Hello Mosquitto Developers,
I’ve observed a behavior with persistent sessions in Mosquitto and would like to confirm if this is expected.
Setup:
Mosquitto version 2.0.22 with persistence enabled:
persistence true
persistence_location /path/mosq/data/
MQTT v3.1.1 clients using stable client_ids.
Publisher uses QoS 1.
Subscriber (client2) connects with clean_session=false and then disconnects.
Test sequence:
1. Both publisher and subscriber connect. Subscriber uses clean_session=false.
2. Disconnect client2 and keep it offline.
3. Publish some X messages → they queue for client2.
4. Restart the Mosquitto broker (so it reloads its persistent database).
5. Without reconnecting client2, publish some more Y messages.
6. Reconnect client2.
Result:
On reconnect, client2 receives the X messages (published before the broker restart).
It does not receive the Y messages published after the restart while it was still offline.
Question:
Is this the intended behavior?
After a broker restart, must a client reconnect at least once to re-establish its session before the broker will queue new QoS 1 messages for it?
I had assumed that if a session was persisted and restored, the broker would continue to queue new QoS 1 messages for that client even if it hadn’t reconnected yet — but in my test, that did not happen.
Thanks for clarifying how persistent sessions are expected to behave after a restart.
Regards,
Mohd Uvaish
New Delhi, India
