Guard cached parquet GPU columns during compression

[fallintoplace]

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Description

Guard the GPU column vectors created during cached-Parquet compression until they are handed off to a ColumnarBatch. safeMap closes partially produced vectors if a later conversion fails, and closeOnExcept protects the handoff into the batch.

Checklists

Documentation

• Updated for new or modified user-facing features or behaviors
• No user-facing change

Testing

• Added or modified tests to cover new code paths
• Covered by existing tests
  (Please provide the names of the existing tests in the PR description.)
• Not required

Performance

• Tests ran and results are added in the PR description
• Issue filed with a link in the PR description
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[greptile-apps]

Greptile Summary

This PR adds exception-safety guards for the GPU ColumnVector instances produced inside compressColumnarBatchWithParquet. Previously, if any column conversion failed mid-loop, already-produced GpuColumnVector objects would be leaked; the same was true if ColumnarBatch construction threw after all columns were built.

• Replaces the plain for-comprehension over column indices with .toArray.safeMap, so that GpuColumnVector objects accumulated before a failing iteration are automatically closed on exception.
• Wraps the new ColumnarBatch(columns, numRows) call in closeOnExcept(columns), ensuring all column vectors are released if the batch constructor ever throws before it can take ownership.

Confidence Score: 5/5

Safe to merge. The two-line mechanical change is internally consistent: safeMap correctly tracks owned GpuColumnVector outputs, and closeOnExcept correctly guards the handoff into ColumnarBatch.

Both new constructs (safeMap and closeOnExcept on the columns array) are used exactly as documented in the project's Arm.scala and RapidsPluginImplicits, and the type algebra works out cleanly at runtime due to Java array covariance. No incorrect behavior, double-close hazard, or new allocation without a guard is introduced by the diff itself.

No files require special attention.

Important Files Changed

Filename	Overview
sql-plugin/src/main/scala/com/nvidia/spark/rapids/parquet/ParquetCachedBatchSerializer.scala	Adds safeMap + closeOnExcept guards around GPU column vector production in compressColumnarBatchWithParquet; import additions are minimal and correct.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant C as compressColumnarBatch
    participant SM as safeMap
    participant CC as ColumnCastUtil
    participant GCV as GpuColumnVector.from
    participant COE as closeOnExcept(columns)
    participant CB as ColumnarBatch
    participant WR as withResource

    C->>SM: (0 until numCols).toArray.safeMap
    loop for each column i
        SM->>CC: ifTrueThenDeepConvertTypeAtoTypeB(...)
        CC-->>SM: v (ColumnVector)
        SM->>GCV: from(v, dataType)
        alt GpuColumnVector.from throws
            SM->>SM: safeClose already-produced vectors
            SM-->>C: rethrows
        else success
            GCV-->>SM: GpuColumnVector
        end
    end
    SM-->>C: columns: Array[SparkColumnVector]
    C->>COE: closeOnExcept(columns)
    COE->>CB: new ColumnarBatch(columns, numRows)
    alt ColumnarBatch ctor throws
        COE->>COE: safeClose all columns
        COE-->>C: rethrows
    else success
        CB-->>COE: newGpuCB
        COE-->>C: newGpuCB
    end
    C->>WR: withResource(newGpuCB)
    WR->>WR: split/write columns
    WR->>CB: close() closes all GpuColumnVectors

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sequenceDiagram
    participant C as compressColumnarBatch
    participant SM as safeMap
    participant CC as ColumnCastUtil
    participant GCV as GpuColumnVector.from
    participant COE as closeOnExcept(columns)
    participant CB as ColumnarBatch
    participant WR as withResource

    C->>SM: (0 until numCols).toArray.safeMap
    loop for each column i
        SM->>CC: ifTrueThenDeepConvertTypeAtoTypeB(...)
        CC-->>SM: v (ColumnVector)
        SM->>GCV: from(v, dataType)
        alt GpuColumnVector.from throws
            SM->>SM: safeClose already-produced vectors
            SM-->>C: rethrows
        else success
            GCV-->>SM: GpuColumnVector
        end
    end
    SM-->>C: columns: Array[SparkColumnVector]
    C->>COE: closeOnExcept(columns)
    COE->>CB: new ColumnarBatch(columns, numRows)
    alt ColumnarBatch ctor throws
        COE->>COE: safeClose all columns
        COE-->>C: rethrows
    else success
        CB-->>COE: newGpuCB
        COE-->>C: newGpuCB
    end
    C->>WR: withResource(newGpuCB)
    WR->>WR: split/write columns
    WR->>CB: close() closes all GpuColumnVectors

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_{Reviews (1): Last reviewed commit: "Guard cached parquet GPU columns during ..." | Re-trigger Greptile}

[greptile-apps]

Intermediate v resource still unguarded on exception path

ifTrueThenDeepConvertTypeAtoTypeB always returns an owned ColumnVector — either copyToColumnVector() (new allocation) or incRefCount() (bumped ref). If GpuColumnVector.from(v, schema(i).dataType) throws (e.g., the assert typeConversionAllowed(...) fires when running with -ea), v is leaked because nothing closes it on the failure path. Wrapping the from call with closeOnExcept(v) { v => GpuColumnVector.from(v, schema(i).dataType) } would close v only on exception while correctly leaving ownership with the new GpuColumnVector on success.

[nvauto]

NOTE: release/26.08 has been created from main. Please retarget your PR to release/26.08 if it should be included in the release.