rapidsai/cudf

Audit pylibcudf for `noexcept`/`nogil` and remove "Exception check … requires the GIL" warnings

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#19,720 创建于 2025年8月18日

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Pythonbuggood first issue

描述

Describe the bug When building pylibcudf, our CI logs show many performance warnings like:

performance hint: /__w/cudf/cudf/python/pylibcudf/pylibcudf/labeling.pyx:56:22:
Exception check after calling 'view' will always require the GIL to be acquired.
Declare 'view' as 'noexcept' if you control the definition and you're sure you
don't want the function to raise exceptions.

Example

https://github.com/rapidsai/cudf/actions/runs/17040978623/job/48305629162?pr=19446#step:12:330

Steps/Code to reproduce bug build pylibcudf with warnings

We should check pylibcudf for places where we’ve declared except * or except + but the C++ is non-throwing.

Expected behavior No perf warnings

Additional context Was recently fixed in RMM. See https://github.com/rapidsai/rmm/pull/2020

贡献者指南

技术栈
cpppython
领域
dataperformance
议题类型
bug
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
4
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
1-2 days
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
fresh
清晰度议题是否清楚说明期望改动、验收标准和下一步。
clear
前置要求
C++ exception handlingCython syntaxBuilding pylibcudf with warnings
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
45
研究方向
Start by building pylibcudf with warnings enabled to reproduce the issue (see CI logs linked). Examine the Cython .pyx files in pylibcudf for functions that have 'except *' or 'except +' declarations but call C++ functions that are marked noexcept. Compare with the approach in the RMM PR (rapidsai/rmm/pull/2020) which added noexcept to non throwing C++ functions. The goal is to add noexcept to all such C++ functions in cuDF called from Cython, and remove unnecessary except clauses in .pyx files.