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Is there a limit for max online users in a room?

Igor Khomenko
Added about 4 years ago

Is there a limit for max online users in a room?

Is it possible to have 20K online users for example?

or it just depends on hardware?


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Added by Artur Hefczyc TigaseTeam about 4 years ago

There is not specific limit in software for a number of users in a MUC room. In fact we have run some tests and have one deployment which uses MUC for 20k or more users in a single room. However, you must realize what it really means to have 20k users in a single room. Here is a a few numbers what happens when you have 20k users in a single room:

  1. Every single message or presence change sent to the room generates 20k messages or presences to all occupants

  2. If every person in the room sends only 1 message per minute to the room it means:

    1. 333 messages in total are sent to the room per second
    2. Each of above 333 messages generate 20k messages which gives you over 6.6M messages per second in total
    3. Assuming each message stanza is about 1kB in size, this gives you 7GB/sec if network traffic
    4. It also means every single person in the room receives 333 messages per second in their client - this is not a very useful thing for any human being

While 20k online users is actually a low number of a single Tigase XMPP Server, even on average server class machine, the traffic of 6.6M messages per second is not something that can be handled on a single machine, even very powerful one. Even the low-level network traffic os 7GB/sec is an issue here. So you will need a cluster of Tigase servers to distribute the MUC traffic. There is a specialized ACS component for MUC dedicated to use-cases like this.

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Added by Igor Khomenko about 4 years ago

Thanks Artur,

really great and very useful answer!

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