Rabbitmq queue mirroring policy don't work when TTL policy is added to the cluster

[qrshat]

0

On a five nodes rabbitmq cluster,I created two policies. One is for queue replication and the other is for TTL poliecs.

When I create a queue replication policy with the below commands, It works successfully, without any error.

rabbitmqctl set_policy ha-three .replica. '{"ha-mode":"exactly","ha-params":2,"ha-sync-mode":"automatic"}'

After creating the queue replication policy, I added a TTL policy with the below command. But when I add the TTL policy, the queue replication policy lost its functionality and don't work. When I remove the TTL leave policy, the replication policy starts to work properly again.

rabbitmqctl set_policy TTL ".*" '{"message-ttl":3600000}' --apply-to queues

I don't understand why TTL policy affects the queue replication policy. Did I miss something? I want two policies are working on the same cluster without effecting each other.

[Luke Bakken]

Hello,

Only one policy at a time can be active for a queue. When you add your second policy, it matches all queues and probably is the one being applied.

If you want have your ha-three policy take precedence, give it a higher priority via the --priority argument - 

https://www.rabbitmq.com/rabbitmqctl.8.html#set_policy

If you want to have both TTL and ha-three apply to a queue, you'll have to create a new policy that combines the two and assign it the correct regex and priority to be applied.

Thanks,

Luke

[qrshat]

Thanks Luker, I appreciate your answer.  I've created a combined policy and it works perfectly. 

[qrshat]

Hi All,

When I set the below combined policy, It works fine.

# rabbitmqctl set_policy ha-three-TTL test  '{"ha-mode":"exactly","ha-params":3,"ha-sync-mode":"automatic","message-ttl":3600000}'

When I set the below policies, they also work fine.

# rabbitmqctl set_policy test_TTL .*test.* '{"message-ttl":3600000}' --apply-to queues --priority 44
 # rabbitmqctl set_policy test_TTL_SMS .*test.Sms.* '{"message-ttl":18000000}' --apply-to queues --priority 51
 # rabbitmqctl set_policy test_TTL_Mail .*test.Mail.* '{"message-ttl":18000000}' --apply-to queues --priority 52

 # rabbitmqctl set_policy test_TTL_ServiceLog .*test.ServiceLog.* '{"message-ttl":86400000}' --apply-to queues --priority 58 

But when I set the below policies, they don't work as I expected. TTL policies didn't clear the queue for the test queue and test Sms queue and so. 

 # rabbitmqctl set_policy ha-three-test_TTL   .*test.*  '{"ha-mode":"exactly","ha-params":3,"ha-sync-mode":"automatic","message-ttl":3600000}' --apply-to queues --priority 44

 # rabbitmqctl set_policy ha-three-test_TTL_SMS  .*test.Sms.*   '{"ha-mode":"exactly","ha-params":3,"ha-sync-mode":"automatic","message-ttl":18000000}' --apply-to queues --priority 52
  # rabbitmqctl set_policy ha-three-test_TTL_Mail  .*test.Mail.*   '{"ha-mode":"exactly","ha-params":3,"ha-sync-mode":"automatic","message-ttl":18000000}' --apply-to queues --priority 52
  # rabbitmqctl set_policy ha-three-test_TTL_ServiceLog  .*test.ServiceLog.*   '{"ha-mode":"exactly","ha-params":3,"ha-sync-mode":"automatic","message-ttl":86400000}' --apply-to queues --priority 58
 

I don't understand the reason of why the policies don't work as my expectations. Is there  anyone who know how I should set the policies. I just want queue replication policies and TTL policies to work together according to the priority I set.

I googled a lot, but didn't find any solid solution to that.

Thanks in advance

[Luke Bakken]

You should run rabbitmqctl report and be 100% sure the policy you expect is being applied to the queue you expect.

[kjnilsson]

Not to do with policies but just to make sure you are aware that HA classic queues are deprecated in favour of quorum queues and if this is a new system you are configuring I would recommend moving to quorum queues instead (also you don't need an HA policy for them as they are inherently HA)

https://blog.rabbitmq.com/posts/2021/08/4.0-deprecation-announcements/

[qrshat]

Very thanks Kjnilsson.Luker.  I start to use quorum queues instead of classic. All the policies are started to work properly.  But,  after using quorum queues,  I observed that producer services feed the queues slower than classic queues. Is that normal or do I miss any configuration that results this performance issue?

[kjnilsson]

As a general rule QQs tend to have better throughput than _mirrored_ classic queues but higher latency than non mirrored classic queues (v2). So if you wait for publisher confirms after each message send operation it may seem slower.

[kjnilsson]

Also if you use a new channel for each publish it will definitely be slower. QQs are optimised for long running connections / channels.