From 1d5fe677aaf34eee3e2d310416ac0b2826d80c30 Mon Sep 17 00:00:00 2001
From: Martin Weinelt <hexa@darmstadt.ccc.de>
Date: Wed, 24 Jun 2026 16:06:45 +0200
Subject: [PATCH] python3Packages.scikit-bio: reduce openmp threads during
 tests

The tests finish quickly enough with just a single OpenMP thread and this
prevents it from becoming a scheduling nightmare on hydra.
---
 pkgs/development/python-modules/scikit-bio/default.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkgs/development/python-modules/scikit-bio/default.nix b/pkgs/development/python-modules/scikit-bio/default.nix
index 1190d875005a..c909d8d66d08 100644
--- a/pkgs/development/python-modules/scikit-bio/default.nix
+++ b/pkgs/development/python-modules/scikit-bio/default.nix
@@ -62,6 +62,10 @@ buildPythonPackage (finalAttrs: {
     pytestCheckHook
   ];
 
+  preCheck = ''
+    export OMP_NUM_THREADS=1
+  '';
+
   # only the $out dir contains the built cython extensions, so we run the tests inside there
   enabledTestPaths = [ "${placeholder "out"}/${python.sitePackages}/skbio" ];