Victor Stinner

I don't think that there is a "good default behavior" where Python currently calls PyThread_exit_thread(). IMO we should take the problem from the other side and tries to reduce cases...

See also bpo-13077 "Windows: Unclear behavior of daemon threads on main thread exit".

> It looks like the `_thread` module does not actually expose `PyThread_exit_thread` --- the similarly named `thread_PyThread_exit_thread` just raises SystemExit. Oh right, I was confused by the function name: "thread_PyThread_exit_thread()"....

I'm not comfortable with [PR 28525](https://github.com/python/cpython/pull/28525) which always hang threads which attempt to acquire the GIL after Python exited. I would prefer to keep the current behavior by default, but...

> In this case that unexpected thread simply disappearing can lead to a deadlock in our process. This problem also remains me the very complex case of bpo-6721: "Locks in...

Gregory P. Smith: Python has many API using callbacks: PEP-445 added PyMem_SetAllocator() to set memory allocator. Adding PyMem_GetAllocator() also made possible to chain allocators and to "hook" into an existing...

Another example where a developer asks to call abort() to notice bugs, whereas Python previously silently ignored it: bpo-36829. Calling abort() is a legit use case, but not really the...

Jeremy Maitin-Shepard: "In general, I view hanging threads as the least bad thing to do when faced with either acquiring the GIL or not returning at all. There is a...

> Since the 4.0 upgrade, the !buildbot command starts more buildbots than before I saw this issue before, I'm not sure that it's a regression caused by the buildbot 4.0...

> Sounds like https://github.com/python/cpython/issues/121245 reappears. Does this build has readline support? Windows has no readline module.