How to increase Openfire concurrent connection limit?

I am trying to test how many concurrent user connections Openfire can handle. I have noticed a limit at4000 users. How can I handle 50000 concurrent connections or more on Openfire? What configuration should be done to handle large number of connections.

My Server Config

OS - Ubuntu Server 14.04.1 64 bit
Processor - 3.00 GHz
RAM - 512 MB
Openfire Version - 3.9.3

For testing purpose, I am using a virtual server setup on virtualbox.


I’m testing Openfire 3.9.3 without connection manager and with no SSL either (yet). The server is a virtual machine setup on Virtualbox having 3.00GHz processor and 512MB RAM. It is a standard Openfire install with MySQL database connection with 100 maximum connections.

When testing with a load testing script from [Please note I have not setup a cluster] the number of user connection increase steadily till 4000 concurrent user connections. Once 4000 users are connected, all connections begin to drop until all connections are lost and I get an error as follows: Too many open files
at OpenfireClusterStressTest.testMultipleLogin(
at OpenfireClusterStressTest.main(


Cannot handle more than 4000 concurrent user connections. How to increase this limit? What openfire configuration is required to achieve the same?

Posted on answered on stackoverflow: java - How to increase Openfire concurrent connection limit? - Stack Overflow

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