Message queuing using --disable-clean-session option not working in mosquitto_sub

[fuxoft]

I have created this minimal Linux script to show the problem:

I am attempting to queue 10 messages and then receive them separately, one after another, using command line tools. The first message is received and displayed but the remaining 9 are never displayed.

(Mosquitto server runs with default configuration)

#!/usr/bin/bash
# Clear sessin for client "receiver" (ends with timeout as expected):
mosquitto_sub -V 5 -i receiver --nodelay -q 2 -W 1 -t "spam"
# Tell the server to store "receiver"'s session (ends with timeout as expected):
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -W 1 -t "spam"
# Queuing 10 messages:
mosquitto_pub -V 5 -i spammer --nodelay -q 2 -t "spam" -m "A"
mosquitto_pub -V 5 -i spammer --nodelay -q 2 -t "spam" -m "B"
mosquitto_pub -V 5 -i spammer --nodelay -q 2 -t "spam" -m "C"
mosquitto_pub -V 5 -i spammer --nodelay -q 2 -t "spam" -m "D"
mosquitto_pub -V 5 -i spammer --nodelay -q 2 -t "spam" -m "E"
mosquitto_pub -V 5 -i spammer --nodelay -q 2 -t "spam" -m "F"
mosquitto_pub -V 5 -i spammer --nodelay -q 2 -t "spam" -m "G"
mosquitto_pub -V 5 -i spammer --nodelay -q 2 -t "spam" -m "H"
mosquitto_pub -V 5 -i spammer --nodelay -q 2 -t "spam" -m "I"
mosquitto_pub -V 5 -i spammer --nodelay -q 2 -t "spam" -m "J"
# Expecting to receive 10 messages one after another
# but receiving only first message ("A") plus 9 timeouts:
echo "Attempting to receive A"
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -d -C 1 -W 1 -t "spam" -v
echo "Attempting to receive B"
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -d -C 1 -W 1 -t "spam" -v
echo "Attempting to receive C"
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -d -C 1 -W 1 -t "spam" -v
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -C 1 -W 1 -t "spam" -v
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -C 1 -W 1 -t "spam" -v
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -C 1 -W 1 -t "spam" -v
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -C 1 -W 1 -t "spam" -v
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -C 1 -W 1 -t "spam" -v
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -C 1 -W 1 -t "spam" -v
mosquitto_sub -V 5 -c -i receiver --nodelay -q 2 -C 1 -W 1 -t "spam" -v

Complete script output follows. Look especially at the debug output after "Attempting to receive B". 9 messages seem to be received all at once and never printed:

Timed out
Timed out
Attempting to receive A
Client receiver sending CONNECT
Client receiver received CONNACK (0)
Client receiver sending SUBSCRIBE (Mid: 1, Topic: spam, QoS: 2, Options: 0x00)
Client receiver received PUBLISH (d0, q2, r0, m1, 'spam', ... (1 bytes))
Client receiver sending PUBREC (m1, rc0)
Client receiver received PUBLISH (d0, q2, r0, m2, 'spam', ... (1 bytes))
Client receiver sending PUBREC (m2, rc0)
Client receiver received PUBLISH (d0, q2, r0, m3, 'spam', ... (1 bytes))
Client receiver sending PUBREC (m3, rc0)
Client receiver received PUBLISH (d0, q2, r0, m4, 'spam', ... (1 bytes))
Client receiver sending PUBREC (m4, rc0)
Client receiver received PUBLISH (d0, q2, r0, m5, 'spam', ... (1 bytes))
Client receiver sending PUBREC (m5, rc0)
Client receiver received PUBLISH (d0, q2, r0, m6, 'spam', ... (1 bytes))
Client receiver sending PUBREC (m6, rc0)
Client receiver received PUBLISH (d0, q2, r0, m7, 'spam', ... (1 bytes))
Client receiver sending PUBREC (m7, rc0)
Client receiver received PUBLISH (d0, q2, r0, m8, 'spam', ... (1 bytes))
Client receiver sending PUBREC (m8, rc0)
Client receiver received PUBLISH (d0, q2, r0, m9, 'spam', ... (1 bytes))
Client receiver sending PUBREC (m9, rc0)
Client receiver received PUBLISH (d0, q2, r0, m10, 'spam', ... (1 bytes))
Client receiver sending PUBREC (m10, rc0)
Client receiver received SUBACK
Subscribed (mid: 1): 2
Client receiver received PUBREL (Mid: 1)
Client receiver sending PUBCOMP (m1)
spam A
Client receiver sending DISCONNECT
Attempting to receive B
Client receiver sending CONNECT
Client receiver received CONNACK (0)
Client receiver sending SUBSCRIBE (Mid: 1, Topic: spam, QoS: 2, Options: 0x00)
Client receiver received PUBREL (Mid: 2)
Client receiver sending PUBCOMP (m2)
Client receiver received PUBREL (Mid: 3)
Client receiver sending PUBCOMP (m3)
Client receiver received PUBREL (Mid: 4)
Client receiver sending PUBCOMP (m4)
Client receiver received PUBREL (Mid: 5)
Client receiver sending PUBCOMP (m5)
Client receiver received PUBREL (Mid: 6)
Client receiver sending PUBCOMP (m6)
Client receiver received PUBREL (Mid: 7)
Client receiver sending PUBCOMP (m7)
Client receiver received PUBREL (Mid: 8)
Client receiver sending PUBCOMP (m8)
Client receiver received PUBREL (Mid: 9)
Client receiver sending PUBCOMP (m9)
Client receiver received PUBREL (Mid: 10)
Client receiver sending PUBCOMP (m10)
Client receiver received SUBACK
Subscribed (mid: 1): 2
Client receiver sending DISCONNECT
Timed out
Attempting to receive C
Client receiver sending CONNECT
Client receiver received CONNACK (0)
Client receiver sending SUBSCRIBE (Mid: 1, Topic: spam, QoS: 2, Options: 0x00)
Client receiver received SUBACK
Subscribed (mid: 1): 2
Client receiver sending DISCONNECT
Timed out
Timed out
Timed out
Timed out
Timed out
Timed out
Timed out
Timed out

[ralight]

Thanks, that's a handy script. This is straightforward to fix for MQTT v5 in principle using the receive maximum property. It's less easy for MQTT v3*. I'd have a fix for you already, but it has highlighted something else I need to fix first.

[fuxoft]

Oh, so I am not doing anything wrong and it's indeed a bug? That's a relief, I was going crazy over it for 2 hours, thanks.