out of memory crash when compacting document with lots of edit branches

I have a database which will crash CouchDB if I try to compact it. It causes beam.smp to use all the memory on the server. I caught it in the act one time and sorted the Erlang processes by memory usage. The process spawned to do the compaction turned out to be the culprit. I took a backtrace of the process and found that it was mapping a very large revision tree. I have reason to believe that the document has a large number (~1000s) of edit conflicts.

I think part of the problem may be that the recursion in couch_key_tree:map_simple requires each stack space for every iteration. I'm not sure if it's possible to rewrite the algorithm in a more memory-friendly way given the current tree structure.