OSX socket programming

Why won't the socket open in bulk at once?

I am using Intel macOS Big Sur 11.5.1

The connection test is being conducted with the local docker nginx server.

We are using Golang to conduct tests with the following codes:

func TestBulkConnection(t *testing.T) {
    var worker = 1000
    var wg sync.WaitGroup
    for i := 0; i < worker; i++ {
        wg.Add(1)
        //time.Sleep(time.Millisecond * 10)

        go func(id int) {
            conn, err := net.Dial("tcp", "localhost:9000")
            if err != nil {
                log.Fatal(err)
            }
            defer conn.Close()
            defer wg.Done()

            fmt.Println("waiting... ", id)
            time.Sleep(time.Second * 30)

        }(i)
    }

    wg.Wait()
}

1000 goroutine connecting to nginx only. After the connection, the sleep() function was used to make sure that nothing was done.

The client created 1000 goroutines, but found that only 200 to 300 nginx and connections worked and the rest did not (we confirmed with netstat-anv | grep 9000).

When connecting, it was confirmed that all connections are well established when the sleep() function is executed.

With nginx and client code, when spun from private ubuntu 18.04, the connection was confirmed at once.

I think it's a problem on the nginx server side, but I don't know the cause of the problem.

Is there a difference between Mac and Ubuntu in this test?

Added

let net = require('net');

for (let i = 0; i < 1000; i++) {
    const socket = net.connect({ port: 9000 });
    socket.on('connect', function () {
        console.log('connected to server!');
    });
}

netstat -anv | grep 9000 | wc -l

2000 connection ok

Added

The following links are used to increase the file descriptors of OSX.

https://wilsonmar.github.io/maximum-limits/

In recovery mode, 'csrutil disable' was also executed.

$ ulimit -a
-t: cpu time (seconds) unlimited
-f: file size (blocks) unlimited
-d: data seg size (kbytes) unlimited
-s: stack size (kbytes) 8192
-c: core file size (blocks) 0
-v: address space (kbytes) unlimited
-l: locked-in-memory size (kbytes) unlimited
-u: processes 2048
-n: file descriptors 524288

But still.

$ netstat -anv | grep 9000 | wc -l
287