > > rob...@frantil.com> wrote: > > > >> >>> > > > > > > >> >>> > > > +1 to discussing PCollection annotations on a separate > > > thread. It would be confusing to mix them up. > > > >> >>> > > > > > > >> >>> > > > ----------- > > > >> >>> > > > > > > >> >>> > > > The question around conflicts is interesting, but confusing > > > to me. I don't think they exist in general. I keep coming back around to > > > that it depends on the annotation and the purpose of composites. > > > Optionality saves us here too. > > > >> >>> > > > > > > >> >>> > > > Composites are nothing without their internal hypergraph > > > structure. Eventually it comes down to executing the leaf nodes. The > > > alternative to executing the leaf nodes is when the composite represents a > > > known transform and is replaced by the runner on submission time. Lets > > > look at each. > > > >> >>> > > > > > > >> >>> > > > If there's a property that only exists on the leaf nodes, > > > then it's not possible to bubble up that property to the composite in all > > > cases. Afterall, it's not necessarily the case that a privacy preserving > > > transform maintains the property for all output edges as not all such > > > edges > > > pass through the preserving transform. > > > >> >>> > > > > > > >> >>> > > > On the other hand, with memory or gpu recommendations, that > > > might set a low bar on the composite level. > > > >> >>> > > > > > > >> >>> > > > But, composites (any transform really) can be runner > > > replaced. I think it's fair to say that a runner replaced composite is not > > > beholden to the annotations of the original leaf transforms, especially > > > around physical requirements. The implementations are different. If a > > > known > > > composite at the composite level requires GPUs and it's known replacement > > > doesn't, I'd posit that replacement was a choice the runner made since it > > > can't provision machines with GPUs. > > > >> >>> > > > > > > >> >>> > > > But, crucially around privacy annotated transforms, a runner > > > likely shouldn't replace a given subgraph that contains a privacy > > > annotationed transform unless the replacements provide the same level of > > > privacy. However, such replacements only happens with well known > > > transforms > > > with known properties anyway, so this can serve as an additional layer of > > > validation for a runner aware of the properties. > > > >> >>> > > > > > > >> >>> > > > This brings me back to my position: that the notion of > > > conflicts is very annotation dependant, and that defining them as optional > > > is the most important feature to avoid issues. Conflicts don't exist as an > > > inherent property of annotations on ptransform of the hypergraph > > > structure. > > > Am i wrong? No one has come up with an actual example of a conflict as far > > > as i understand the thread. > > > >> >>> > > > > > > >> >>> > > > Even Reuven's original question is more about whether the > > > runner is forced to look at leaf bodes rather than only looking at the > > > composite. Assuming the composite isn't replaced, the runner needs to look > > > at the leaf nodes regardless. And as discussed above there's no > > > generalized > > > semantics that fit for all kinds of annotations, once replacements are > > > also > > > considered. > > > >> >>> > > > > > > >> >>> > > > On Tue, Nov 17, 2020, 6:35 AM Ismaël Mejía > > > >> >>> > > > <ieme...@gmail.com> > > > wrote: > > > >> >>> > > >> > > > >> >>> > > >> +1 Nice to see there is finally interest on this. > > > Annotations for > > > >> >>> > > >> PTransforms make total sense! > > > >> >>> > > >> > > > >> >>> > > >> The semantics should be strictly optional for runners and > > > correct > > > >> >>> > > >> execution should not be affected by lack of support of any > > > annotation. > > > >> >>> > > >> We should however keep the set of annotations small. > > > >> >>> > > >> > > > >> >>> > > >> > PTransforms are hierarchical - namely a PTransform > > > contains other PTransforms, and so on. Is the runner expected to resolve > > > all annotations down to leaf nodes? What happens if that results in > > > conflicting annotations? > > > >> >>> > > >> > > > >> >>> > > >> +1 to this question, This needs to be detailed. > > > >> >>> > > >> > > > >> >>> > > >> I am curious about how the end user APIs of this will look > > > maybe in > > > >> >>> > > >> Java or Python, just an extra method to inject a Map or via > > > Java > > > >> >>> > > >> annotations/Python decorators? > > > >> >>> > > >> > > > >> >>> > > >> We might prefer not to mix the concepts of annotations and > > > >> >>> > > >> environments because this will limit the scope of > > > annotations. > > > >> >>> > > >> Annotations are different from environments because they > > > serve a more > > > >> >>> > > >> general idea: to express an intention and it is up to the > > > runner to > > > >> >>> > > >> choose the strategy to accomplish this, for example in the > > > GPU > > > >> >>> > > >> assignation case it could be to rewrite resource allocation > > > via > > > >> >>> > > >> Environments but it could also just delegate this to a > > > resource > > > >> >>> > > >> manager which is what we could do for example for GPU (or > > > data > > > >> >>> > > >> locality) cases on the Spark/Flink classic runners. If we > > > tie this to > > > >> >>> > > >> environments we will leave classic runners out of the loop > > > for no > > > >> >>> > > >> major reason and also not cover use cases not related to > > > resource > > > >> >>> > > >> allocation. > > > >> >>> > > >> > > > >> >>> > > >> I do not understand the use case to justify PCollection > > > annotations > > > >> >>> > > >> but to not mix this thread with them, would you be > > > interested to > > > >> >>> > > >> elaborate more about them in a different thread Jan? > > > >> >>> > > >> > > > >> >>> > > >> On Tue, Nov 17, 2020 at 2:28 AM Robert Bradshaw < > > > rober...@google.com> wrote: > > > >> >>> > > >> > > > > >> >>> > > >> > I agree things like GPU, high-mem, etc. belong to the > > > environment. If > > > >> >>> > > >> > annotations are truly advisory, one can imagine merging > > > environments > > > >> >>> > > >> > by taking the union of annotations and still producing a > > > correct > > > >> >>> > > >> > pipeline. (This would mean that annotations would have to > > > be a > > > >> >>> > > >> > multi-map...) > > > >> >>> > > >> > > > > >> >>> > > >> > On the other hand, this doesn't seem to handle the case of > > > privacy > > > >> >>> > > >> > analysis, which could apply to composites without applying > > > to any > > > >> >>> > > >> > individual component, and don't really make sense as part > > > of a > > > >> >>> > > >> > fusion/execution story. > > > >> >>> > > >> > > > > >> >>> > > >> > On Mon, Nov 16, 2020 at 4:00 PM Robert Burke < > > > rob...@frantil.com> wrote: > > > >> >>> > > >> > > > > > >> >>> > > >> > > That's good historical context. > > > >> >>> > > >> > > > > > >> >>> > > >> > > But then we'd still need to codify the annotation would > > > need to be optional, and not affect correctness. > > > >> >>> > > >> > > > > > >> >>> > > >> > > Conflicts become easier to manage, (as environments with > > > conflicting annotations simply don't get merged, and stay as distinct > > > environments) but are still notionally annotation dependant. Do most > > > runners handle environments so individually though? > > > >> >>> > > >> > > > > > >> >>> > > >> > > Reuven's question is a good one though. For the Go SDK, > > > and the proposed implementation i saw, they only applied to leaf nodes. > > > This is an artifact of how the Go SDK handles composites. Nothing stops it > > > from being implemented on the composites Go has, but it didn't make sense > > > otherwise. AFAICT Composites are generally for organizational convenience > > > and not for functional aspects. Is this wrong? Afterall, does it make > > > sense > > > for environments to be on leaves and composites either? It's the same > > > issue > > > there. > > > >> >>> > > >> > > > > > >> >>> > > >> > > > > > >> >>> > > >> > > On Mon, Nov 16, 2020, 3:45 PM Kenneth Knowles < > > > k...@apache.org> wrote: > > > >> >>> > > >> > >> > > > >> >>> > > >> > >> I am +1 to the proposal but believe it should be moved > > > to the Environment. I could be convinced otherwise, but would want to > > > really understand the details. > > > >> >>> > > >> > >> > > > >> >>> > > >> > >> I think we haven't done a great job communicating the > > > purpose of the Environment proto. It was explicitly created for this > > > purpose. > > > >> >>> > > >> > >> > > > >> >>> > > >> > >> 1. It tells the runner things it needs to know to > > > interpret the DoFn (or other UDF). So these are the existing proto fields > > > like docker image (in the payload) and required artifacts that were > > > staged. > > > >> >>> > > >> > >> 2. It is also the place for additional requirements or > > > hints like "high mem" or "GPU" etc. > > > >> >>> > > >> > >> > > > >> >>> > > >> > >> Every user function has an associated environment, and > > > environments exist only for the purpose of executing user functions. In > > > fact, Environment originated as inline requirements/attributes for a user > > > function proto message and was separated just to make the proto smaller. > > > >> >>> > > >> > >> > > > >> >>> > > >> > >> A PTransform is an abstract concept for organizing the > > > graph, not an executable thing. So a hint/capability/requirement on a > > > PTransform only really makes sense as a scoping mechanism for applying a > > > hint to a bunch of functions within a subgraph. This seems like a user > > > interface concern and the SDK should own propagating the hints. If the > > > hint > > > truly applies to the whole PTransform and *not* the parts, then I am > > > interested in learning about that. > > > >> >>> > > >> > >> > > > >> >>> > > >> > >> Kenn > > > >> >>> > > >> > >> > > > >> >>> > > >> > >> On Mon, Nov 16, 2020 at 10:54 AM Robert Burke < > > > rob...@frantil.com> wrote: > > > >> >>> > > >> > >>> > > > >> >>> > > >> > >>> That's a good question. > > > >> >>> > > >> > >>> > > > >> >>> > > >> > >>> I think the main difference is a matter of scope. > > > Annotations would apply to a PTransform while an environment applies to > > > sets of transforms. A difference is the optional nature of the annotations > > > they don't affect correctness. Runners don't need to do anything with them > > > and still execute the pipeline correctly. > > > >> >>> > > >> > >>> > > > >> >>> > > >> > >>> Consider a privacy analysis on a pipeline graph. An > > > annotation indicating that a transform provides a certain level of > > > anonymization can be used in an analysis to determine if the downstream > > > transforms are encountering raw data or not. > > > >> >>> > > >> > >>> > > > >> >>> > > >> > >>> From my understanding (which can be wrong) > > > environments are rigid. Transforms in different environments can't be > > > fused. "This is the python env", "this is the java env" can't be merged > > > together. It's not clear to me that we have defined when environments are > > > safely fuseable outside of equality. There's value in that simplicity. > > > >> >>> > > >> > >>> > > > >> >>> > > >> > >>> AFIACT environment has less to do with the machines a > > > pipeline is executing on than it does about the kinds of SDK pipelines it > > > understands and can execute. > > > >> >>> > > >> > >>> > > > >> >>> > > >> > >>> > > > >> >>> > > >> > >>> > > > >> >>> > > >> > >>> On Mon, Nov 16, 2020, 10:36 AM Chad Dombrova < > > > chad...@gmail.com> wrote: > > > >> >>> > > >> > >>>>> > > > >> >>> > > >> > >>>>> > > > >> >>> > > >> > >>>>> Another example of an optional annotation is marking > > > a transform to run on secure hardware, or to give hints to > > > profiling/dynamic analysis tools. > > > >> >>> > > >> > >>>> > > > >> >>> > > >> > >>>> > > > >> >>> > > >> > >>>> There seems to be a lot of overlap between this idea > > > and Environments. Can you talk about how you feel they may be different > > > or > > > related? For example, I could see annotations as a way of tagging > > > transforms with an Environment, or I could see Environments becoming a > > > specialized form of annotation. > > > >> >>> > > >> > >>>> > > > >> >>> > > >> > >>>> -chad > > > >> >>> > > >> > >>>> > > > >> >>> > > > > > > > >
