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May 6

Add if-unlikely construct?

Hi all, Maybe this has been already discussed or implemented in some way, but I couldn't find

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Add if-unlikely construct?

Hi all, Maybe this has been already discussed or implemented in some way, but I couldn't find

May 6

Peter Schay, da-woods5

Apr 22

python 3.14t crash with a cdef extension module

Great news! Thank you. I can keep on free threading now On Wed, Apr 22, 2026 at 11:36 AM da-woods

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python 3.14t crash with a cdef extension module

Great news! Thank you. I can keep on free threading now On Wed, Apr 22, 2026 at 11:36 AM da-woods

Apr 22

Apr 22

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Apr 22

Vizonex, David Woods2

Apr 3

Segfault with Cython Extension reductable_params during module cleanup

From a quick look, there's one recounting issue in `reduce_call` - PyDict_GetItemWithError`

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Segfault with Cython Extension reductable_params during module cleanup

From a quick look, there's one recounting issue in `reduce_call` - PyDict_GetItemWithError`

Apr 3

Apr 3

Segfault triggered during cleanup on cython 3.2.4

Decided to place this here instead on github as this may be fixable however I don't know. While

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Segfault triggered during cleanup on cython 3.2.4

Decided to place this here instead on github as this may be fixable however I don't know. While

Apr 3

David Meyer, da-woods13

Mar 22

How to Allocate smart pointer scratch space per parallel thread

On 03/03/2026 20:40, da-woods wrote: On 02/03/2026 18:47, David Meyer wrote: I have one final

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How to Allocate smart pointer scratch space per parallel thread

On 03/03/2026 20:40, da-woods wrote: On 02/03/2026 18:47, David Meyer wrote: I have one final

Mar 22

Tobias Diez, Oscar Benjamin3

Mar 19

How to deal with transitive linker dependencies

Thanks Oscar (and sorry for the late response). I suppose some of the issues you mentioned (eg ABI

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How to deal with transitive linker dependencies

Thanks Oscar (and sorry for the late response). I suppose some of the issues you mentioned (eg ABI

Mar 19

vinod kc, da-woods8

Feb 14

Cython is slower than ctypes in win32 based gui

Okay. Thank you for your advice. On Saturday, 14 February 2026 at 15:09:06 UTC+5:30 D Woods wrote: It

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Cython is slower than ctypes in win32 based gui

Okay. Thank you for your advice. On Saturday, 14 February 2026 at 15:09:06 UTC+5:30 D Woods wrote: It

Feb 14

wintermute _ki, da-woods2

Jan 12

more than one python file im a resulting shared library

Hi, Cython is essentially built around the model of "one source file"->"one shared

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more than one python file im a resulting shared library

Hi, Cython is essentially built around the model of "one source file"->"one shared

Jan 12

Michael Williamson, da-woods5

12/22/25

Assertion failed: refcnt >= 0 when importing Cython module compiled with mingw32 for 32-bit Windows

Thanks, both for digging out the information, and for making me aware of pypinfo. On Sunday, December

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Assertion failed: refcnt >= 0 when importing Cython module compiled with mingw32 for 32-bit Windows

Thanks, both for digging out the information, and for making me aware of pypinfo. On Sunday, December

12/22/25

12/10/25

Can't build anymore my Cython programs with Visual Studio 2026

Hi, I have been building my Cython programs for years with Visual Studio 2022, without any problem.

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Can't build anymore my Cython programs with Visual Studio 2026

Hi, I have been building my Cython programs for years with Visual Studio 2022, without any problem.

12/10/25

Wei-Ting Lin, Jérôme Kieffer3

12/5/25

Jupyter notebook needs to import all modules for each cell

Thank you. I got it. Wei-Ting On Friday, November 21, 2025 at 12:49:24 AM UTC-6 Jerome Kieffer wrote:

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Jupyter notebook needs to import all modules for each cell

Thank you. I got it. Wei-Ting On Friday, November 21, 2025 at 12:49:24 AM UTC-6 Jerome Kieffer wrote:

12/5/25

Fredrik Bondesson, da-woods4

11/27/25

Difference between Cython 3.2.0 and 3.1.6?

Thanks for the information! Regards Fredrik onsdag 26 november 2025 kl. 20:04:32 UTC+1 skrev D Woods:

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Difference between Cython 3.2.0 and 3.1.6?

Thanks for the information! Regards Fredrik onsdag 26 november 2025 kl. 20:04:32 UTC+1 skrev D Woods:

11/27/25

Adam Li, … Salih Ahmed4

11/25/25

Performance impact of passing around reshaped memory views of the same underlying array

Dear Adam Li, Please accept my apologies for the delayed response — I was away for a while and couldn

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Performance impact of passing around reshaped memory views of the same underlying array

Dear Adam Li, Please accept my apologies for the delayed response — I was away for a while and couldn

11/25/25

Didier VEZINET, … Jérôme Kieffer16

11/14/25

Transition from setup.py to pyproject.toml only, with dynamic args to cythonize

Thanks Oscar and Jerome, Really helps ! So I've implemented the scipy solution, which presumably

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Transition from setup.py to pyproject.toml only, with dynamic args to cythonize

Thanks Oscar and Jerome, Really helps ! So I've implemented the scipy solution, which presumably

11/14/25

David Lawson, da-woods2

11/11/25

Cython 3.2 - Function signature does not match previous declaration

That's a bug - I've just made a PR for a fix. On 11/11/2025 09:08, David Lawson wrote: I'

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Cython 3.2 - Function signature does not match previous declaration

That's a bug - I've just made a PR for a fix. On 11/11/2025 09:08, David Lawson wrote: I'

11/11/25

Bernie Roesler, da-woods3

11/7/25

"Tuples" of fused types

That works! Thanks. On Nov 5, 2025, at 15:35, da-woods <dw-...@d-woods.co.uk> wrote: You might

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"Tuples" of fused types

That works! Thanks. On Nov 5, 2025, at 15:35, da-woods <dw-...@d-woods.co.uk> wrote: You might

11/7/25

11/3/25

help with struct arrays and buffer formats

Hi again; I managed to get something ultra-simple working which is just fine for my purposes. This

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help with struct arrays and buffer formats

Hi again; I managed to get something ultra-simple working which is just fine for my purposes. This

11/3/25

Muhammad Hawash, da-woods2

10/30/25

Using Cython CFLAGS to enable some feature

In the past I've found that "set" (https://learn.microsoft.com/en-us/windows-server/

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Using Cython CFLAGS to enable some feature

In the past I've found that "set" (https://learn.microsoft.com/en-us/windows-server/

10/30/25

Nils Bruin, … Matthias Koeppe12

10/26/25

Dealing with python version differences across cythonization/compilation/runtime

On Sat, Oct 25, 2025 at 3:17 PM Nils Bruin <bruin...@gmail.com> wrote: > in principle it

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Dealing with python version differences across cythonization/compilation/runtime

On Sat, Oct 25, 2025 at 3:17 PM Nils Bruin <bruin...@gmail.com> wrote: > in principle it

10/26/25

da-woods, Johannes Fischer2

10/23/25

Parallel Programming and Cython talk

I have just watched it. Awesome talk! D Woods schrieb am Dienstag, 21. Oktober 2025 um 15:27:05 UTC-3

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Parallel Programming and Cython talk

I have just watched it. Awesome talk! D Woods schrieb am Dienstag, 21. Oktober 2025 um 15:27:05 UTC-3

10/23/25

аbebus, … Stefan Behnel5

10/18/25

Question about specialization logic for object types in Cython codebase/Cython compiler optimisations

Thanks a lot for the detailed explanation, that's very helpful. I'll definitely benchmark

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Question about specialization logic for object types in Cython codebase/Cython compiler optimisations

Thanks a lot for the detailed explanation, that's very helpful. I'll definitely benchmark

10/18/25

ian macharia, da-woods2

10/13/25

Kivymd app crashing when building kivy on google colab

I've replied on the Github issue that you also posted (https://github.com/cython/cython/issues/

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Kivymd app crashing when building kivy on google colab

I've replied on the Github issue that you also posted (https://github.com/cython/cython/issues/

10/13/25

whoami730, da-woods2

10/2/25

C-style characters

They will get translated into a character literal in C (ie ' '). I don't think we have a

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C-style characters

They will get translated into a character literal in C (ie ' '). I don't think we have a

10/2/25

白隽, da-woods4

9/19/25

cython multithread behavior

Finally,I used with nogil: FspFileSystemStopDispatcher() That's useful! da-woods <dw-git@d-

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cython multithread behavior

Finally,I used with nogil: FspFileSystemStopDispatcher() That's useful! da-woods <dw-git@d-

9/19/25

Mriswithe, da-woods3

9/7/25

Fixing types on the Python side.

I will poke around and see what I can find then. On Sun, Sep 7, 2025, 1:57 PM da-woods <dw-git@d-

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Fixing types on the Python side.

I will poke around and see what I can find then. On Sun, Sep 7, 2025, 1:57 PM da-woods <dw-git@d-

9/7/25

Takeshi Ikuma, da-woods2

9/3/25

Converting fixed-size C pointer to memoryview in the pure Python mode

I think this is a known issue unfortunately and I'm not sure there's a good workaround: https

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Converting fixed-size C pointer to memoryview in the pure Python mode

I think this is a known issue unfortunately and I'm not sure there's a good workaround: https

9/3/25

dg pb, Stefan Behnel4

9/2/25

object's ob_item

dg pb schrieb am 02.09.25 um 21:39: >> On 2 Sep 2025, at 18:21, 'Stefan Behnel' via

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object's ob_item

dg pb schrieb am 02.09.25 um 21:39: >> On 2 Sep 2025, at 18:21, 'Stefan Behnel' via

9/2/25

Ray Speth, da-woods2

9/1/25

Support for combining multiple PYX files in a single module

Hi Ray, As far as possible, everything internal with Cython (ie things we define starting with `

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Support for combining multiple PYX files in a single module

Hi Ray, As far as possible, everything internal with Cython (ie things we define starting with `

9/1/25

Idan Ahal, … David Woods4

8/6/25

Is it possible to use language level 2 with python 3.12?

I'm not sure what a "missing micro" is. However, language_level=2 does still work. The

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Is it possible to use language level 2 with python 3.12?

I'm not sure what a "missing micro" is. However, language_level=2 does still work. The

8/6/25

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