how to debug when server hangs?

Hi,

Occasionally, as I'm developing new Ruby code in my .rhtml page, the
server hangs indefinitely when I try to request a page.  I'm sure it's
because of my own bug, but how can I begin to debug this?

The only way I know of is to restart the whole Apache server, comment
out half my new code at a time, and in a kind of binary search,
eventually figure out what's causing the problem.  And that, of
course, is only in the case where it's repeatable; sometimes I get a
Heisen-bug that just shows up once in a while.

Is there any other way?

Cheers,
 - arb