## What changes were proposed in this pull request?
Listeners added with `sparkSession.streams.addListener(l)` are added to a SparkSession. So events only from queries in the same session as a listener should be posted to the listener. Currently, all the events gets rerouted through the Spark's main listener bus, that is,
- StreamingQuery posts event to StreamingQueryListenerBus. Only the queries associated with the same session as the bus posts events to it.
- StreamingQueryListenerBus posts event to Spark's main LiveListenerBus as a SparkEvent.
- StreamingQueryListenerBus also subscribes to LiveListenerBus events thus getting back the posted event in a different thread.
- The received is posted to the registered listeners.
The problem is that *all StreamingQueryListenerBuses in all sessions* gets the events and posts them to their listeners. This is wrong.
In this PR, I solve it by making StreamingQueryListenerBus track active queries (by their runIds) when a query posts the QueryStarted event to the bus. This allows the rerouted events to be filtered using the tracked queries.
Note that this list needs to be maintained separately
from the `StreamingQueryManager.activeQueries` because a terminated query is cleared from
`StreamingQueryManager.activeQueries` as soon as it is stopped, but the this ListenerBus must
clear a query only after the termination event of that query has been posted lazily, much after the query has been terminated.
Credit goes to zsxwing for coming up with the initial idea.
## How was this patch tested?
Updated test harness code to use the correct session, and added new unit test.
Author: Tathagata Das <tathagata.das1565@gmail.com>
Closes#16186 from tdas/SPARK-18758.
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