emscripten-core/emscripten

PATH.normalize is incredibly expensive.

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#16,858 创建于 2022年5月2日

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good first bughelp wanted

描述

I profiled a WebGL Unity game that had analytics enabled, and by far the most expensive call chain was PATH.normalize and related, in particular because of the .join("/") call. Just replacing the body of normalize with if(path[0] === "/" && path[1] === "/") return path.slice(1); return path; fixed the constant stutters that I was looking at. I cannot stress enough how much of a performance increase this was. Checking if the string is already normalized should help immensely.

I'm sorry I don't have any hard statistics ready for you, but just profiling any Unity game that has frequent virtual FS access (as with Unity's analytics enabled) with the Firefox Profiler should show it immediately.

I'm unsure what version of Emscripten was used in the game I profiled, but PATH.normalize is completely unchanged relative to now.

贡献者指南

技术栈
ccppjavascriptwasm
领域
backendperformance
议题类型
performance
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。
2
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。
under 1 hour
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。
stale
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
JavaScriptEmscripten development workflow
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。
70
研究方向
Locate the PATH.normalize function in the Emscripten source code, likely in src/shell.js. Review the current implementation and confirm that the proposed fix (replacing the body with a check for double leading slashes) does not break other use cases. Consider edge cases such as trailing slashes or other redundant path separators. Write a test for the function and submit a pull request with the change.
PATH.normalize is incredibly expensive. · emscripten-core/emscripten#16858 | Good First Issue