I don't get how it could run out of memory. I was working with over 9 billion results and counting over a course of nearly 3 days on the first shakedown pass. This latest pass didnt even get to 2 billion in 12 hours and it was killed. I got 44 gigs of RAM on this thing, how could it run out of memory?
I ran it again starting last night, and it crashed in the exact same place and same time, just over 1 billion results 15 hours in. "killed214264"
Unfortunately btcrecover doesn't have feature to allocate memory based on available RAM. Have you tried using these parameter to prevent OOM?
--no-dupchecks --no-eta flags