qos 0 messages is not being sent to connected subscribers

[quackgizmo]

A client subscribes to a topic, another client publishes two messages to that topic, one with qos 0 and one with qos 1, only the message with qos 1 is received by the first client.

It fails with the 2.0.8 version, but it used to work with the 1.6.12 version.

This is the mosquitto log.

1615196145: mosquitto version 2.0.8 starting
1615196145: Config loaded from /mosquitto/config/mosquitto.conf.  
1615196145: Opening ipv4 listen socket on port 1883.  
1615196145: Opening ipv6 listen socket on port 1883.
1615196145: mosquitto version 2.0.8 running
1615196205: Saving in-memory database to /mosquitto/data//mosquitto.db.
1615196266: Saving in-memory database to /mosquitto/data//mosquitto.db.
1615196274: New connection from 127.0.0.1:59246 on port 1883.
1615196274: New client connected from 127.0.0.1:59246 as subscriber (p2, c1, k60).
1615196274: No will message specified.
1615196274: Sending CONNACK to subscriber (0, 0)
1615196274: Received SUBSCRIBE from subscriber
1615196274: 	test/# (QoS 1)
1615196274: subscriber 1 test/#
1615196274: Sending SUBACK to subscriber
1615196309: New connection from 127.0.0.1:59248 on port 1883.
1615196309: New client connected from 127.0.0.1:59248 as publisher (p2, c1, k60).
1615196309: No will message specified.
1615196309: Sending CONNACK to publisher (0, 0)
1615196309: Received PUBLISH from publisher (d0, q1, r0, m1, 'test/qos1', ... (4 bytes))
1615196309: Sending PUBLISH to subscriber (d0, q1, r0, m1, 'test/qos1', ... (4 bytes))
1615196309: Sending PUBACK to publisher (m1, rc0)
1615196309: Received DISCONNECT from publisher
1615196309: Client publisher disconnected.
1615196309: Received PUBACK from subscriber (Mid: 1, RC:0)
1615196325: New connection from 127.0.0.1:59250 on port 1883.
1615196325: New client connected from 127.0.0.1:59250 as publisher (p2, c1, k60).
1615196325: No will message specified.
1615196325: Sending CONNACK to publisher (0, 0)
1615196325: Received PUBLISH from publisher (d0, q0, r0, m0, 'test/qos0', ... (4 bytes))
1615196325: Outgoing messages are being dropped for client subscriber.
1615196325: Received DISCONNECT from publisher
1615196325: Client publisher disconnected.
1615196328: Saving in-memory database to /mosquitto/data//mosquitto.db.
1615196369: Received PINGREQ from subscriber
1615196369: Sending PINGRESP to subscriber

The queues are not full, these two messages are the only ones being sent. So the Outgoing messages are being dropped for client subscriber seems a little strange.

This is the mosquitto configuration.

persistence true
persistence_location /mosquitto/data/
autosave_interval 60
max_inflight_messages 1000
max_inflight_bytes 134217728
max_queued_messages 100000
max_queued_bytes 268435456
allow_anonymous true
log_dest stdout
log_type all
connection_messages true
listener 1883

It can easily be reproduced by starting a subscriber with mosquitto_sub -h localhost -i subscriber -t test/# -q 1 -d -v. And then sending the two messages with mosquitto_pub -h localhost -i publisher -t test/qos1 -q 1 -m "test" -d and mosquitto_pub -h localhost -i publisher -t test/qos0 -q 0 -m "test" -d.

[ralight]

Thanks for the nice description. This is a regression on the max_*_bytes options for QoS 0 messages only. I've just pushed a fix for it which will be part of 2.0.9.