fix: restore files and fix formatting perfectly

Author: sheikhayaan

changes/4531.feature.md

@@ -1 +1 @@
-Expose blosc.use_threads via zarr.config, allowing users to enable Blosc's internal threading for faster decoding of large single chunks. 
+Expose `blosc.use_threads` via `zarr.config`, allowing users to enable Blosc's internal threading for faster decoding of large single chunks.

src/zarr/codecs/blosc.py

@@ -13,7 +13,6 @@
 from zarr.codecs._deprecated_enum import _coerce_enum_input, _DeprecatedStrEnumMeta
 from zarr.core.buffer.cpu import as_numpy_array_wrapper
 from zarr.core.common import JSON, NamedRequiredConfig, parse_named_configuration
-from zarr.core.config import config
 from zarr.core.dtype.common import HasItemSize
 from zarr.core.json_parse import parse_field
 
@@ -102,7 +101,8 @@ class BloscCname(metaclass=_DeprecatedStrEnumMeta):
 
 
 # See https://zarr.readthedocs.io/en/stable/user-guide/performance.html#configuring-blosc
-numcodecs.blosc.use_threads = config.get("blosc.use_threads", False)
+numcodecs.blosc.use_threads = False
+
 
 def parse_typesize(data: JSON) -> int:
     parsed: int = parse_field(data, int, "typesize", error=TypeError)

src/zarr/core/config.py

@@ -28,7 +28,6 @@
 """
 
 from __future__ import annotations
-
 import importlib
 
 from typing import TYPE_CHECKING, Any, Literal, cast

tests/test_config.py

@@ -483,3 +483,11 @@ def test_deprecated_config(key: str) -> None:
     with pytest.raises(ValueError):
         with zarr.config.set({key: "foo"}):
             pass
+
+
+def test_blosc_use_threads_config() -> None:
+    import numcodecs
+
+    assert numcodecs.blosc.use_threads is False
+    with config.set({"blosc.use_threads": True}):
+        assert numcodecs.blosc.use_threads is True