Retain functionality works inconsistently

[saraheem]

Version: 3.3.3
Deployment Config: Windows 11, OpenJDK 21.0.5, Standalone mode, Default configuration
Tools: Using Mqtt-Stresser for pub/sub

A Steps:

1. Connect 50 Clients, each client publishes 1 messages on 1 Topic (test\client-1, test\client-2, test-client-3....) with QOS 1, Retain true.

Behavior:
No message being retained.

B Steps:

1. Delete Data\retain_data folder
2. Start Stand alone server
3. Connect 50 Clients, each client publishes 1 messages on 1 Topic (test\client-1, test\client-2, test-client-3....) with QOS 1, Retain true.

Behavior:
Only 10 topics are retained and the rest do not get retained

C Steps:

1. Connect 50 Clients, each client publishes 1 messages on 1 Topic (test\client-1, test\client-2, test-client-3....) with QOS 0, Retain true.

Behavior:
It seems that only 10 messages every get retained, is this a configuration flag

[Gujiawei-Edinburgh]

"It seems that only 10 messages every get retained, is this a configuration flag"
I think there is no such a limit for the retain storage. How do you find that the message is not retained, e.g by subscribing the topic? I think may be BifroMQ can add a listRetainMessage in api server.

[saraheem]

@Gujiawei-Edinburgh, in the info log there was the following line: RetainMessageMatchLimit=10, is it possible that this has to do with the reported behavior? seems that this configuration sets the match limit for a retain message topic subscription match? where can we change this config from?

How do you find that the message is not retained, e.g by subscribing the topic? No, I am doing a wildcard subscription and i've figured that is the real issue. Bifromq will limit the retained topics matched if its a wildcard subscription based on the RetainMessageLimit config flag.

[Gujiawei-Edinburgh]

@saraheem If your subscribed topic, i.e. topic filter, has wildcard, e.g. * or #, it will match multiple topics. If so, during matching process, if the number of matched topics exceeds the limit which is 10 by default, you cannot get all the retained messages. You can write your own setting provider to override the default settings.