Re^2: Running out of address space? (VM)

[tye]

http://old.nabble.com/malloc-%28error-code%3D12%29-td21596897.html includes the following:

You may have run out of swap space, but that is unlikely.

The most likely cause is that you have run out of address space.

But they don't give any explanation for that conclusion. My experience is that it is much more likely to run out of swap space than to run out of address space. You can have a ton of little things that add up to taking up all available swap space. To run out of address space, the single process has to exceed something close to 4GB.

A 64-bit OS will allow allocation of huge amounts of VM (via malloc) only if you have sufficient free swap space to back the allocated pages.

It appears that OS X just dynamically resizes swap space so "running out of swap space" probably means "running out of disk space" (at least on the partition that contains the swap directory, which might default to /private/var/vm).

It would be useful to use something like 'top' to watch the size of the process in order to determine how big it is really getting before it fails, instead of just guessing.