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https://issues.apache.org/jira/browse/BEAM-2699?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kenneth Knowles updated BEAM-2699:
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This Jira ticket has a pull request attached to it, but is still open. Did the
pull request resolve the issue? If so, could you please mark it resolved? This
will help the project have a clear view of its open issues.
> AppliedPTransform is used as a key in hashmaps but PTransform is not
> hashable/equality-comparable
> -------------------------------------------------------------------------------------------------
>
> Key: BEAM-2699
> URL: https://issues.apache.org/jira/browse/BEAM-2699
> Project: Beam
> Issue Type: Bug
> Components: runner-core
> Reporter: Eugene Kirpichov
> Priority: P3
>
> There's plenty of occurrences in runners-core of Map or BiMap where the key
> is an AppliedPTransform.
> However, PTransform does not advertise that it is required to implement
> equals/hashCode, and some transforms can't do it properly anyway - for
> example, transforms that capture a ValueProvider which is also not
> hashable/eq-comparable. I'm surprised that things aren't already very broken
> because of this.
> Fundamentally, I don't see why we should ever compare two PTransform's for
> equality.
> I looked at the code and wondered "can AppliedPTransform simply be
> identity-hashable", but right now the answer is no because we can create an
> AppliedPTransform for the same transform applied to the same thing multiple
> times.
> Fixing that appears to be not very easy, but definitely possible. Ideally
> TransformHierarchy.Node would just know its AppliedPTransform, however a Node
> can be constructed when there's yet no Pipeline. Suppose there's gotta be
> some way to propagate a Pipeline into Node.finishSpecifying() (which should
> be called exactly once on the Node, and this should be enforced), and have
> finishSpecifying() return the AppliedPTransform, and have the caller use that
> instead of potentially repeatedly calling .toAppliedPTransform() on the same
> Node.
> [~kenn] is on vacation but perhaps [~tgroh] can help with this meanwhile?
> CC: [~reuvenlax]
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