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javalinuxrmi

How Do I Change The RMI Listen Backlog Size?

I am having network issues with my Java (7) application on linux where packets are occasionally delayed.

The sysadmins have said that the listen backlog set is too low and thus is not accepting connections fast enough.

ss -lt
State      Recv-Q Send-Q    Local Address:Port    Peer Address:Port
LISTEN     0      50        *:1099                *:*

The default on this system is 128

sysctl -a 2>/dev/null|grep net.core.somaxconn
net.core.somaxconn = 128

Is 50 the default for RMI connections in JDK7?

How do I increase it to make it use the system default?

Solution

  • It looks like 50 is the default value in the JDK.

    sun.rmi.transport.tcp.TCPEndpoint calls RMIServerSocketFactory.createServerSocket(this.listenPort); The implementations of RMIServerSocketFactory e.g. RMIDirectSocketFactory do new ServerSocket(int);

    As we can see from the ServerSocket javadocs: https://docs.oracle.com/javase/7/docs/api/java/net/ServerSocket.html#ServerSocket(int)

    The maximum queue length for incoming connection indications (a request to connect) is set to 50

    Therefore, one way to increase the value is to create your own implementation of RMIServerSocketFactory and call a different ServerSocket constructor that allows you to set your own backlog value.