The AsyncResultsMerger was originally developed by the sharding team, for the purpose of merging multiple, remote cursor streams asynchronously and in parallel. Right now, it is only linked into mongos, but it could useful as a general purpose component if it was made less sharding specific and was able to be accessed from a mongod. One of the intended non-sharding uses of the ARM is for parallelizing the initial sync collection cloning process. Since one of its first uses will be for initial sync collection cloning, it may be good to add and instantiate an ARM in the CollectionCloner that is unused to begin with, as a way to verify that is usable on a mongod.