Yes. I actually mean both. Thread safety does and doesn't matter. MRI has a GIL so appending to an array across threads will "just work." JRuby doesn't and it w

Yes. I actually mean both. Thread safety does and doesn't matter. MRI has a GIL so appending to an array across threads will "just work." JRuby doesn't and it won't end well if you're not giving it thought. But yeah, multi-process web servers absolutely trample over each other. File access would need to be coordinated / synchronized.