GBM: scoring for validation_frame should be incremental as GBM adds trees

Description

GBM has non-linear slowdown with ntrees, presumably due to scoring of the validation_frame. This showed up with AutoML on Driverless-munged Homesite. I've marked this as a Blocker because it prevents us from using h2o-3 AutoML with Driverless.

The training data can be found at mr-0xc9:~rpeck/homesite.

A script to repro is here:

Assignee

Michal Kurka

Fix versions

None

Reporter

Raymond Peck

Support ticket URL

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Affected Spark version

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Customer Request Type

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Task progress

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CustomerVisible

No

Components

Sprint

None

Priority

Blocker
Configure