From 8ff970916b975cfd1b79ff3751061526fe88614b Mon Sep 17 00:00:00 2001
From: Grimmauld <Grimmauld@grimmauld.de>
Date: Fri, 26 Jun 2026 17:40:20 +0200
Subject: [PATCH] openmpCheckPhaseHook: init

---
 .../op/openmpCheckPhaseHook/omp-check-hook.sh        | 11 +++++++++++
 pkgs/by-name/op/openmpCheckPhaseHook/package.nix     | 12 ++++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 pkgs/by-name/op/openmpCheckPhaseHook/omp-check-hook.sh
 create mode 100644 pkgs/by-name/op/openmpCheckPhaseHook/package.nix

diff --git a/pkgs/by-name/op/openmpCheckPhaseHook/omp-check-hook.sh b/pkgs/by-name/op/openmpCheckPhaseHook/omp-check-hook.sh
new file mode 100644
index 000000000000..b3279b170360
--- /dev/null
+++ b/pkgs/by-name/op/openmpCheckPhaseHook/omp-check-hook.sh
@@ -0,0 +1,11 @@
+preCheckHooks+=('setupOmpCheck')
+preInstallCheckHooks+=('setupOmpCheck')
+
+
+setupOmpCheck() {
+  # Limit number of OpenMP threads. Default is "all cores".
+  # Using all cores causes high load on builders if checks are executed with NIX_BUILD_CORE parallelism.
+  # This gets even worse if multiple builds are scheduled on the same machine, potentially growing O(n^3) without explicit core limits.
+  export OMP_NUM_THREADS="${OMP_NUM_THREADS:-1}"
+}
+
diff --git a/pkgs/by-name/op/openmpCheckPhaseHook/package.nix b/pkgs/by-name/op/openmpCheckPhaseHook/package.nix
new file mode 100644
index 000000000000..9e30609e8de5
--- /dev/null
+++ b/pkgs/by-name/op/openmpCheckPhaseHook/package.nix
@@ -0,0 +1,12 @@
+{
+  lib,
+  makeSetupHook,
+}:
+
+makeSetupHook {
+  name = "omp-checkPhase-hook";
+
+  __structuredAttrs = true;
+
+  meta.license = lib.licenses.mit;
+} ./omp-check-hook.sh