JuliaLang/julia

`JULIA_NUM_THREADS` ignored when embedding Julia on a Windows system

Open

#55,468 建立於 2024年8月12日

在 GitHub 查看
 (1 留言) (0 反應) (0 負責人)Julia (48,709 star) (5,773 fork)batch import
bughelp wantedsystem:windows

描述

The following c# code...

Environment.SetEnvironmentVariable("JULIA_NUM_THREADS", "4");
jl_init_with_image__threading(mBinPath, mSysImg);
jl_eval_string("println(\"Threads=$(Threads.nthreads())\")");
jl_eval_string("println(\"JULIA_NUM_THREADS=$(ENV[\"JULIA_NUM_THREADS\"])\")");

Produces the following output

Threads=1
JULIA_NUM_THREADS=4

In discussions with the Jeff and Keno it appears this happens in Windows because there are several environment stores in Windows, and the threads are created by reading with getenv (which access the machine level environment), while later in Julia the ENV is retrieved using getenvw (which access the process level environment).

貢獻者指南

技術棧
無
領域
backendapi
議題類型
bug
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
4
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
half day
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
fresh
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
clear
前置要求
Knowledge of Julia's C APIFamiliarity with Windows environment variablesC programming experienceExperience with multithreading
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
25
研究方向
Investigate the Windows environment variable handling in Julia's embedding initialization. The issue mentions that `getenv` reads machine level environment while `getenvw` reads process level. Look at the Julia source code, particularly the thread creation path and the `jl init with image threading` function, to see where `JULIA NUM THREADS` is read. The fix likely involves using the Windows `GetEnvironmentVariable` or ` wgetenv` consistently. Refer to the discussion with Jeff and Keno for further details.