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Latency of Mqtt Messages [message #1796789]

Thu, 18 October 2018 23:16

Talha Ghaffar

Messages: 6
Registered: February 2017

Junior Member

Hi,

I want to measure the time that a published message spends in the Mosquitto broker. My goal is to determine the latency breakdown of MQTT messages.
1. from publisher to reception by the broker
2. time spent in the broker
3. from broker_publish to reception by the subscriber.

My setup, for now, is a multiple publishers publishing to broker but one subscriber. I am using clean session & QoS = 1.

I am measuring total latency by adding a timestamp in payload @ publisher and taking the diff at the subscriber. From pub-to-broker, I am measuring it by taking /2 of the diff between timestamp @ publish time and timestamp @ reception of PUBACK [(T2-T1)/2].

I am not sure how other two components could be measured.

I haven't come across any stats/debug info that Mosquitto might provide regarding the time spent by a message in the broker. Does/Can mosquitto provide this data?

Thanks!

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Re: Latency of Mqtt Messages [message #1836410 is a reply to message #1796789]

Sat, 02 January 2021 15:24

Gambit Support

Messages: 46
Registered: March 2019

Member

Check our blog post for performance testing issues:

https://gambitcomm.blogspot.com/2018/08/video-monitor-end-to-end-latency-of.html

"There are many variables that could impact the latency: the distance
between sensors, brokers and applications, the message profile, that
is the average size of the payload and frequency of the messages, the
QOS of the messages, the topic hierarchy being published to, the number
of subscriber clients and their performance, the retention policy for
messages, and many more. Only your particular requirements would tell
whether the performance is acceptable for you."

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