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Thread: Amount of Sockets drops over time

  1. #1
    Join Date
    Nov 2011

    Amount of Sockets drops over time

    Hi there,

    I have a small app (dotnet) which sends +1000 async requests per second to different servers/urls.

    The main issue is that over about 5 minutes the amount of ESTABLISHED sockets drops from +1000 to 5-10 (and there are no a lot of WAIT/SYN sockets etc.)
    until it stops sending requests at all. If i close the app and start it again then it starts sending +1000 requests again and then slowing down and so on over and over.

    Any ideas on what may cause it?

    Ubuntu 20.04/22.04 cloud-base images

    i do track sockets and their states using the command:
    netstat -n | awk '/^tcp/ {t[$NF]++}END{for(state in t){print state, t[state]} }'

    Last edited by okarpov; August 7th, 2023 at 12:33 PM.

  2. #2
    Join Date
    Nov 2011

    Re: Amount of Sockets drops over time

    This is the code to create sockets (it has 3 public IPs on the same eth0):

                    socket = new Socket(ip.AddressFamily, SocketType.Stream, ProtocolType.Tcp)
                        // Turn off Nagle's algorithm since it degrades performance in most HttpClient scenarios.
                        NoDelay = true,
                        ReceiveBufferSize = respbufferSize,
                        SendBufferSize = reqbufferSize,
                        ExclusiveAddressUse = false,
                        Ttl = time_out,//64
                    socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
                    await socket.ConnectAsync(ip, context.DnsEndPoint.Port, cancellationToken).ConfigureAwait(false);
                    NetworkStream ns = new NetworkStream(socket, ownsSocket: true);
                    return ns;
    also i do set the following system params:
    /sbin/sysctl -w net.core.somaxconn=65536
    /sbin/sysctl -w net.ipv4.ip_local_port_range="1024 65535"
    /sbin/sysctl -w net.ipv4.tcp_tw_reuse=1
    /sbin/sysctl -w net.ipv4.tcp_fin_timeout=15
    Last edited by okarpov; August 7th, 2023 at 12:33 PM.


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