If you hit an explicit limit, I'd expect the thread spawn to fail, and most processes to panic if thread spawning failed, sure.
But if you run below the explicit limit, but above the implicit limit of whatever continues to work, it's not surprising to me that the OS just freaked out.
You could report it to Apple, but their reporting process is pretty opaque, especially if you're not a registered developer (because why would you be, if you're just using mac os because you like the desktop environment, or whatever). Who knows if they'll fix it, but it's not worth making a big deal over, because you weren't really wanting to run 2k threads on mac os anyway, because it would suck, even if it did work.
From the other message on the thread; it looks like too many threads is causing a watchdog timer to fail, leading to the panic.
I mean, I would expect most OSes to today. If you run a couple thousand threads on windows 10, or Android 10, or a recent Linux or BSD, it's probably fine (ish).
But probably not on Windows 9x, maybe not even on NT4 (although, NT4 was pretty solid), and I wouldn't expect good results on Linux or a BSD from 2000 either.
But macos has lowered my expectations. It's a mash of FreeBSD from the turn of the century, with Mach from earlier, and whatever stuff they've fiddled with since then, plus a nice UI layer. They don't regularly pull in updates from FreeBSD, and the killed their server line (which was mediocre at best anyway), so when it panics if you do something weird, it's not unexpected.
But if you run below the explicit limit, but above the implicit limit of whatever continues to work, it's not surprising to me that the OS just freaked out.
You could report it to Apple, but their reporting process is pretty opaque, especially if you're not a registered developer (because why would you be, if you're just using mac os because you like the desktop environment, or whatever). Who knows if they'll fix it, but it's not worth making a big deal over, because you weren't really wanting to run 2k threads on mac os anyway, because it would suck, even if it did work.
From the other message on the thread; it looks like too many threads is causing a watchdog timer to fail, leading to the panic.