DEQUEUE with FOREVER wait time hangs Oracle when there is no entry to be dequeued

Question

I am using a multiconsumer queue and whenever I try to get the next message from the queue with the FOREVER wait time or a wait time greater than 0 and there is not entry in the queue to be dequeued, Oracle seems to hang for a couple of seconds. This time can go from 2 seconds and more than 30 seconds.
During that hang time, I cannot even create a new connection to Oracle, run a query in another session. Everything seems to be hanging. At the same time the machine is mostly idle during that time.
This hang time comes and goes until a message is available to be dequeued or the dequeue call returns when its wait time has elapsed.
Here is the code I use to dequeue the next message with wait time FOREVER from the default.
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DECLARE
msg_queue_msgid msg_queue_tab.msgid%TYPE;
q_opts DBMS_AQ.dequeue_options_t;
msg_opts DBMS_AQ.message_properties_t;
data msg_queue_t;
BEGIN
q_opts.consumer_name := 'ROUTER';
DBMS_AQ.DEQUEUE (queue_name => 'msg_queue',
dequeue_options => q_opts, message_properties => msg_opts,
payload => data,
msgid => msg_queue_msgid);
END;
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Is this related to Oracle configuration or anything special has to be done to use AQ?
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Answer 1

In which mode your database server is running? Probably if its in dedicated mode it will hang u can check it by changing the database mode.
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