`logging.shutdown()` should clear `logging._handlerList` if that's what it's called with

Bug report

Bug description:

In the wild, I've encountered situations where logging.shutdown gets called more than once in a process.

The current implementation is called with logging._handlerList by default, meaning that handlers can have their flush() and close() methods called more than once, which can cause bad things to happen if those handlers are not amenable to being closed more than once.

If logging.shutdown() is processing logging._handlerList, it should clear that list once it finished to prevent handlers having their flush() and close() methods called more than once.

CPython versions tested on:

3.12, CPython main branch

Operating systems tested on:

Linux, macOS

Linked PRs

• gh-129681

Beginnen Sie am Einstiegspunkt logging.shutdown() und untersuchen Sie, wie logging._handlerList verarbeitet wird, einschließlich der im Bericht beschriebenen wiederholten Aufrufe von flush() und close(). Bestätigen Sie, dass shutdown die Standard-Handlerliste nach ihrer Verarbeitung leert, und überprüfen Sie, dass wiederholte Aufrufe von shutdown dieselben Handler nicht erneut verarbeiten.