Benchmark of mosquitto clustering?

Question

I'm trying to build an mosquitto clustering, because mosquitto is single thread and seems cannot handle lots of qos 2 messages.

MQTT server comparison: Benchmark of MQTT Servers

I found mosquitto can use bridge way to build cluster (Cluster forming with Mosquitto broker), but I'm wondering if mosquitto subscribe all message from all other server will cause high overhead for internal message sending.

For example, if I have 10 mosquitto brokers, each of them serve 1,000 messages, originally it's total 10,000 messages. But messages will shared between brokers, so each message will send to another 9 brokers, that's a total 1,000 x 9 x 10 = 90,000 message for internal usage.

Is there some benchmark for mosquitto clustering? Or what's the general solution for sending lots of qos 2 messages?

Thanks

Answer 1

We used to setup a MQTT service platform which use Mosquitto as the broker, with 8 brokers bridged together, about 20k clients subscribed with 20k topics, qos=0, avg pubs 1k messages/sec with 100-2k bytes, the bridge subscribe and publish all the topics, and bring a huge forward latency, sometimes more then 2 mins. So now we simply broadcast all the pubs to each of the broker, this does work. But bridge is something else with cluster, which means it does not like a logic MQTT broker that support cluster session, load balance, single point of failure,.. so I have implemented a autonomous Mosquitto cluster, and did some performance test by Tsung, generally speaking, with a scenario that 30k subscriber/2.5k pubs/sec, payload length=744bytes, qos=1, average request response is a bit high then bridge(5.1ms vs 2.32ms), but no message lost and the load did balanced. you can find the detailed test report under mosquitt-cluster-bridge-benchmark.