It seems that pthread_setname_np() only works with ASCII names here.

>>> import _thread
>>> _thread.set_name('€')
Traceback (most recent call last):
  File "<python-input-1>", line 1, in <module>
    _thread.set_name('€')
    ~~~~~~~~~~~~~~~~^^^^^
OSError: [Errno 22] Invalid argument

In addition to making the test more lenient, we can make _thread.set_name() more tolerant to such restriction -- use ASCII encoding with the "replace" or "ignore" error handler as a fallback.

cc @vstinner

Linked PRs

• gh-138004: Encode thread names on Solaris-based platforms as ASCII and fix main/worker threading test #138017
• [3.14] gh-138004: Fix setting a thread name on OpenIndiana (GH-138017) #138384