evan

[...] When you have that much memory it's difficult to actually make use of all of it from a language like JavaScript because it's single-threaded. That is, the time it takes to read in and out (or more importantly, process) that much data starts making apps that would use more data unuseful. He suggested that part of the reason 64-bit Java was important was that there were these heavyweight servers with multiple cores that wanted to run a bunch of Java threads in the same heap simultaneously.

There's an interesting parallel here to servers. Say you can stick 10 terabytes of disk in a single machine -- it ends up not being too useful as a server unless it's archival, as in most of that data isn't accessed, because you're ultimately limited by disk bandwidth. Just trying to stream the contents of the disks at a sequential 50mb/sec** would take two and a half days. So when you're trying to serve real-time data off a disk (like, say, a search engine might) you're better off having more machines with smaller disks.