MQTT error [-12]: No more messages can be buffered

[HaogeZhou]

Hi All,
I write a easy script trying to publish a 1MB txt file to the specific topic that connected with broker.
But I met the error following.

[ WARN] [1696218984.040646955]: Publishing ROS message type information to MQTT topic 'mqtt_client/ros_msg_type/pingpong/ros' failed: MQTT error [-12]: No more messages can be buffered
[ WARN] [1696218984.041366993]: Publishing ROS message type information to MQTT topic 'pingpong/ros' failed: MQTT error [-12]: No more messages can be buffered

How to increase the buffer size?

[bastilam]

Before increasing the buffer size, I would recommend to find out why the buffer is not sufficient. Possibly, you are publishing more data than your system can handle, and increasing the buffer size will only lead to a delay of the same warning, but it will not solve it, because the buffer will be full just a little later.

At what frequency are you publishing the 1 MB data? Maybe you can try to decrease this frequency. If you don't necessarily need to publish 1 MB, but a smaller amount of data would also suffice, you could also try this.