Version of Mongodb driver:
[dependencies.mongodb]
version = "1.1.1"
default-features = false
features = ["async-std-runtime"]
Version of Mongodb:
docker, mongo:4.2-bionic
Version of rust:
x86_64 1.49.0-nightly (91a79fb29 2020-10-07)
The following code first inserting 30000 documents using insert_many, then drop the collection and the client. After dropped everything, the memory usage is over 200MB.