Proposal: release MDNodes for source modules (LTO+debug info)

That is a lot of file descriptors to keep open. It's well above my system's default hard and soft limit, iirc.

I'll try to look at it next week. Deadlines looming!

Just a guess, but it might have something to do with the chrome build
using thin archives.

See: https://sourceware.org/bugzilla/show_bug.cgi?id=15660

See: https://sourceware.org/bugzilla/show_bug.cgi?id=15660

Thanks!

Cheers,
Rafael