Difference between new listener vs new instance

[sridhar krishnamurthy]

I run MQTT on windows 2012 R2 server and I have a need for it to support over 100K connections.  I run a single instance mqtt as a broker service on the default port 1883.

1. From my testing I have seen that the maximum number of client connections it can support is about 55K from client A.  

2. I added an additional mqtt listener on port 1884 and started a new client B.  

As soon as I ran B, the number of connections from A dropped and eventually they both stabilized at around 25K connections from each of A and B.

3. I then started a new instance of mqtt on the server from command line on port 1885

I configured client A and B to make 50K tcp connections each and noticed that they both reached close to 50K each.

What is the difference between running mqtt with multiple listeners vs running they as separate instance.  

Do each instance of mqtt has a limitation of about 55K connections?

[Nick O'Leary]

Hi,

This mailing list is about the protocol rather than any specific implementation. You don't say which implementation you are using so it's hard to answer your questions or direct you to the appropriate place.

Nick

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[sridhar krishnamurthy]

Thanks for your response Nick.  Our implementation has each of our client making a persistent connection to mqtt server so they may be reached any time as and when required.  MQTT server lies between the clients and the application server and is used to request the client to contact the server.  But my test is to simulate that scenario with 2 simulators.  Each simulator simulates 50K client connections.  Please let me know if that was the detail you were looking for.

[Nick O'Leary]

Hi,

no, that doesn't answer the question. Which MQTT implementation are you using? We cannot answer questions about a specific implementation of the protocol if you don't tell us which implementation you are using.

Nick

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[ran...@bevywise.com]

I see this more to be a windows open files limit than the program itself.  There will be limits for the number of open files per program which defines the number of TCP connections that can be opened. Do check and increase it. 

Sorry that I am not able to locate a right reference guide for increasing the values in windows. 

Cheers, 

Ranjith 

CEO, 

Bevywise Networks.