May 11, 2026

#479 Talking About Types

35 minutes

Topics covered in this episode:

httpxyz one month in

Learn concurrency - a deep dive into multithreading with Python

pip 26.1 - lockfiles and dependency cooldowns

Python 3.15 sentinal values from PEP 661

Extras

Joke

Watch on YouTube

About the show

Sponsored by us! Support our work through:

Our courses at Talk Python Training

The Complete pytest Course

Patreon Supporters

Connect with the hosts

Michael: @[email protected] / @mkennedy.codes (bsky)

Brian: @[email protected] / @brianokken.bsky.social

Show: @[email protected] / @pythonbytes.fm (bsky)

Join us on YouTube at pythonbytes.fm/live to be part of the audience. Usually Monday at 11am PT. Older video versions available there too.

Finally, if you want an artisanal, hand-crafted digest of every week of the show notes in email form? Add your name and email to our friends of the show list, we'll never share it.

Michael #1: httpxyz one month in

First version of httpxyz contained just the fixes to get zstd working, and the fixes to get the test suite running on python 3.14, some ‘housekeeping’ changes related to the renaming

End of March: a compatibility shim that allows you to use httpxyz even with third-party packages that import httpx themselves, as long as you import httpxyz first.

Importing httpxyz automatically registers it under the httpx name in sys.modules , see https://httpxyz.org/httpx-compatibility/

Fixed a WHOLE bunch of performance related issues by forking httpcore

Brian #2: Learn concurrency - a deep dive into multithreading with Python

Nikos Vaggalis

“Whenever you are trying to speed up code using multiple cores, always ask yourself: “Do these threads need to talk to each other right now?” If the answer is yes, it will be slow. The best parallel code splits a big job into completely isolated chunks, processes them separately, and merges the results at the finish line.”

Good overview of thread concurrency with Python and how that’s been improved dramatically with free-threaded Python

Defines lots of terms you come across, including “embarrassingly parallel multithreading”

There’s a counter example that’s nice

Start with a shared resource, a counter, and multiple threads updating it

Attempt to fix with threading.Lock(), which fixes it, but slows things down

Good explanation of why

Proper fix with concurrent.futures and separating the work of different threads so that they can be independent and their results can be combined when they’re all finished.

Michael #3: pip 26.1 - lockfiles and dependency cooldowns

Python 3.9 is no longer supported

Experimental: installing from pylock files

Dependency cooldowns (see my post about this)

Lifting several 2020 resolver limitations

Brian #4: Python 3.15 sentinal values from PEP 661

MISSING = sentinel("MISSING")

def next_value(default: int | MISSING = MISSING):

...

if default is MISSING:

...

Take a name str as a constructor parameter

Intended to be compared with is operator, similar to None

Sentinal objects can be used as a type, also similar to None

and can be combined with other types with |.

Unlike None, sentinal values are truthy. (Elipses ... are also truthy)

This seems like a strange choice. but I guess it must have made sense to someone.

It does force you to use is instead of depending on False-ness, so I guess it’ll make code using sentinels more readable.

Interesting that the PEP was started in 2021, and we’re finally getting it this year.

Extras

Brian:

Before GitHub - Armin Ronacher

tenacity - cross-platform multi-track audio editor/recorder

learned about it from Armin’s article

Joke:

Joke option Make it myself

Seems similar to what people think about software now

Links

httpxyz one month in

httpxyz.org/httpx-compatibility

Learn concurrency - a deep dive into multithreading with Python

pip 26.1 - lockfiles and dependency cooldowns

my post about this

Python 3.15 sentinal values from PEP 661

Before GitHub

tenacity

Make it myself

...more

View all episodes

By Michael Kennedy and Brian Okken

4.7

212212 ratings

May 11, 2026

#479 Talking About Types

35 minutes

Topics covered in this episode:

httpxyz one month in

Learn concurrency - a deep dive into multithreading with Python

pip 26.1 - lockfiles and dependency cooldowns

Python 3.15 sentinal values from PEP 661

Extras

Joke

Watch on YouTube

About the show

Sponsored by us! Support our work through:

Our courses at Talk Python Training

The Complete pytest Course

Patreon Supporters

Connect with the hosts

Michael: @[email protected] / @mkennedy.codes (bsky)

Brian: @[email protected] / @brianokken.bsky.social

Show: @[email protected] / @pythonbytes.fm (bsky)

Join us on YouTube at pythonbytes.fm/live to be part of the audience. Usually Monday at 11am PT. Older video versions available there too.

Finally, if you want an artisanal, hand-crafted digest of every week of the show notes in email form? Add your name and email to our friends of the show list, we'll never share it.

Michael #1: httpxyz one month in

First version of httpxyz contained just the fixes to get zstd working, and the fixes to get the test suite running on python 3.14, some ‘housekeeping’ changes related to the renaming

End of March: a compatibility shim that allows you to use httpxyz even with third-party packages that import httpx themselves, as long as you import httpxyz first.

Importing httpxyz automatically registers it under the httpx name in sys.modules , see https://httpxyz.org/httpx-compatibility/

Fixed a WHOLE bunch of performance related issues by forking httpcore

Brian #2: Learn concurrency - a deep dive into multithreading with Python

Nikos Vaggalis

Good overview of thread concurrency with Python and how that’s been improved dramatically with free-threaded Python

Defines lots of terms you come across, including “embarrassingly parallel multithreading”

There’s a counter example that’s nice

Start with a shared resource, a counter, and multiple threads updating it

Attempt to fix with threading.Lock(), which fixes it, but slows things down

Good explanation of why

Proper fix with concurrent.futures and separating the work of different threads so that they can be independent and their results can be combined when they’re all finished.

Michael #3: pip 26.1 - lockfiles and dependency cooldowns

Python 3.9 is no longer supported

Experimental: installing from pylock files

Dependency cooldowns (see my post about this)

Lifting several 2020 resolver limitations

Brian #4: Python 3.15 sentinal values from PEP 661

MISSING = sentinel("MISSING")

def next_value(default: int | MISSING = MISSING):

...

if default is MISSING:

...

Take a name str as a constructor parameter