From b6e39b216d88ce807410f1e05908d9cdbb4afb39 Mon Sep 17 00:00:00 2001
From: Martin Weinelt <hexa@darmstadt.ccc.de>
Date: Thu, 25 Jun 2026 00:44:12 +0200
Subject: [PATCH] python3Packages.x-transformers: limit openmp threads during
 tests

---
 pkgs/development/python-modules/x-transformers/default.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkgs/development/python-modules/x-transformers/default.nix b/pkgs/development/python-modules/x-transformers/default.nix
index 16d3dff4fd61..1496775f5eec 100644
--- a/pkgs/development/python-modules/x-transformers/default.nix
+++ b/pkgs/development/python-modules/x-transformers/default.nix
@@ -42,6 +42,10 @@ buildPythonPackage (finalAttrs: {
 
   nativeCheckInputs = [ pytestCheckHook ];
 
+  preCheck = ''
+    export OMP_NUM_THREADS=1
+  '';
+
   # RuntimeError: torch.compile is not supported on Python 3.14+
   disabledTests = lib.optionals (pythonAtLeast "3.14") [ "test_up" ];