From 61698587d22014a99c22b4f63f12fe900028b843 Mon Sep 17 00:00:00 2001
From: crusaderky <crusaderky@gmail.com>
Date: Fri, 13 Feb 2026 12:12:49 +0000
Subject: [PATCH 1/4] 3.14t support

---
 .github/workflows/tests.yaml                  | 17 +++-
 continuous_integration/environment-3.10.yaml  |  2 +-
 continuous_integration/environment-3.11.yaml  |  2 +-
 continuous_integration/environment-3.12.yaml  |  2 +-
 continuous_integration/environment-3.13.yaml  |  4 +-
 continuous_integration/environment-3.14.yaml  |  4 +-
 continuous_integration/environment-3.14t.yaml | 79 +++++++++++++++++++
 pyproject.toml                                |  1 +
 8 files changed, 103 insertions(+), 8 deletions(-)
 create mode 100644 continuous_integration/environment-3.14t.yaml

diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index 2aa9f94282e..80d5f2c756c 100644
--- a/.github/workflows/tests.yaml
+++ b/.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
@@ -168,6 +170,19 @@ jobs:
             || steps.cache.outputs.cache-hit != 'true'
           )
 
+      - 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: Install
         shell: bash -l {0}
         run: |
diff --git a/continuous_integration/environment-3.10.yaml b/continuous_integration/environment-3.10.yaml
index f3914e8ae9a..4ab79b4bda1 100644
--- a/continuous_integration/environment-3.10.yaml
+++ b/continuous_integration/environment-3.10.yaml
@@ -13,7 +13,7 @@ dependencies:
   - cloudpickle
   - coverage
   - cython  # Only tested here; also a dependency of crick
-  - dask  # overridden by git tip below
+  - dask  # overridden by git tip below; pulls in optional dependencies
   - fsspec
   - gilknocker
   - h5py
diff --git a/continuous_integration/environment-3.11.yaml b/continuous_integration/environment-3.11.yaml
index 256999899d1..e611e21dc3d 100644
--- a/continuous_integration/environment-3.11.yaml
+++ b/continuous_integration/environment-3.11.yaml
@@ -11,7 +11,7 @@ dependencies:
   - click
   - cloudpickle
   - coverage
-  - dask  # overridden by git tip below
+  - dask  # overridden by git tip below; pulls in optional dependencies
   - fsspec  # overridden by git tip below
   - gilknocker
   - h5py
diff --git a/continuous_integration/environment-3.12.yaml b/continuous_integration/environment-3.12.yaml
index e33c82a30e9..6c8a15708cb 100644
--- a/continuous_integration/environment-3.12.yaml
+++ b/continuous_integration/environment-3.12.yaml
@@ -11,7 +11,7 @@ dependencies:
   - click
   - cloudpickle
   - coverage
-  - dask  # overridden by git tip below
+  - dask  # overridden by git tip below; pulls in optional dependencies
   - fsspec  # overridden by git tip below
   - gilknocker
   - h5py
diff --git a/continuous_integration/environment-3.13.yaml b/continuous_integration/environment-3.13.yaml
index 3e22fa4b466..f50495ffd44 100644
--- a/continuous_integration/environment-3.13.yaml
+++ b/continuous_integration/environment-3.13.yaml
@@ -1,4 +1,4 @@
-name: dask-distributed-313
+name: dask-distributed
 channels:
   - conda-forge
 dependencies:
@@ -10,7 +10,7 @@ dependencies:
   - click
   - cloudpickle
   - coverage
-  - dask  # overridden by git tip below
+  - dask  # overridden by git tip below; pulls in optional dependencies
   - fsspec  # overridden by git tip below
   - gilknocker
   - h5py
diff --git a/continuous_integration/environment-3.14.yaml b/continuous_integration/environment-3.14.yaml
index b39f35c9d08..7156631a4b3 100644
--- a/continuous_integration/environment-3.14.yaml
+++ b/continuous_integration/environment-3.14.yaml
@@ -1,4 +1,4 @@
-name: dask-distributed-313
+name: dask-distributed
 channels:
   - conda-forge
 dependencies:
@@ -10,7 +10,7 @@ dependencies:
   - click
   - cloudpickle
   - coverage
-  - dask  # overridden by git tip below
+  - dask  # overridden by git tip below; pulls in optional dependencies
   - fsspec  # overridden by git tip below
   - gilknocker
   - h5py
diff --git a/continuous_integration/environment-3.14t.yaml b/continuous_integration/environment-3.14t.yaml
new file mode 100644
index 00000000000..43f9ddf783e
--- /dev/null
+++ b/continuous_integration/environment-3.14t.yaml
@@ -0,0 +1,79 @@
+name: dask-distributed
+channels:
+  - conda-forge
+dependencies:
+  - python-freethreading=3.14
+  - packaging
+  - pip
+  - asyncssh
+  - bokeh>3
+  - click
+  - cloudpickle
+  - coverage
+  # conda variant of dask depends on cytoolz, which is not available
+  # on conda yet. Manually install dask dependencies from conda below.
+  # - dask  # overridden by git tip below; pulls in optional dependencies
+  - fsspec  # overridden by git tip below
+  # - gilknocker  # Makes no sense in free-threading
+  # - h5py  # Not available for 3.14t
+  # - ipykernel  # Not available for 3.14t
+  - ipywidgets
+  - jinja2
+  - jupyter_events
+  # - jupyter-server-proxy  # Not available for 3.14t
+  # - jupyterlab  # Not available for 3.14t
+  - locket
+  # FIXME https://github.com/msgpack/msgpack-python/issues/613
+  # Install placeholder to prevent distributed below from compiling the C extension from
+  # sources. tests.yml will replace 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
+  - requests
+  - scikit-learn
+  - scipy
+  - sortedcollections
+  - tblib
+  - toolz
+  - tornado
+  - zict  # overridden by git tip below
+  - zstandard
+
+  ##### 3.14t temporary hacks
+  # packages normally pulled in by the `dask` conda package
+  - dask-core
+  # - cytoolz  # conda package for 3.14t not yet available; installed via pip below
+  - lz4
+  - numpy
+  - pandas>=3  # Actually need >=3.0.1 due to severe race conditions in 3.0
+               # (https://github.com/pandas-dev/pandas/pull/63783)
+               # Until 3.0.1 is released, this is temporarily overridden
+               # by pandas git below.
+  - pyarrow
+  - bokeh
+  - jinja2
+  - pyyaml
+  - sortedcontainers
+  - urllib3
+  ##### end 3.14t hacks
+
+  - pip:
+      - git+https://github.com/dask/dask
+      - git+https://github.com/dask/zict
+      - git+https://github.com/fsspec/filesystem_spec
+      - keras
+
+      ##### 3.14t temporary hacks
+      - cytoolz  # conda package for 3.14t not yet available
+      - git+https://github.com/pandas-dev/pandas.git@3.0.x  # Need pandas 3.0.1
+      ##### end 3.14t hacks
diff --git a/pyproject.toml b/pyproject.toml
index 280c04923cd..c6652eee21c 100644
--- a/pyproject.toml
+++ b/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",
 ]

From e48a573c661e3e9fb33e1c0c8738adb66b556da4 Mon Sep 17 00:00:00 2001
From: crusaderky <crusaderky@gmail.com>
Date: Tue, 28 Apr 2026 16:08:32 +0100
Subject: [PATCH 2/4] Remove environment hacks

---
 continuous_integration/environment-3.14t.yaml | 40 ++++---------------
 1 file changed, 7 insertions(+), 33 deletions(-)

diff --git a/continuous_integration/environment-3.14t.yaml b/continuous_integration/environment-3.14t.yaml
index 43f9ddf783e..e4da9f8ecb6 100644
--- a/continuous_integration/environment-3.14t.yaml
+++ b/continuous_integration/environment-3.14t.yaml
@@ -10,22 +10,19 @@ dependencies:
   - click
   - cloudpickle
   - coverage
-  # conda variant of dask depends on cytoolz, which is not available
-  # on conda yet. Manually install dask dependencies from conda below.
-  # - dask  # overridden by git tip below; pulls in optional dependencies
+  - dask  # overridden by git tip below; pulls in optional dependencies
   - fsspec  # overridden by git tip below
   # - gilknocker  # Makes no sense in free-threading
-  # - h5py  # Not available for 3.14t
-  # - ipykernel  # Not available for 3.14t
+  - h5py
+  - ipykernel
   - ipywidgets
   - jinja2
   - jupyter_events
-  # - jupyter-server-proxy  # Not available for 3.14t
-  # - jupyterlab  # Not available for 3.14t
+  - jupyter-server-proxy
+  - jupyterlab
   - locket
   # FIXME https://github.com/msgpack/msgpack-python/issues/613
-  # Install placeholder to prevent distributed below from compiling the C extension from
-  # sources. tests.yml will replace this with a pure-python variant.
+  # tests.yml replaces this with a pure-python variant.
   - msgpack-python
   - netcdf4
   - paramiko
@@ -42,38 +39,15 @@ dependencies:
   - requests
   - scikit-learn
   - scipy
+  - setproctitle
   - sortedcollections
   - tblib
   - toolz
   - tornado
   - zict  # overridden by git tip below
   - zstandard
-
-  ##### 3.14t temporary hacks
-  # packages normally pulled in by the `dask` conda package
-  - dask-core
-  # - cytoolz  # conda package for 3.14t not yet available; installed via pip below
-  - lz4
-  - numpy
-  - pandas>=3  # Actually need >=3.0.1 due to severe race conditions in 3.0
-               # (https://github.com/pandas-dev/pandas/pull/63783)
-               # Until 3.0.1 is released, this is temporarily overridden
-               # by pandas git below.
-  - pyarrow
-  - bokeh
-  - jinja2
-  - pyyaml
-  - sortedcontainers
-  - urllib3
-  ##### end 3.14t hacks
-
   - pip:
       - git+https://github.com/dask/dask
       - git+https://github.com/dask/zict
       - git+https://github.com/fsspec/filesystem_spec
       - keras
-
-      ##### 3.14t temporary hacks
-      - cytoolz  # conda package for 3.14t not yet available
-      - git+https://github.com/pandas-dev/pandas.git@3.0.x  # Need pandas 3.0.1
-      ##### end 3.14t hacks

From 9ecc9fabc440f1c7deafea1eff087002e2fa1e36 Mon Sep 17 00:00:00 2001
From: crusaderky <crusaderky@gmail.com>
Date: Tue, 28 Apr 2026 17:38:08 +0100
Subject: [PATCH 3/4] revert

---
 continuous_integration/environment-3.14t.yaml | 23 ++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/continuous_integration/environment-3.14t.yaml b/continuous_integration/environment-3.14t.yaml
index e4da9f8ecb6..89c1825cf8d 100644
--- a/continuous_integration/environment-3.14t.yaml
+++ b/continuous_integration/environment-3.14t.yaml
@@ -10,7 +10,11 @@ dependencies:
   - click
   - cloudpickle
   - coverage
-  - dask  # overridden by git tip below; pulls in optional dependencies
+  # This pulls in a dependency chain (specific to conda)
+  # dask -> distributed -> urllib3 -> brotli
+  # and brotli does not release the GIL.
+  # Manually install dask dependencies from conda below.
+  # - dask  # overridden by git tip below; pulls in optional dependencies
   - fsspec  # overridden by git tip below
   # - gilknocker  # Makes no sense in free-threading
   - h5py
@@ -46,6 +50,23 @@ dependencies:
   - tornado
   - zict  # overridden by git tip below
   - zstandard
+
+  ##### 3.14t temporary hacks
+  # packages normally pulled in by the `dask` conda package
+  - dask-core
+  - cytoolz
+  - lz4
+  - numpy
+  - pandas >=3.0.1
+  - pyarrow
+  - bokeh
+  - jinja2
+  - pyyaml
+  - sortedcontainers
+  # Uniquely used by preload. Depends on brotli, which does not release the GIL
+  # - urllib3
+  ##### end 3.14t hacks
+
   - pip:
       - git+https://github.com/dask/dask
       - git+https://github.com/dask/zict

From 056ada75246d356f82c74ef7f128482f8ee58304 Mon Sep 17 00:00:00 2001
From: crusaderky <crusaderky@gmail.com>
Date: Tue, 28 Apr 2026 17:40:35 +0100
Subject: [PATCH 4/4] revert

---
 continuous_integration/environment-3.14t.yaml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/continuous_integration/environment-3.14t.yaml b/continuous_integration/environment-3.14t.yaml
index 89c1825cf8d..5a31183a7d0 100644
--- a/continuous_integration/environment-3.14t.yaml
+++ b/continuous_integration/environment-3.14t.yaml
@@ -18,12 +18,12 @@ dependencies:
   - fsspec  # overridden by git tip below
   # - gilknocker  # Makes no sense in free-threading
   - h5py
-  - ipykernel
+  # - ipykernel  # No 3.14t for Windows yet
   - ipywidgets
   - jinja2
   - jupyter_events
-  - jupyter-server-proxy
-  - jupyterlab
+  # - 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.