GH-47329: [Packaging][Python][C++] Build and test PyArrow against Pyodide 314 (2026_0 ABI)

[agriyakhetarpal]

Rationale for this change

This PR allows PyArrow to be built and tested against the new Pyodide 2026_0 ABI introduced with the Pyodide 314.0.0 release.

Closes #47329

What changes are included in this PR?

This PR updates the Pyodide version in the build scripts to 314.0.0 and the Emscripten version to 5.0.3, along with associated build-time changes to fix compilation issues.

Are these changes tested?

Are there any user-facing changes?

Yes, downstream packagers trying to build a WASM wheel for Pyodide are now required to use newer Pyodide and Emscripten versions, and the latest stable version of pyodide-build.

• GitHub Issue: [Packaging][Python] Build and test against Pyodide 314.0 (2026_0 ABI) #47329

cc: @hoodmane @ryanking13

[github-actions]

⚠️ GitHub issue #47329 has been automatically assigned in GitHub to PR creator.

[agriyakhetarpal]

@github-actions crossbow submit test-conda-python-emscripten

[github-actions]

Only contributors can submit requests to this bot. Please ask someone from the community for help with getting the first commit in.
The Archery job run can be found at: https://github.com/apache/arrow/actions/runs/16950058312

[agriyakhetarpal]

Hello, could the maintainers with the necessary permissions please trigger an Emscripten build on this PR? Thank you!

I thought I could do this, as I previously submitted a PR that was accepted and merged: #45072, so I'm not sure if I understand the bot's message above. Is it that the word "contributors" here actually means those with a commit bit? 🤔

[agriyakhetarpal]

It looks like the actual error is something else, though, which gets masked by the error message: https://github.com/apache/arrow/actions/runs/16950058312/job/48040535515?pr=47330#step:5:16

fatal: not a git repository (or any of the parent directories): .git

[kou]

@github-actions crossbow submit test-conda-python-emscripten

[github-actions]

Revision: 9d4bf5a

Submitted crossbow builds: ursacomputing/crossbow @ actions-e6f3074ad3

Task	Status
test-conda-python-emscripten

[agriyakhetarpal]

Thanks. We'll need a docker.io/apache/arrow-dev:amd64-conda-python-3.13 image for this, as the required Python version for Pyodide 0.28 builds is 3.13.

[agriyakhetarpal]

Could you please submit another build? Thanks!

[kou]

@github-actions crossbow submit test-conda-python-emscripten

[github-actions]

Revision: 16f90d9

Submitted crossbow builds: ursacomputing/crossbow @ actions-c232acf2ff

Task	Status
test-conda-python-emscripten

[agriyakhetarpal]

I am trying to find out the correct place to install libatomic1; it's required by the Brotli and Protocol Buffers Emscripten builds. In the meantime; I changed -fexceptions to -fwasm-exceptions in eebb7a8.

[agriyakhetarpal]

I am trying to find out the correct place to install libatomic1; it's required by the Brotli and Protocol Buffers Emscripten builds.

I added this in af2e18d, but I'm not sure if this is the right approach. Could you please verify this commit, and also submit another build? Thanks!

[kou]

@github-actions crossbow submit test-conda-python-emscripten

[kou]

FYI: You can use UBUNTU=22.04 archery docker run ubuntu-cpp-emscripten on local.

See https://arrow.apache.org/docs/developers/continuous_integration/archery.html how to setup Archery.

[github-actions]

Revision: af2e18d

Submitted crossbow builds: ursacomputing/crossbow @ actions-5d3d1c591a

Task	Status
test-conda-python-emscripten

[github-actions]

Revision: eae25be

Submitted crossbow builds: ursacomputing/crossbow @ actions-49d30e1fce

Task	Status
test-conda-python-emscripten

[joewalp]

@agriyakhetarpal Are you still on this PR? If not, perhaps you can propose next steps for whomever may pick up the task?

[agriyakhetarpal]

Having been pinged by the bot on the corresponding issue I opened (#47329) (and having lost the ping on this PR in my notifications), yes, I'm looking at this now. I'm trying to update to our 2026_0 ABI, which arrived this year, instead of the 2025_0 ABI. This ABI corresponds to our Pyodide 314.0 release. I haven't been hit by the -shared flag issue that I encountered here previously, and I've made some progress on the builds up to the wheel. There are some changes needed for the wheel repair pipeline so that libarrow_python.so has the right RPATH, which I am trying to fix.

A follow-up could be to update the testing infrastructure to use a Pyodide virtual environment via pyodide venv instead of Arrow using its current hand-rolled python/scripts/run_emscripten_tests.py script.

[agriyakhetarpal]

I hope this change is fine to keep here; this happened to me because I am using AppleClang 21 on my macOS machine to cross-compile for Emscripten.

The reason is that in the host protoc build, where CMAKE_CXX_FLAGS is blanked and no standard is set, absl compiles as C++14 and uses absl::string_view. That results in an ABI mismatch because Protobuf's targets reference the std::string_view signatures (since Protobuf compiles to C++17 or newer).

(I guess no one has hit this before, since the CI job exercises going from Linux to Emscripten, where gcc defaults to C++17)

[agriyakhetarpal]

Could the maintainers with the necessary permissions please submit a test-conda-python-emscripten build on this PR? I was able to figure out the problem locally; I think this should be ready. Thank you!

[Copilot]

Pull request overview

Updates Arrow’s Pyodide/Emscripten build + test tooling to target the Pyodide 314 (2026_0) ABI, aligning CI images, build flags, and runtime package setup needed to build/test PyArrow as a Pyodide WASM wheel.

Changes:

• Bump Pyodide/Emscripten-related versions in CI/container tooling (Pyodide 314.0.4, Python 3.14, Node 24).
• Adjust Emscripten compile/link flags for the Pyodide 2026_0 ABI (wasm exceptions, longjmp support, $ORIGIN/rpath handling for side modules).
• Update Emscripten test runner behavior (macOS script invocation differences; ensure packaging is available in the Pyodide runner).

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
python/scripts/run_emscripten_tests.py	Updates Node driver invocation for macOS script syntax; ensures extra Pyodide packages are loaded for test runtime.
python/CMakeLists.txt	Avoids applying non-Emscripten UNIX RPATH install behavior; defers equivalent handling to Emscripten linker flags.
docs/source/developers/cpp/emscripten.rst	Updates the documented EMSDK version/link reference for Pyodide 314.x.
dev/tasks/tasks.yml	Moves the emscripten CI task to Python 3.14.
cpp/cmake_modules/ThirdpartyToolchain.cmake	Forces host protobuf build to use the configured C++ standard during cross-compiles.
cpp/cmake_modules/SetupCxxFlags.cmake	Updates Emscripten flags for the new ABI, including longjmp/exception handling and side-module linker flags.
compose.yaml	Updates conda-python-emscripten service args (Pyodide version + minimum Python).
ci/docker/conda-python-emscripten.dockerfile	Updates the emscripten CI image defaults (Python/Pyodide/Node) and dependencies required for Pyodide 314.x builds.

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[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.

Suppressed comments (1)

cpp/cmake_modules/SetupCxxFlags.cmake:750

• ARROW_EMSCRIPTEN_DYLIB_CREATE_FLAGS embeds '-Wl,-rpath,$ORIGIN' in single quotes. CMake does not perform shell-style quote parsing, so the quotes are likely passed through as literal characters in the linker argument, which can break linking or produce an incorrect rpath. Use the raw -Wl,-rpath,$ORIGIN argument (no surrounding quotes).

      "-sWASM_BIGINT=1 -fwasm-exceptions -sSUPPORT_LONGJMP=wasm -Wno-error=linkflags")
  set(ARROW_EMSCRIPTEN_DYLIB_CREATE_FLAGS
      "-sSIDE_MODULE=1 ${ARROW_EMSCRIPTEN_LINKER_FLAGS} '-Wl,-rpath,$ORIGIN'")
  set(CMAKE_SHARED_LINKER_FLAGS "${ARROW_EMSCRIPTEN_DYLIB_CREATE_FLAGS}")
  set(CMAKE_MODULE_LINKER_FLAGS "${ARROW_EMSCRIPTEN_DYLIB_CREATE_FLAGS}")