# Are all descriptions of the "caveats", listed near the end of \_thread module's docs, up to date?

**URL:** <https://discuss.python.org/t/are-all-descriptions-of-the-caveats-listed-near-the-end-of-thread-modules-docs-up-to-date/55261>\
**Category:** Python Help\
**Created:** [June 8, 2024, 8:34pm UTC](https://discuss.python.org/t/are-all-descriptions-of-the-caveats-listed-near-the-end-of-thread-modules-docs-up-to-date/55261 "2024-06-08T20:34:20Z")\
**Posts on this page:** 1\
**Showing post:** 18

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**Author:** ![eryksun](https://sea2.discourse-cdn.com/flex002/user_avatar/discuss.python.org/eryksun/32/697_2.png) [@eryksun](https://discuss.python.org/u/eryksun)\
**Post date:** [June 11, 2024, 10:19am UTC](https://discuss.python.org/t/are-all-descriptions-of-the-caveats-listed-near-the-end-of-thread-modules-docs-up-to-date/55261/18 "2024-06-11T10:19:28Z")

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> [@zuo](#):
>
> Are there any platforms for which `_threads` is available and `signal` is not?

The `signal` module should always be available on the currently supported platforms. Note that on Windows, the C runtime library just emulates a few signals, since Windows does not implement POSIX signals\[1\].

> [@zuo](#):
>
> - When the main thread exits, it does not do any of its usual cleanup (except that [`try`](https://docs.python.org/3/reference/compound_stmts.html#try) … [`finally`](https://docs.python.org/3/reference/compound_stmts.html#finally) clauses are honored), and the standard I/O files are not flushed.

That’s not right. If the main thread exits normally back to `Py_RunMain()` or if it raises `SystemExit`, then `Py_FinalizeEx()` gets called, which, among other things, shuts down the `threading` module and calls Python `atexit` functions. If the process exits via C `exit()` or `_exit()`, then `Py_FinalizeEx()` isn’t called, so `threading` isn’t shut down and Python `atexit` functions aren’t called.

* * *

1. `SIGBREAK` and `SIGINT` are based on the corresponding console control events. `SIGSEGV`, `SIGILL`, and `SIGFPE` are based on the corresponding OS exceptions. `SIGABRT` and `SIGTERM` are emulated just for use with C `raise()` and `abort()`. There isn’t support in Python for handling `SIGSEGV`, `SIGILL`, `SIGFPE`, and `SIGABRT` due to the design of the C signal handler, which just sets a flag and returns. Also, handling `SIGINT` and `SIGBREAK` is broken when reading from the console/terminal since `EOFError` is raised instead of restarting the read.

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