[MaulingMonkey]

> File descriptors are a limited resource, but the limits are huge.

Maybe in the linuxy servery context we're talking about, but I'll note I've encountered EMFILE and ENFILE errors attempting to open a mere couple hundred files on iOS simultaniously. And while my own experience is over a decade old, here's someone hitting those limits this year: https://github.com/bevyengine/bevy/pull/17377

(Context for my own encounter: gamedev, with massively parallel asset streaming and multiple layers of direct blocking dependencies in deserialization. One of my hackarounds involved temporarily closing the least recently read files, and then reopening them on demand in our VFS abstraction. Of course, for non-dev builds, you can just use a pack file and `pread` a single fd from multiple threads, but loose files were handy for incremental dev updates...)