checkPhaseThreadLimitHook: rename from openmpCheckPhaseHook, set more thread env vars

(cherry picked from commit 8a597f5ae6)

doc/hooks/check-phase-thread-limit-hook.section.md

@@ -0,0 +1,24 @@
+# checkPhaseThreadLimitHook {#setup-hook-check-phase-thread-limit}
+
+This hook defaults a variety of environment variables known
+to control thread counts to 1. Many of these otherwise default
+to `$(nproc)`, which causes massive overloads on build machines
+if nix build jobs and build cores are already tuned to fully utilize
+compute capacity of a builder without additional parallelism.
+
+Currently sets the following environment variables:
+- [`OMP_NUM_THREADS`](https://www.openmp.org/spec-html/5.0/openmpse50.html)
+- [`OPENBLAS_NUM_THREADS`](https://github.com/OpenMathLib/OpenBLAS/blob/e7b45174355edec1f04de1cabcf5ca6a98ea7fbc/USAGE.md#how-can-i-use-openblas-in-multi-threaded-applications)
+- [`MKL_NUM_THREADS`](https://www.intel.com/content/www/us/en/docs/onemkl/developer-guide-linux/2023-0/mkl-domain-num-threads.html)
+- [`BLIS_NUM_THREADS`](https://github.com/flame/blis/blob/b8b75b4e19459f5d618b57aa814ca38b1d82eb82/docs/Multithreading.md#specifying-multithreading)
+- `VECLIB_MAXIMUM_THREADS`: Only affects darwin, see [`man 7 Accelerate`](https://manp.gs/mac/7/Accelerate)
+- [`NUMBA_NUM_THREADS`](https://numba.readthedocs.io/en/stable/reference/envvars.html#threading-control)
+- [`NUMEXPR_NUM_THREADS`](https://numexpr.readthedocs.io/en/latest/user_guide.html#threadpool-configuration)
+
+The `NIX_CHECK_PHASE_DEFAULT_NUM_THREADS` environment variable
+can be used to override the default thread count limit.
+`dontLimitCheckPhaseThreads = true;` can be used to disable
+thread limiting on an individual package.
+
+This hook will not attempt to override already existing
+definitions for thread count environment variables.

doc/hooks/index.md

@@ -13,6 +13,7 @@ aws-c-common.section.md
 bmake.section.md
 breakpoint.section.md
 cernlib.section.md
+check-phase-thread-limit-hook.section.md
 cmake.section.md
 desktop-file-utils.section.md
 gdk-pixbuf.section.md
@@ -34,7 +35,6 @@ nodejs-install-manuals.section.md
 npm-build-hook.section.md
 npm-config-hook.section.md
 npm-install-hook.section.md
-openmp-check-hook.section.md
 patch-rc-path-hooks.section.md
 perl.section.md
 pkg-config.section.md

doc/hooks/openmp-check-hook.section.md

@@ -1,10 +0,0 @@
-# openmpCheckPhaseHook {#setup-hook-omp-check}
-
-
-This hook can be used to setup a check phase that
-requires running a OpenMP application. It mostly
-serves to limit `OMP_NUM_THREADS` to avoid overloading
-build machines.
-
-This hook will not attempt to override an already existing
-definition of `OMP_NUM_THREADS` in the environment.

doc/redirects.json

@@ -2809,7 +2809,8 @@
   "setup-hook-mpi-check": [
     "index.html#setup-hook-mpi-check"
   ],
-  "setup-hook-omp-check": [
+  "setup-hook-check-phase-thread-limit": [
+    "index.html#setup-hook-check-phase-thread-limit",
     "index.html#setup-hook-omp-check"
   ],
   "ninja": [

pkgs/by-name/ch/checkPhaseThreadLimitHook/hook.sh

@@ -0,0 +1,32 @@
+setupThreadLimit() {
+  # Limit number of threads used during checks. 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.
+
+  # global value to override all of these at once
+  NIX_CHECK_PHASE_DEFAULT_NUM_THREADS="${NIX_CHECK_PHASE_DEFAULT_NUM_THREADS:-1}"
+
+  thread_vars=(
+    OMP_NUM_THREADS
+    OPENBLAS_NUM_THREADS
+    MKL_NUM_THREADS
+    BLIS_NUM_THREADS
+    VECLIB_MAXIMUM_THREADS
+    NUMBA_NUM_THREADS
+    NUMEXPR_NUM_THREADS
+  )
+
+  echo "setting known thread variables to default: $NIX_CHECK_PHASE_DEFAULT_NUM_THREADS"
+  for var in "${thread_vars[@]}"; do
+    export "$var=${!var:-$NIX_CHECK_PHASE_DEFAULT_NUM_THREADS}"
+    printf " %s=%s" "$var" "${!var}"
+  done
+  printf "\n"
+}
+
+
+if [[ -z "${dontLimitCheckPhaseThreads-}" ]]; then
+    echo "Using checkPhaseThreadLimitHook"
+    preCheckHooks+=('setupThreadLimit')
+    preInstallCheckHooks+=('setupThreadLimit')
+fi

pkgs/by-name/ch/checkPhaseThreadLimitHook/package.nix

@@ -0,0 +1,15 @@
+{
+  lib,
+  makeSetupHook,
+}:
+
+makeSetupHook {
+  name = "check-phase-thread-limit-hook";
+
+  __structuredAttrs = true;
+
+  meta = {
+    license = lib.licenses.mit;
+    maintainers = with lib.maintainers; [ grimmauld ];
+  };
+} ./hook.sh

pkgs/by-name/op/openmpCheckPhaseHook/omp-check-hook.sh

@@ -1,11 +0,0 @@
-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}"
-}
-

pkgs/by-name/op/openmpCheckPhaseHook/package.nix

@@ -1,12 +0,0 @@
-{
-  lib,
-  makeSetupHook,
-}:
-
-makeSetupHook {
-  name = "omp-checkPhase-hook";
-
-  __structuredAttrs = true;
-
-  meta.license = lib.licenses.mit;
-} ./omp-check-hook.sh

pkgs/top-level/aliases.nix

@@ -1629,6 +1629,7 @@ mapAliases {
   openjfx23 = throw "OpenJFX 23 was removed as it has reached its end of life"; # Added 2025-11-04
   openjfx24 = throw "OpenJFX 24 was removed as it has reached its end of life"; # Added 2025-10-04
   openmodelica = throw "'openmodelica' has been removed as it was unmaintained in nixpkgs and depends on insecure&unmtaintained qtwebkit"; # Added 2026-04-26
+  openmpCheckPhaseHook = warnAlias "'openmpCheckPhaseHook' has been renamed to 'checkPhaseThreadLimitHook' to reflect its handling of all known thread-limiting mechanisms during check phase" checkPhaseThreadLimitHook; # Added 2026-07-09
   openmw-tes3mp = throw "'openmw-tes3mp' has been removed due to lack of maintenance upstream"; # Added 2025-08-30
   openssl_3_0 = throw "'openssl_3_0' has been renamed to/replaced by 'openssl_3'"; # Converted to throw 2025-10-27
   opensycl = throw "'opensycl' has been renamed to/replaced by 'adaptivecpp'"; # Converted to throw 2025-10-27