From 5e5ef99ce6cae2179a2cc89b551b187fb97f35fe Mon Sep 17 00:00:00 2001
From: David Bold <davidsch@fedoraproject.org>
Date: Tue, 25 Nov 2025 19:58:05 -0500
Subject: [PATCH 2/2] Ensure netcdf4 is locked while closing

Signed-off-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>
---
 xarray/backends/file_manager.py | 20 +++++++++++++++-----
 xarray/backends/locks.py        |  3 +++
 xarray/backends/netCDF4_.py     |  8 +++-----
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/xarray/backends/file_manager.py b/xarray/backends/file_manager.py
index f7cd4675..cf85eaf3 100644
--- a/xarray/backends/file_manager.py
+++ b/xarray/backends/file_manager.py
@@ -8,7 +8,7 @@ from collections.abc import Callable, Hashable, Iterator, Mapping, MutableMappin
 from contextlib import AbstractContextManager, contextmanager
 from typing import Any, Generic, Literal, TypeVar, cast
 
-from xarray.backends.locks import acquire
+from xarray.backends.locks import NETCDF4_PYTHON_LOCK, acquire
 from xarray.backends.lru_cache import LRUCache
 from xarray.core import utils
 from xarray.core.options import OPTIONS
@@ -89,7 +89,7 @@ class CachingFileManager(FileManager[T_File]):
         *args: Any,
         mode: Any = _OMIT_MODE,
         kwargs: Mapping[str, Any] | None = None,
-        lock: Lock | None | Literal[False] = None,
+        lock: Lock | Literal[False] | None = None,
         cache: MutableMapping[Any, T_File] | None = None,
         manager_id: Hashable | None = None,
         ref_counts: dict[Any, int] | None = None,
@@ -448,9 +448,16 @@ def _remove_del_methods():
 class DummyFileManager(FileManager[T_File]):
     """FileManager that simply wraps an open file in the FileManager interface."""
 
-    def __init__(self, value: T_File, *, close: Callable[[], None] | None = None):
+    def __init__(
+        self,
+        value: T_File,
+        *,
+        close: Callable[[], None] | None = None,
+        lock: Lock | Literal[False] | None = None,
+    ):
         if close is None:
             close = value.close
+        self._lock = lock
         self._value = value
         self._close = close
 
@@ -464,5 +471,8 @@ class DummyFileManager(FileManager[T_File]):
         yield self._value
 
     def close(self, needs_lock: bool = True) -> None:
-        del needs_lock  # unused
-        self._close()
+        if needs_lock and self._lock:
+            with self._lock:
+                self._close()
+        else:
+            self._close()
diff --git a/xarray/backends/locks.py b/xarray/backends/locks.py
index 78444354..e2db5e93 100644
--- a/xarray/backends/locks.py
+++ b/xarray/backends/locks.py
@@ -281,3 +281,6 @@ def ensure_lock(lock: Lock | None | Literal[False]) -> Lock:
     if lock is None or lock is False:
         return DummyLock()
     return lock
+
+
+NETCDF4_PYTHON_LOCK = combine_locks([NETCDFC_LOCK, HDF5_LOCK])
diff --git a/xarray/backends/netCDF4_.py b/xarray/backends/netCDF4_.py
index bb511f9b..5d5d4e74 100644
--- a/xarray/backends/netCDF4_.py
+++ b/xarray/backends/netCDF4_.py
@@ -30,7 +30,7 @@ from xarray.backends.file_manager import (
     PickleableFileManager,
 )
 from xarray.backends.locks import (
-    HDF5_LOCK,
+    NETCDF4_PYTHON_LOCK,
     NETCDFC_LOCK,
     combine_locks,
     ensure_lock,
@@ -67,8 +67,6 @@ if TYPE_CHECKING:
 # string used by netCDF4.
 _endian_lookup = {"=": "native", ">": "big", "<": "little", "|": "native"}
 
-NETCDF4_PYTHON_LOCK = combine_locks([NETCDFC_LOCK, HDF5_LOCK])
-
 
 class BaseNetCDF4Array(BackendArray):
     __slots__ = ("datastore", "dtype", "shape", "variable_name")
@@ -421,7 +419,7 @@ class NetCDF4DataStore(WritableCFDataStore):
                         "argument is provided"
                     )
                 root = manager
-            manager = DummyFileManager(root)
+            manager = DummyFileManager(root, lock=NETCDF4_PYTHON_LOCK)
 
         self._manager = manager
         self._group = group
@@ -520,7 +518,7 @@ class NetCDF4DataStore(WritableCFDataStore):
             )
         else:
             manager = CachingFileManager(
-                netCDF4.Dataset, filename, mode=mode, kwargs=kwargs
+                netCDF4.Dataset, filename, lock=lock, mode=mode, kwargs=kwargs
             )
         return cls(manager, group=group, mode=mode, lock=lock, autoclose=autoclose)
 
-- 
2.52.0