503 Spool Over Quota. Queue or Topic endpoint limit exceeded

barisbt
barisbt Member Posts: 9 ✭✭
in PubSub+ Event Broker #1

Hi Community,

I have q1 and q2 which subscribed to topic t/test/baris

When I publish a message to the topic t/test/baris
if q1 quota is exceeded (even if q2 can receive messages in terms of space), the message is rejected by the broker with the below message and none of the queues receive the message as a result.

I understand that this is by design but what is the reasoning for the broker to reject it as a whole?(all or nothing) or is there a way to allow the "other-no problem queues" to receive the messages without any problem?

Thanks

<solace-error-response>
<code>503</code>
<reason>
<![CDATA[Spool Over Quota. Queue or Topic endpoint limit exceeded]]>
</reason>
<detail>
<![CDATA[
Topic "t/test/baris";
SMF AD control client ack response error
]]>
</detail>
<internal-use>2:14136</internal-use>
</solace-error-response>

Best Answers

  • nicholasdgoodman
    nicholasdgoodman Member, Employee Posts: 43 Solace Employee
    #2 Answer ✓

    Yes - by default when any subscription-matching queue is full, the entire message is rejected back to the sender and the message is not enqueued at all.

    This behavior can be changed on a per-queue basis, specifically via the Queue Settings > Advanced Settings > Congestion Control > Reject Messages to Sender on Discard dropdown, which has three options: When Queue Enabled (default), Always, and Never.

    To allow the broker and other queues to still receive a message when a particular queue is full, you can change this setting to Never.

    Screenshot 2024-09-05 092712.png

  • barisbt
    barisbt Member Posts: 9 ✭✭
    #3 Answer ✓

    It looks like my options are different for congestion control. (attached file)

    It worked with "silent" option selected. Thank you for the help / answer Nicholas.


    BTW I am using using Event Broker Service Version10.8.1.140-5) it is in fact SAP Advanced Event Mesh.

    Queue-Cong.jpg

Answers

  • nicholasdgoodman
    nicholasdgoodman Member, Employee Posts: 43 Solace Employee
    #4 Answer ✓

    Yes - by default when any subscription-matching queue is full, the entire message is rejected back to the sender and the message is not enqueued at all.

    This behavior can be changed on a per-queue basis, specifically via the Queue Settings > Advanced Settings > Congestion Control > Reject Messages to Sender on Discard dropdown, which has three options: When Queue Enabled (default), Always, and Never.

    To allow the broker and other queues to still receive a message when a particular queue is full, you can change this setting to Never.

    Screenshot 2024-09-05 092712.png

  • barisbt
    barisbt Member Posts: 9 ✭✭
    #5 Answer ✓

    It looks like my options are different for congestion control. (attached file)

    It worked with "silent" option selected. Thank you for the help / answer Nicholas.


    BTW I am using using Event Broker Service Version10.8.1.140-5) it is in fact SAP Advanced Event Mesh.

    Queue-Cong.jpg

  • Aaron
    Aaron Member, Administrator, Moderator, Employee Posts: 634 admin
    edited September 6 #6

    Interesting… I didn't know that even some of the terminology in Manager is remapped when deployed as SAP AEM. EDIT: it looks like the term "Silent" was added to more recent Solace brokers as well… I guess Nick and I are a bit out of date!

    Yeah, "Silent" will make your q1 queue into essentially a "best effort" queue, and that it will be fully Guaranteed with ACKs and everything until it is full, and then it'll just lose new messages while its spool is over quota.

  • barisbt
    barisbt Member Posts: 9 ✭✭
    #7

    Thanks for the explanation Aaron. Yes it should be broker version that makes this difference.

    Baris

  • Gopal4506
    Gopal4506 Member Posts: 2 ✭
    #8

    I have something similar options as @barisbt. But the silent option is not working for me. Am still getting the spool over quota error as some other queue is consuming to the same subscription.

    image.png

    Any help would be grateful.


    Thanks
    Gopal

  • Aaron
    Aaron Member, Administrator, Moderator, Employee Posts: 634 admin
    #9

    Hi @Gopal4506, welcome to the Community..! Yeah, if some other queue is full, and not configured to discard silently, then the publisher will get a NACk.

    Just to be clear to all reading this thread: 99.99% of the time, you do NOT want the broker throwing away your Guaranteed messages. That's essentially what can happen if you configure your queue to be Silent for the "Reject Messages to Sender on Discard"… even though my queue is full, doesn't matter, don't tell the publisher.

    Why is your queue full?? This should only happen if your consumers are crashed out for a LONG time.

    If this is development, why not configure the queue's Max TTL to automatically clean it out after a day or a week or whatever?

  • barisbt
    barisbt Member Posts: 9 ✭✭
    #10

    In addition to what @Aaron mentioned, @Gopal4506 What was the expected behaviour from your side when you select "silent"? Is it possible that you have other queues that is also not "silent" with the same subscription, as the broker works as expected for me.

    Baris

  • Gopal4506
    Gopal4506 Member Posts: 2 ✭
    #11

    Sorry to get back here after many days. and many thanks for your replies
    @Aaron I have configured only my queue to "silent", so as @barisbt mentioned all the queues should be set to Silent

    So now I get it that- all the queues which has matching subscription must be set to "silent", so that the publisher will get a successfull ACK.
    My follow query would be: Instead of setting all the queues to "Silent", Only the queue which got consumed fully set to "Silent"- Will this work?

    also @Aaron, TTL works in my case, but I just wanted to test this setting of "Reject Messages to Sender on Discard".

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