Hybrid queue?

Question

1. I had posted a question on how to do the callback with a sp to auto-dequeue. We have it working with the OEM scheduler and set the deque option's WAIT parm to FOREVER. This leaves an event handler/listener job running out there waiting/listening for more messages to process and call our dequeue job(which parses a clob out to the db). So that works nice but it's single threaded. Is there any parameters to set somewhere to tell it to spawn another thread to process multiple messages at the same time?
2. We were also able to create a 2nd type of queue. This uses the demo_queue example out there on the web to create a true queue. IE: it waits and processes whatever is in the queue automatically every 5 seconds. The interesting thing about this version of a queue is that it seems to spawn 10 threads to handle the processing load of the messages that piled up in this bucket since the last run 5 seconds ago.
What we would like is to combine the best of both worlds: We want a process to wait forever listening for more messages being enqueued and automatically fire off the dequeue like in #1 above but if say 1000 customers enqueue something within a few seconds of each other, have oracle auto-magically spawn say 100 threads so none of them are noticing any wait time. A hybrid if you will.
Is this possible and if so, how?
Thanks in advance for your replies.
Dave

Answer 1

Here's what we are trying to do but the deque procedure parms are not keeping it pinned up in memory "listening"(if that's accurate). It works and opens up 10 threads when we run the TESTER(see section below) but there's a wait delay before whatever it is POLLS the queue to see if it's supposed to fire itself off. The paramaters that we have working in a different version work and keep it up in memory but then its only single threaded....does this make our issue clear to understand? r_dequeue_options.wait := dbms_aq.forever;
VERSION 1 - Oracle polls queue every few seconds then processes en mass via multi-threading:
create or replace type demo_queue_payload_type as object(message varchar2(4000));
create table demo_queue_message_table(message varchar2(4000));
exec dbms_aqadm.create_queue_table(queue_table => 'demo_queue_table', queue_payload_type => 'demo_queue_payload_type', multiple_consumers => true);
exec dbms_aqadm.create_queue(queue_name => 'demo_queue', queue_table => 'demo_queue_table');
exec dbms_aqadm.start_queue (queue_name => 'demo_queue');
exec dbms_aqadm.add_subscriber(queue_name => 'demo_queue', subscriber => sys.aq$_agent('demo_queue_subscriber', null, null));
exec dbms_aq.register(sys.aq$_reg_info_list(sys.aq$_reg_info('demo_queue:demo_queue_subscriber', dbms_aq.namespace_aq, 'plsql://demo_queue_callback_procedure', hextoraw('ff'))), 1);
create or replace procedure demo_queue_callback_procedure
context raw,
reginfo sys.aq$_reg_info,
descr sys.aq$_descriptor,
payload raw,
payloadl number
) as
r_dequeue_options dbms_aq.dequeue_options_t;
r_message_properties dbms_aq.message_properties_t;
v_message_handle raw(16);
o_payload demo_queue_payload_type;
begin
r_dequeue_options.msgid := descr.msg_id;
r_dequeue_options.consumer_name := descr.consumer_name;
r_message_properties.delay := dbms_aq.no_delay;
r_dequeue_options.wait := dbms_aq.forever;
r_dequeue_options.visibility := dbms_aq.immediate;
dbms_aq.dequeue
queue_name => descr.queue_name,
dequeue_options => r_dequeue_options,
message_properties => r_message_properties,
payload => o_payload,
msgid => v_message_handle
insert into demo_queue_message_table (message) values (to_number(to_char(systimestamp,'ss.ff3')) - to_number(o_payload.message));
commit;
end;
TESTER - Run this anonymous block to test the queue created above then notice how all of their DEQUEUED times are delayed several seconds - Due to polling and not staying up in memeory as a listener:
declare
r_enqueue_options dbms_aq.enqueue_options_t;
r_message_properties dbms_aq.message_properties_t;
v_message_handle raw(16);
o_payload demo_queue_payload_type;
counter number := 1;
begin
while counter <= 10000 loop
o_payload := demo_queue_payload_type(to_char(systimestamp, 'ss.ff3'));
dbms_aq.enqueue
queue_name => 'demo_queue',
enqueue_options => r_enqueue_options,
message_properties => r_message_properties,
payload => o_payload,
msgid => v_message_handle
commit;
counter := counter + 1;
end loop;
end;
Does that make sense?
Thanks,
Dave
Message was edited by:
user613052