MatLab and virtual memory... Who leaked on my disk?

I ran a big job over the weekend, and got back to work this morning to find it was (quite unexpectedly) only 25% complete. Since it naievely dumps its results only after completion, I lost the whole weekend.

Pulling up task manager, I checked out my RAM usage: flat-line 5 out of 8 GB. No problem. CPU was piddley - should have been up about 98% across the dash. The system "commit charge" was sitting at 23 GB. I had four extra MatLab processes (due to Parallel Toolbox), each having clocked up TWO BILLION page faults. The delta showed between 5000 and 10000 faults per second on each.

I terminated the master MatLab process, and the "commit charge" emptied out 20 GB of surplus pages.

My batch job does not hold onto any data. It preallocates everything, and then laboriously fills the gaps.

Does anyone know what could be going on here? It seems like a whole lot of memory is leaking out to disk, while MatLab's memory usage remains pretty constant. I've read before about small memory allocations not being returned correctly to the OS. Maybe that's what's going on here?

I'm doing a lot of database queries, loading models from .mat files, and doing nothing else interesting apart from crunching numbers. This sort of behaviour is highly unexpected. I'm used to handling huge datasets, but it seems when I do it with MatLab I run into a lot of problems.