[FEA] Add Java bindings for multi-output and reusable AST JIT execution by thirtiseven · Pull Request #23828 · NVIDIA/cudf

thirtiseven · 2026-08-26T08:18:48Z

Description

This PR exposes the libcudf AST JIT capabilities introduced by #23615 and #23621 through the Java API, and adds a reusable Java binding for cudf::transform_program introduced by #23648.

The execution backend is selected when an expression is compiled:

AstExpression.compile() preserves the existing behavior and produces an expression compatible with default AST consumers.
AstExpression.compileJit() produces a JIT-specific expression. Each CompiledExpression owns only the native AST tree and literal representation required by its compilation mode.
CompiledExpression.computeColumn(Table) executes using the compiled expression's mode, avoiding a separate computeColumnJit API and avoiding duplicate native AST trees.
CompiledExpression.computeTableJit(Table, CompiledExpression...) evaluates multiple JIT-compiled expressions in one compute_table_jit call. Output order follows the supplied expression order, and libcudf Row IR can eliminate structurally equivalent subexpressions across outputs.

For JIT-compiled expressions, literals are converted to one-row columns once during compilation and retained for repeated evaluation. Temporary scalar owners are released after construction completes. Default-compiled expressions retain the existing scalar-backed representation and do not incur the JIT literal-column allocation cost.

The new AstJitProgram API exposes reusable AST JIT execution:

AstJitProgram.compile(Table, CompiledExpression...) lowers one or more JIT expressions and retrieves a cudf::transform_program specialized to the referenced input-column types and physical nullability.
AstJitProgram.computeTable(Table) reuses the lowered program and retrieved kernel across compatible input tables. Row counts and unreferenced columns may differ between evaluations.
The program does not retain the schema table or source expressions and remains valid after they are closed.

To support this ownership contract, cudf::transform_program now copies scalar_column_view literal inputs into program-owned columns. Device-owning compiled expressions and programs are also registered with the RMM cleanup path.

Reusable programs amortize repeated AST lowering, kernel lookup, and warm dispatch-side overhead. They do not reduce first-use or cold JIT compilation latency.

The binding also:

rejects compilation-mode mismatches, including passing default-compiled expressions to JIT APIs;
prevents JIT-compiled expressions from being passed to default-only consumers such as join and scan predicates;
validates null, closed, and schema-incompatible inputs;
preserves the lifetime of input tables and compiled expressions across JNI calls.

The compileJit and direct multi-output APIs are consumed by NVIDIA/cudf-spark#15312 to execute compatible Project expressions as multi-output AST JIT waves.

Checklist

I am familiar with the Contributing Guidelines.
New or existing tests cover these changes.
The documentation is up to date with these changes.

Expose computeTableJit to evaluate compiled AST roots in one libcudf call. Keep scalar-column-backed JIT trees alongside regular trees so compiled literals can be reused across evaluations. Signed-off-by: Haoyang Li <haoyangl@nvidia.com>

copy-pr-bot · 2026-08-26T08:18:51Z

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Signed-off-by: Haoyang Li <haoyangl@nvidia.com>

coderabbitai · 2026-08-27T05:19:56Z

📝 Walkthrough

Summary by CodeRabbit

New Features
- Added explicit JIT compilation for AST expressions.
- Added multi-expression table evaluation and reusable, schema-specialized JIT programs.
- Added validation for incompatible execution paths, inputs, and schemas.
Bug Fixes
- Improved resource safety and literal ownership during JIT evaluation.
- Preserved input data when validation or computation fails.
Documentation
- Updated guidance for JIT operations and decimal literals.
Tests
- Expanded coverage for outputs, literals, nullability, casting, overflow, reuse, and validation.

Walkthrough

The AST API now supports explicit default and JIT compilation modes. JIT expressions support multi-output table computation and reusable schema-specialized programs. Native literal ownership and resource cleanup are updated. Tests cover validation, lifecycle, literals, nullability, overflow, casts, and decimal behavior.

Changes

JIT AST execution

Layer / File(s)	Summary
Java compilation and evaluation APIs `java/src/main/java/ai/rapids/cudf/ast/{AstExpression,CompiledExpression,JitOperation,Literal}.java`	Adds `compileJit()`, stores compilation mode, adds `computeTableJit`, restricts incompatible native-handle access, and updates JIT documentation.
Native compilation modes `java/src/main/native/src/{jni_compiled_expr.hpp,CompiledExpression.cpp}`	Stores compilation mode, creates JIT literal columns, validates JIT operations, releases staging scalars, and exposes separate compilation entry points.
Multi-output JIT execution `java/src/main/native/src/{CompiledExpression.cpp,AstJitProgram.cpp}`, `java/src/main/native/CMakeLists.txt`	Replaces single-expression JIT computation with multi-output table evaluation and adds native `AstJitProgram` lifecycle support.
Reusable schema-specialized JIT programs `java/src/main/java/ai/rapids/cudf/ast/AstJitProgram.java`, `java/src/main/java/ai/rapids/cudf/MemoryCleaner.java`	Adds schema-specialized program compilation, table computation, explicit closing, leak cleanup, and RMM-blocker registration.
JIT API validation and regression coverage `java/src/test/java/ai/rapids/cudf/ast/{CompiledExpressionTest,AstJitProgramTest}.java`, `cpp/{src/transform/transform.cu,tests/ast/transform_tests.cpp}`	Covers mode validation, handle restrictions, repeated inputs, literals, multi-output results, failures, overflow, casts, decimal behavior, program lifecycle, and scalar-column literal ownership.

Estimated code review effort: 4 (Complex) | ~45 minutes

Merge Risk: 🟠 High · up to 983fc

The PR adds reusable multi-output JIT execution, but the current implementation can produce incorrect results when retained literals are used across streams and can crash the process if execution overlaps with cleanup. These correctness and availability risks should be fixed before merging.

Suggested reviewers: igorpeshansky, mythrocks, nartal1

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 17.05% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 88 functions across 13 files. (1 skipped:…	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the main changes: Java bindings for multi-output and reusable AST JIT execution.
Description check	✅ Passed	The description directly explains the Java AST JIT bindings, multi-output execution, reusable programs, validation, ownership, and testing changes in the pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 17.05% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 88 functions across 13 files. (1 skipped: 1 unsupported.)

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…literal-jni

Copy prepared scalar column views into program-owned columns so reusable AST programs remain valid after their source expressions are destroyed. Signed-off-by: Haoyang Li <haoyangl@nvidia.com>

Expose schema-specialized transform_program construction and reuse from Java. Preserve literal ownership across program reuse, validate compilation modes and schemas, and cover multi-output execution. Signed-off-by: Haoyang Li <haoyangl@nvidia.com>

coderabbitai · 2026-09-01T09:06:46Z

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Actionable comments posted: 1

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Inline comments:
In `@cpp/src/transform/transform.cu`:
- Around line 1524-1527: The retained scalar-column copies created in the
scalar_column_view handling must be synchronized before transform_program::run
consumes ast_scalar_columns_. Either record an event on the construction stream
and make every run stream wait for it, or synchronize the construction stream
before returning; update the regression test to construct and run with different
streams.

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📥 Commits

Reviewing files that changed from the base of the PR and between e3fd258 and 983fc16.

📒 Files selected for processing (14)

cpp/src/transform/transform.cu
cpp/tests/ast/transform_tests.cpp
java/src/main/java/ai/rapids/cudf/MemoryCleaner.java
java/src/main/java/ai/rapids/cudf/ast/AstExpression.java
java/src/main/java/ai/rapids/cudf/ast/AstJitProgram.java
java/src/main/java/ai/rapids/cudf/ast/CompiledExpression.java
java/src/main/java/ai/rapids/cudf/ast/JitOperation.java
java/src/main/java/ai/rapids/cudf/ast/Literal.java
java/src/main/native/CMakeLists.txt
java/src/main/native/src/AstJitProgram.cpp
java/src/main/native/src/CompiledExpression.cpp
java/src/main/native/src/jni_compiled_expr.hpp
java/src/test/java/ai/rapids/cudf/ast/AstJitProgramTest.java
java/src/test/java/ai/rapids/cudf/ast/CompiledExpressionTest.java

🚧 Files skipped from review as they are similar to previous changes (7)

java/src/main/java/ai/rapids/cudf/ast/JitOperation.java
java/src/main/java/ai/rapids/cudf/ast/AstExpression.java
java/src/main/java/ai/rapids/cudf/ast/Literal.java
java/src/main/native/src/CompiledExpression.cpp
java/src/main/native/src/jni_compiled_expr.hpp
java/src/main/java/ai/rapids/cudf/ast/CompiledExpression.java
java/src/test/java/ai/rapids/cudf/ast/CompiledExpressionTest.java

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Add Java bindings for multi-output AST JIT

aa0963c

Expose computeTableJit to evaluate compiled AST roots in one libcudf call. Keep scalar-column-backed JIT trees alongside regular trees so compiled literals can be reused across evaluations. Signed-off-by: Haoyang Li <haoyangl@nvidia.com>

github-actions Bot added the Java Affects Java cuDF API. label Aug 26, 2026

github-actions Bot assigned thirtiseven Aug 26, 2026

thirtiseven added feature request New feature or request Spark Functionality that helps Spark RAPIDS non-breaking Non-breaking change labels Aug 26, 2026

refator to new api

e37a829

Signed-off-by: Haoyang Li <haoyangl@nvidia.com>

thirtiseven mentioned this pull request Aug 26, 2026

Add experimental Project AST JIT for integral add and multiply [fast-ut] [databricks] NVIDIA/cudf-spark#15312

Draft

8 tasks

thirtiseven marked this pull request as ready for review August 27, 2026 05:13

thirtiseven requested a review from a team as a code owner August 27, 2026 05:13

thirtiseven requested a review from nartal1 August 27, 2026 05:13

thirtiseven requested review from igorpeshansky, lamarrr and mythrocks August 27, 2026 05:28

thirtiseven mentioned this pull request Sep 1, 2026

[FEA] Follow-up: Re-evaluate AST JIT multi-output group limits NVIDIA/cudf-spark#15853

Open

thirtiseven added 3 commits September 1, 2026 15:24

Merge remote-tracking branch 'origin/main' into ast-jit-multi-output-…

41a0eb5

…literal-jni

Fix transform program scalar literal ownership

6ac19c8

Copy prepared scalar column views into program-owned columns so reusable AST programs remain valid after their source expressions are destroyed. Signed-off-by: Haoyang Li <haoyangl@nvidia.com>

thirtiseven requested a review from a team as a code owner September 1, 2026 09:06

github-actions Bot added libcudf Affects libcudf (C++/CUDA) code. CMake CMake build issue labels Sep 1, 2026

thirtiseven changed the title ~~[FEA] Add Java bindings for multi-output AST JIT~~ [FEA] Add Java bindings for multi-output and reusable AST JIT execution Sep 1, 2026

coderabbitai Bot reviewed Sep 1, 2026

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Comment thread cpp/src/transform/transform.cu

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[FEA] Add Java bindings for multi-output and reusable AST JIT execution - #23828

[FEA] Add Java bindings for multi-output and reusable AST JIT execution#23828
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