mongodb/mongo — pull request #888 by changyy (2014-12-20 09:17:08+00:00)
Title: Checks the emit in-memory usage in mapper.

The mapper may generate lots of items and each item is kept in-memory at this state. It would be crashed when run out of memory.

NOTE: Skip the checking when using v8 engine (_jsMode: true). The best way is checking at emit function and transfers in memory storage to temp collection. Current state is checking at each document handled because the framework flow designed.