Per API docs on StreamingQuery.stop(),
https://spark.apache.org/docs/latest/api/scala/org/apache/spark/sql/streaming/StreamingQuery.html
It says, this stops the execution of this query if it is running and waits until the termination of the query execution threads or until a timeout is hit.
This doesn't mean it waits for micro-batch completion. It will interrupt all active threads but wait until the termination or completion if it couldn't interrupt the current "thread" running. Sometimes we use uninterruptible threads, e.g. with Kafka - because interrupting Kafka threads bricks the cluster. All other threads will be interrupted.
