[AnimalMuppet]

Wait, what? An exception takes out a global lock?

Do you know which runtimes do this? Or, which runtimes don't?

[gpderetta]

libstc++ does. And IIRC the reason is the usual culprit: dlclose [1].

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71744