From d9eca5e951fef2fd8101aa043c1c245152ce1418 Mon Sep 17 00:00:00 2001
From: jswhit2 <jwhitaker@Jeffreys-MacBook-Air.local>
Date: Thu, 19 Feb 2026 08:41:10 -0700
Subject: [PATCH] disable parallel support via env var

---
 Changelog       |  1 +
 _build/utils.py |  4 ++++
 setup.py        | 12 +++++++++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/Changelog b/Changelog
index a1de04ffa..7ed7b2626 100644
--- a/Changelog
+++ b/Changelog
@@ -3,6 +3,7 @@
  * Change default encoding for stringtochar/chartostring functions from 'utf-8' to 'utf-8'/'ascii' for dtype.kind='U'/'S'
    (issue #1464).
  * Fix DeprecationWarning for assigning to numpy.ndarray.shape for numpy >= 2.5.0 (issue #1468).
+ * Disable parallel support even if libs support it via DISABLE_PARALLEL_SUPPORT env var (issue #1389).
 
  version 1.7.4 (tag v1.7.4rel)
  ================================
diff --git a/_build/utils.py b/_build/utils.py
index ce7938144..05f8e1995 100644
--- a/_build/utils.py
+++ b/_build/utils.py
@@ -113,6 +113,10 @@ def get_netcdf4_include_dir():
 
 
 def netcdf4_has_parallel_support() -> bool:
+    # disable parallel support even if libs support it (issue #1389)
+    DISABLE_PARALLEL_SUPPORT = bool(int(os.environ.get('DISABLE_PARALLEL_SUPPORT', 0)))
+    if DISABLE_PARALLEL_SUPPORT:
+        return False
     netcdf4_incdir = get_netcdf4_include_dir()
     if os.path.exists(ncmetapath := os.path.join(netcdf4_incdir, "netcdf_meta.h")):
         with open(ncmetapath) as f:
diff --git a/setup.py b/setup.py
index 8c10999ea..8b78ff1d1 100644
--- a/setup.py
+++ b/setup.py
@@ -157,6 +157,8 @@ def extract_version(CYTHON_FNAME):
 USE_NCCONFIG = bool(int(os.environ.get('USE_NCCONFIG', 0)))
 # override use of setup.cfg with env var.
 USE_SETUPCFG = bool(int(os.environ.get('USE_SETUPCFG', 1)))
+# disable parallel support even if libs support it (issue #1389)
+DISABLE_PARALLEL_SUPPORT = bool(int(os.environ.get('DISABLE_PARALLEL_SUPPORT', 0)))
 
 setup_cfg = 'setup.cfg'
 # contents of setup.cfg will override env vars, unless
@@ -412,9 +414,13 @@ def _populate_hdf5_info(dirstosearch, inc_dirs, libs, lib_dirs):
        (netcdf_lib_version > "4.4" and netcdf_lib_version < "4.5"):
         has_cdf5_format = True
 
-    has_parallel_support = check_has_parallel_support(inc_dirs)
-    has_has_not = "has" if has_parallel_support else "does not have"
-    print(f"netcdf lib {has_has_not} parallel functions")
+    if DISABLE_PARALLEL_SUPPORT:
+        has_parallel_support = False
+        print("parallel support disabled via DISABLE_PARALLEL_SUPPORT env var")
+    else:
+        has_parallel_support = check_has_parallel_support(inc_dirs)
+        has_has_not = "has" if has_parallel_support else "does not have"
+        print(f"netcdf lib {has_has_not} parallel functions")
 
     if has_parallel_support:
         # note(stubbiali): mpi4py is not available when using the in-tree build backend