WIP 3.14t support

.github/workflows/tests.yaml

@@ -26,7 +26,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        environment: [mindeps, "3.10", "3.11", "3.12", "3.13", "3.14"]
+        environment: [mindeps, "3.10", "3.11", "3.12", "3.13", "3.14", "3.14t"]
         label: [default]
         extra_packages: [null]
         # Cherry-pick test modules to split the overall runtime roughly in half
@@ -44,6 +44,8 @@ jobs:
             environment: "3.12"
           - os: macos-latest
             environment: "3.13"
+          - os: macos-latest
+            environment: "3.14t"
 
           - os: windows-latest
             environment: mindeps
@@ -180,6 +182,29 @@ jobs:
         shell: bash -l {0}
         run: conda install -y ${{ join(matrix.extra_packages, ' ') }}
 
+      - name: Disable msgpack C extension on free-threading
+        # FIXME https://github.com/msgpack/msgpack-python/issues/613
+        # The msgpack C module does not contain any race conditions in free-threading,
+        # but does not release the GIL. So we need to either install the (slower)
+        # pure-python variant or we need to run the test suite with PYTHON_GIL=0.
+        # The former approach has the benefit of proving that msgpack is the only offender.
+        if: ${{ matrix.environment == '3.14t' }}
+        shell: bash -l {0}        
+        run: |
+          conda uninstall -y -v --force msgpack-python
+          MSGPACK_PUREPYTHON=1 python -m pip install msgpack --no-binary msgpack --no-cache --force-reinstall -v
+          python -Werror -c 'import msgpack'
+
+      - name: Uninstall brotli on free-threading
+        # brotli is an optional dependency of urllib3, but it is pulled in
+        # by the urllib3 conda package.
+        # brotli does not release the GIL, so we need to uninstall it now.
+        if: ${{ matrix.environment == '3.14t' }}
+        shell: bash -l {0}        
+        run: |
+          conda uninstall -y -v --force brotli-python
+          python -Werror -c 'import urllib3'
+
       - name: Install
         shell: bash -l {0}
         run: |

continuous_integration/environment-3.14t.yaml

@@ -0,0 +1,56 @@
+name: dask-distributed
+channels:
+  - conda-forge
+dependencies:
+  - python-freethreading=3.14
+  - packaging
+  - pip
+  - asyncssh
+  - bokeh>3
+  - click
+  - cloudpickle
+  - coverage
+  - dask  # overridden by git tip below; pulls in optional dependencies
+  - fsspec  # overridden by git tip below
+  # - gilknocker  # Makes no sense in free-threading
+  - h5py
+  # - ipykernel  # No 3.14t build for Windows yet
+  - ipywidgets
+  - jinja2
+  - jupyter_events
+  # - jupyter-server-proxy  # No ipykernel 3.14t for Windows yet
+  # - jupyterlab  # No ipykernel 3.14t for Windows yet
+  - locket
+  # FIXME https://github.com/msgpack/msgpack-python/issues/613
+  # tests.yml replaces this with a pure-python variant.
+  - msgpack-python
+  - netcdf4
+  - paramiko
+  - pre-commit
+  - prometheus_client
+  - psutil
+  - pyarrow
+  - pytest
+  - pytest-cov
+  - pytest-faulthandler
+  - pytest-repeat
+  - pytest-rerunfailures
+  - pytest-timeout
+  # FIXME requests depends on urllib3, which in turn (only in conda) installs optional
+  # dependency brotli, which does not release the GIL.
+  # tests.yaml force-uninstalls brotli to work around this.
+  - requests
+  - scikit-learn
+  - scipy
+  - setproctitle
+  - sortedcollections
+  - tblib
+  - toolz
+  - tornado
+  - zict  # overridden by git tip below
+  - zstandard
+  - pip:
+      - git+https://github.com/dask/dask
+      - git+https://github.com/dask/zict
+      - git+https://github.com/fsspec/filesystem_spec
+      - keras

pyproject.toml

@@ -21,6 +21,7 @@ classifiers = [
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
     "Programming Language :: Python :: 3.14",
+    "Programming Language :: Python :: Free Threading :: 1 - Unstable",
     "Topic :: Scientific/Engineering",
     "Topic :: System :: Distributed Computing",
 ]