Memory profile snow2

[ma-sadeghi]

On our 256GB-memory server, I couldn't do extraction for images larger than 1200^3. Given that a 1200^3 image stored in float64 roughly takes up ~14GB of memory, snow2 is using ~18 times that amount, which is not not an order of magnitude off, but I think could be improved 2-3X.

Here are some ideas:

• Maybe we're using float64 in some places where int64 (or even int32) could do the job.
• I don't think the distance transform needs to be exact down 16 digits, so maybe we could use float32 or even float16?

[jgostick]

All good points....but I was able to do a 1100 by 1100 by 2800 on that sever earlier this week. I used [2, 2, 8] as the chunk size.

[ma-sadeghi]

Per the discussion w/ @jgostick, the issue is multiphase extraction. It seems that memory usage builds up.

[jgostick]

Try this: https://github.com/plasma-umass/scalene

[ma-sadeghi]