Dbms-alerts

Question

I regeisted an alert using the following syntax in oracle
DECLARE
msg VARCHAR2 (10) := NULL;
status VARCHAR2 (10) := NULL;
BEGIN
DBMS_ALERT.REGISTER('ALERT1234');
LOOP
EXIT WHEN (msg IS NOT NULL);
DBMS_ALERT.waitone ('ALERT1234', msg, status, 10);
END LOOP;
END;
and in another session I am execution ithe below code .
BEGIN
DBMS_ALERT.signal ('ALERT1234', 'hai');
END;
But both sessions are in blocked state .
Can you please let me know how to solve this contention

Answer 1

BEGIN
DBMS_ALERT.signal ('ALERT1234', 'hai');
END;You need to issue commit
BEGIN
    DBMS_ALERT.signal ('ALERT1234', 'hai');
    COMMIT;
END;The document is very clear on that
<pre>
SIGNAL Procedure
This procedure signals an alert. The effect of the SIGNAL call only occurs when
the transaction in which it is made commits. If the transaction rolls back, SIGNAL has no effect.
All sessions that have registered interest in this alert are notified. If the interested
sessions are currently waiting, they are awakened. If the interested sessions are not currently waiting,
they are notified the next time they do a wait call.
Multiple sessions can concurrently perform signals on the same alert. Each session, as it signals the alert,
blocks all other concurrent sessions until it commits. This has the effect of serializing the transactions.
</pre>