merge

Author: normanrz

.github/workflows/ci.yaml

@@ -12,9 +12,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13.0"]
+        python-version: ["3.11", "3.12", "3.13"]
         # macos-12 is an intel runner, macos-14 is a arm64 runner
-        platform: [ubuntu-latest, windows-latest, macos-12, macos-14]
+        platform: [ubuntu-latest, windows-latest, macos-13, macos-14]
 
     steps:
       - name: Checkout source
@@ -23,7 +23,7 @@ jobs:
           submodules: recursive
 
       - name: Set up Conda
-        uses: conda-incubator/setup-miniconda@v3.0.4
+        uses: conda-incubator/setup-miniconda@v3.1.0
         with:
             channels: conda-forge
             miniforge-version: latest
@@ -45,7 +45,7 @@ jobs:
 
       - name: Install clang
         shell: "bash -l {0}"
-        if: matrix.platform == 'macos-12'
+        if: matrix.platform == 'macos-13'
         run: |
           conda activate env
           conda install -y 'clang>=12.0.1,<17'
@@ -64,11 +64,11 @@ jobs:
           python -m pip install -v -e .[test,test_extras,msgpack,crc32c]
 
       - name: Install pcodec
-        if: matrix.python-version != '3.13.0'
+        if: matrix.python-version != '3.13'
         shell: "bash -l {0}"
         run: |
             conda activate env
-            python -m pip install -v pcodec
+            python -m pip install -v ".[pcodec]"
 
 
       - name: Install zarr-python
@@ -80,7 +80,7 @@ jobs:
 
       # This is used to test with zfpy, which does not yet support numpy 2.0
       - name: Install older numpy and zfpy
-        if: matrix.python-version == '3.10'
+        if: matrix.python-version == '3.11'
         shell: "bash -l {0}"
         run: |
           conda activate env

.github/workflows/wheel.yaml

@@ -13,11 +13,11 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        # macos-12 is an intel runner, macos-14 is a arm64 runner
-        os: [ubuntu-latest, windows-latest, macos-12, macos-14]
+        # macos-13 is an intel runner, macos-14 is a arm64 runner
+        os: [ubuntu-latest, windows-latest, macos-13, macos-14]
     env:
       CIBW_TEST_COMMAND: python -c "import numcodecs"
-      CIBW_BUILD: "cp310-* cp311-* cp312-* cp313-*"
+      CIBW_BUILD: "cp311-* cp312-* cp313-*"
       CIBW_SKIP: "pp* *-musllinux_* *win32 *_i686 *_s390x"
       # note: CIBW_ENVIRONMENT is now set in pyproject.toml
 
@@ -44,7 +44,7 @@ jobs:
       - uses: actions/setup-python@v5
         name: Install Python
         with:
-          python-version: "3.10"
+          python-version: "3.11"
 
       - name: Build sdist
         run: pipx run build --sdist

.pre-commit-config.yaml

@@ -15,7 +15,7 @@ repos:
     - id: debug-statements
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.7.0
+    rev: v0.7.2
     hooks:
     - id: ruff
       args: ["--fix", "--show-fixes"]

docs/release.rst

@@ -15,12 +15,23 @@ Fix
 ~~~
 * Fix in-place mutation of input array in `BitRound`.
   By :user:`Sam Levang <slevang>`, :issue:`608`
+* Fix an issue where importing numcodecs would lock the state of `multiprocessing`
+  and prevent user code to call `multiprocessing.set_start_method("spawn")`
+  subsequently.
+  By :user:`Clément Robert <neutrinoceros>` :issue:`522`
 
 Enhancements
 ~~~~~~~~~~~~
 * Add Crc32c checksum codec
   By :user:`Norman Rzepka <normanrz>`, :issue:`613`.
 
+Maintenance
+~~~~~~~~~~~
+* The minimum supported Python version is now Python 3.11.
+  By :user:`David Stansby <dstansby>`, :issue:`622`
+* The minimum supported numpy version is now 1.24.
+  By :user:`David Stansby <dstansby>`, :issue:`622`
+
 .. _release_0.13.1:
 
 0.13.1

numcodecs/blosc.pyx

@@ -75,12 +75,21 @@ AUTOSHUFFLE = -1
 AUTOBLOCKS = 0
 
 # synchronization
-try:
-    mutex = multiprocessing.Lock()
-except OSError:
-    mutex = None
-except ImportError:
-    mutex = None
+_MUTEX = None
+_MUTEX_IS_INIT = False
+
+def get_mutex():
+    global _MUTEX_IS_INIT, _MUTEX
+    if not _MUTEX_IS_INIT:
+        try:
+            mutex = multiprocessing.Lock()
+        except OSError:
+            mutex = None
+        except ImportError:
+            mutex = None
+        _MUTEX = mutex
+        _MUTEX_IS_INIT = True
+    return _MUTEX
 
 # store ID of process that first loads the module, so we can detect a fork later
 _importer_pid = os.getpid()
@@ -284,7 +293,7 @@ def compress(source, char* cname, int clevel, int shuffle=SHUFFLE,
             # N.B., we are using blosc's global context, and so we need to use a lock
             # to ensure no-one else can modify the global context while we're setting it
             # up and using it.
-            with mutex:
+            with get_mutex():
 
                 # set compressor
                 compressor_set = blosc_set_compressor(cname)
@@ -480,7 +489,7 @@ def _get_use_threads():
     proc = multiprocessing.current_process()
 
     # check if locks are available, and if not no threads
-    if not mutex:
+    if not get_mutex():
         return False
 
     # check for fork

numcodecs/zarr3.py

@@ -4,11 +4,10 @@
 import math
 from dataclasses import dataclass, replace
 from functools import cached_property
-from typing import Any
+from typing import Any, Self
 from warnings import warn
 
 import numpy as np
-from typing_extensions import Self
 
 import numcodecs
 

pyproject.toml

@@ -4,7 +4,7 @@ requires = [
     "setuptools-scm[toml]>=6.2",
     "Cython",
     "py-cpuinfo",
-    "numpy",
+    "numpy>2",
 ]
 build-backend = "setuptools.build_meta"
 
@@ -15,10 +15,9 @@ A Python package providing buffer compression and transformation codecs \
 for use in data storage and communication applications."""
 readme =  "README.rst"
 dependencies = [
-    "numpy>=1.7",
-    "typing_extensions",
+    "numpy>=1.23",
 ]
-requires-python = ">=3.10"
+requires-python = ">=3.11"
 dynamic = [
   "version",
 ]
@@ -69,7 +68,7 @@ zfpy = [
     "numpy<2.0.0",
 ]
 pcodec = [
-    "pcodec>=0.2.0",
+    "pcodec>=0.2,<0.3",
 ]
 crc32c = [
     "crc32c>=2.7",