JuliaLang/julia

`JULIA_NUM_THREADS` ignored when embedding Julia on a Windows system

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#55,468 opened on 2024年8月12日

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bughelp wantedsystem:windows

説明

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).

コントリビューターガイド

技術スタック
なし
領域
backendapi
Issue 種別
bug
難度新しい貢献者にとっての実装難度です。1 は非常に小さな変更、5 は専門的な作業です。
4
推定時間経験ある貢献者が調査、実装、テスト、pull request 準備にかけるおおよその時間範囲です。
half day
活動状況Issue が今どれだけ取り組みやすいかを示します。新しい、活発、古い、ブロック中、またはメンテナー入力待ちなどです。
fresh
明確さ期待される変更、受け入れ条件、次の手順がどれだけ明確かを示します。
clear
前提条件
Knowledge of Julia's C APIFamiliarity with Windows environment variablesC programming experienceExperience with multithreading
初心者向け度初回貢献者にどれだけ取り組みやすいかを 1-100 で推定したスコアです。
25
調査方針
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.