mongoc_cleanup man page
mongoc_cleanup — mongoc_cleanup()
void mongoc_cleanup (void);
Initialize the MongoDB C Driver by calling mongoc_init exactly once at the beginning of your program. It is responsible for initializing global state such as process counters, SSL, and threading primitives.
Call mongoc_cleanup exactly once at the end of your program to release all memory and other resources allocated by the driver. You must not call any other MongoDB C Driver functions after mongoc_cleanup. Note that mongoc_init does not reinitialize the driver after mongoc_cleanup.
2017-present, MongoDB, Inc