zhengruifeng opened a new pull request, #58101:
URL: https://github.com/apache/spark/pull/58101
### What changes were proposed in this pull request?
This PR optimizes `IsotonicRegressionModel.transform` by snapshotting the
underlying
`boundaries` and `predictions` arrays before creating the transform UDF. The
double and vector
feature transform paths now call an array-backed companion helper instead of
closing over the
legacy `mllib.regression.IsotonicRegressionModel` wrapper.
The legacy `mllib.regression.IsotonicRegressionModel` prediction path also
reuses the helper, and
its RDD prediction path snapshots the arrays before creating the map closure.
### Why are the changes needed?
Avoiding the model capture reduces transform-closure retained memory, which
is useful for Spark
Connect server workloads and follows the closure-size optimizations tracked
under SPARK-58584.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Ran local static checks:
```
git diff --check HEAD~1 HEAD
grep -rn -P "[^\x00-\x7F]"
mllib/src/main/scala/org/apache/spark/ml/regression/IsotonicRegression.scala
mllib/src/main/scala/org/apache/spark/mllib/regression/IsotonicRegression.scala
awk 'length>100 && $0 !~ /^[[:space:]]*(import|package) / && $0 !~
/https?:\/\// {print FILENAME":"FNR": "length" chars"}'
mllib/src/main/scala/org/apache/spark/ml/regression/IsotonicRegression.scala
mllib/src/main/scala/org/apache/spark/mllib/regression/IsotonicRegression.scala
```
Compiled MLlib:
```
build/sbt -java-home /usr/lib/jvm/java-17-openjdk-amd64 mllib/compile
```
Measured serialized `ScalaUDF.function` closure size with a temporary local
probe:
| Case | Before | After | Delta |
|---|---:|---:|---:|
| `isotonic.double` | 3862 B | 1354 B | -2508 B, -64.9% |
| `isotonic.vector` | 3931 B | 1547 B | -2384 B, -60.6% |
No unit test was added because this is an internal refactor of existing
prediction logic.
### Was this patch authored or co-authored using generative AI tooling?
Generated-by: Codex (GPT-5)
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
