On 10/6/05, Avi Bryant <avi.bryant at gmail.com> wrote:
> How necessary is it to do the GC before a snapshot?

I doubt that anybody knows. If I had been the author of the
snapshotting code, I would have included a GC from the beginning, and
perhaps nobody since then would have had a reason to take it out. (If
you ever have to look at an image file's internals for debugging
reasons, it will be "cleaner" after a GC, for one thing.)

> Is it possible
> to do a writeImageFile() without a GC and safely use the resulting
> image, or does that violate some assumptions somewhere?

An image before a GC should be just as valid as the same image after a
GC. If you find otherwise, it's a bug. Nevertheless, that will be of
little comfort if you find yourself struggling to reconstruct a
working image on a deadline.

My advice, which probably says nothing you didn't already know, is to
make a backup, carefully eyeball the snapshotting code, then give your
idea a try, with lots of testing before you commit to it. I don't see
why it wouldn't work, although moving the GC to happen before the fork
would perhaps solve your memory thrashing problems with fewer worries.

--Tom Phoenix