[CT-1440] [Bug] Connection reused event is not shown

[JCZuurmond]

Is this a new bug in dbt-core?

• I believe this is a new bug in dbt-core
• I have searched the existing issues, and I could not find an existing issue for this bug

Current Behavior

The connection reused event does not show in the logs: Re-using an available connection from the pool (formerly {self.conn_name})

I think this is because the connection reused event is never fired.

I am not completely sure if I am reading the code below correctly, but I think the ConnectionReused is misplaced and maybe never reached:

        conn = self.get_if_exists()
        if conn is None:
            conn = Connection(
                type=Identifier(self.TYPE),
                name=None,
                state=ConnectionState.INIT,
                transaction_open=False,
                handle=None,
                credentials=self.profile.credentials,
            )
            self.set_thread_connection(conn)

        if conn.name == conn_name and conn.state == "open":
            return conn

        fire_event(NewConnection(conn_name=conn_name, conn_type=self.TYPE))

        if conn.state == "open":
            fire_event(ConnectionReused(conn_name=conn_name))
        else:
            conn.handle = LazyHandle(self.open)

        conn.name = conn_name
        return conn

I read the following

1. The code fetches an existing connection
2. If no connection exists, it creates a new one and adds the connection to be used later
3. If the connection has the same name and is open, the connection is returned immediately
4. If not, a new connection event is sent
5. Then if the connection is open, a connection reused event is sent
6. Else lazy handler is set
7. Connection is returned

I do not understand why the connection reused event might be sent right after the new connection event is sent.

Also, I do not understand when this conn.name == conn_name evaluates to False. When is a different connection name used within the same thread?

Expected Behavior

        conn = self.get_if_exists()
        if conn is None:
            conn = Connection(
                type=Identifier(self.TYPE),
                name=None,
                state=ConnectionState.INIT,
                transaction_open=False,
                handle=None,
                credentials=self.profile.credentials,
            )
            self.set_thread_connection(conn)

        if conn.state == ConnectionState.OPEN.
            fire_event(ConnectionReused(conn_name=conn_name))
        else:
            fire_event(NewConnection(conn_name=conn_name, conn_type=self.TYPE))
            conn.handle = LazyHandle(self.open)
            conn.name = conn_name
        return conn

Steps To Reproduce

NA

Relevant log output

NA

Environment

- OS: NA
- Python: NA
- dbt: v.1.3.0

Which database adapter are you using with dbt?

No response

Additional Context

No response

[lostmygithubaccount]

thanks @JCZuurmond! your read on this makes sense to me

[gshank]

There is a connection per thread. If a connection already exists, it is reused and named with the new connection name (usually the unique_id of the node). I think it will be more clear in the modified ConnectionReused message.