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  1. JDK
  2. JDK-8236187

Add support for per Socket configuration of TCP keepalive

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Details

    • CSR
    • Resolution: Approved
    • P3
    • 8-pool
    • core-libs
    • None
    • source
    • minimal
    •  There is a new API, there are no compatibility issues.
    • Java API

    Description

      Summary

      TCP_KEEPIDLE, TCP_KEEPCOUNT, and TCP_KEEPINTERVAL are non-standard socket options supported on several platforms to provide fine control over the TCP/IP keep alive mechanism. It should be possible to set these socket options via the setOption method defined by java.net.Socket and java.nio.channels.SocketChannel.

      Problem

      When the SO_KEEPALIVE option is enabled, TCP probes a connection that has been idle for some amount of time. The default value for this idle period is 2 hours which is too long for most applications. The TCP_KEEPIDLE, TCP_KEEPCOUNT, TCP_KEEPINTERVAL option can be used to affect this value for a given socket.

      Solution

      Add a JDK-specific socket option that supports setting TCP_KEEPIDLE, TCP_KEEPCOUNT, TCP_KEEPINTERVAL, on platforms that support it. The option can be set/get through the existing set/getOption methods on Socket and NetworkChannel.

      Specification

      To jdk.net.ExtendedSocketOptions, add the following new socket options:

        
        /**
         * Keep-Alive idle time.
         *
         * The value of this socket option is an {@code Integer} that is the number
         * of seconds of idle time before keep-alive initiates a probe. The socket
         * option is specific to stream-oriented sockets using the TCP/IP protocol.
         * The exact semantics of this socket option are system dependent.
         *
         * When the {@link java.net.StandardSocketOptions#SO_KEEPALIVE
         * SO_KEEPALIVE} option is enabled, TCP probes a connection that has been
         * idle for some amount of time. The default value for this idle period is
         * system dependent, but is typically 2 hours. The {@code TCP_KEEPIDLE}
         * option can be used to affect this value for a given socket.
         */
        public static final SocketOption TCP_KEEPIDLE
                = new ExtSocketOption("TCP_KEEPIDLE", Integer.class);
      
        /**
         * Keep-Alive retransmission interval time.
         *
         * The value of this socket option is an {@code Integer} that is the number
         * of seconds to wait before retransmitting a keep-alive probe. The socket
         * option is specific to stream-oriented sockets using the TCP/IP protocol.
         * The exact semantics of this socket option are system dependent.
         *
         * When the {@link java.net.StandardSocketOptions#SO_KEEPALIVE
         * SO_KEEPALIVE} option is enabled, TCP probes a connection that has been
         * idle for some amount of time. If the remote system does not respond to a
         * keep-alive probe, TCP retransmits the probe after some amount of time.
         * The default value for this retransmission interval is system dependent,
         * but is typically 75 seconds. The {@code TCP_KEEPINTERVAL} option can be
         * used to affect this value for a given socket.
         */
        public static final SocketOption TCP_KEEPINTERVAL
                = new ExtSocketOption("TCP_KEEPINTERVAL", Integer.class);
      
        /**
         * Keep-Alive retransmission maximum limit.
         *
         * The value of this socket option is an {@code Integer} that is the maximum
         * number of keep-alive probes to be sent. The socket option is specific to
         * stream-oriented sockets using the TCP/IP protocol. The exact semantics of
         * this socket option are system dependent.
         *
         * When the {@link java.net.StandardSocketOptions#SO_KEEPALIVE
         * SO_KEEPALIVE} option is enabled, TCP probes a connection that has been
         * idle for some amount of time. If the remote system does not respond to a
         * keep-alive probe, TCP retransmits the probe a certain number of times
         * before a connection is considered to be broken. The default value for
         * this keep-alive probe retransmit limit is system dependent, but is
         * typically 8. The {@code TCP_KEEPCOUNT} option can be used to affect this
         * value for a given socket.
         */
        public static final SocketOption TCP_KEEPCOUNT
                = new ExtSocketOption("TCP_KEEPCOUNT", Integer.class);
        
      

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              robm Robert Mckenna
              alanb Alan Bateman
              Michael McMahon
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              Dates

                Created:
                Updated:
                Resolved: