Why can only 63 client connections be created for a Spring Boot instance?

[QUANGUANGYAO]

I introduced the socket.io-client dependency in my local Spring Boot project and simulated the creation of socket clients through a for loop. However, the maximum number of successful creations was 63, and the 64th one could not connect successfully. What is the problem?

`package com.example.socketioclient.config;

import io.socket.client.IO;
import io.socket.client.Socket;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

@component
@slf4j
public class SocketIOManager {

private final Map<String, Socket> socketClientList = new HashMap<>();

@Value("${socket.server.url}")
private String url;

public void startClients(int numberOfClients) {
    for (int i = 0; i < numberOfClients; i++) {
        createAndConnectClient(i);
        try {
            Thread.sleep(1000L);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }
}

private void createAndConnectClient(int i) {
    try {
        log.info(">>>>>> createAndConnectClient 开始");

// String SERVER_URL = "http://172.14.144.69:9092/";
IO.Options options = IO.Options.builder().setPath("/socket.io/").build();

        Socket client = IO.socket(url, options);
        // 监听连接事件
        client.on(Socket.EVENT_CONNECT, args1 -> {
                System.out.println((i+1) + " : 我自己连上服务端了：" + client.id()
                        + ", 超时时间= " + client.io().timeout());

                socketClientList.put(String.valueOf(i+1), client);
        });

        // 监听自定义事件
        client.on("cat", args2 -> {
                System.out.println("我从服务端的cat获取到消息: " + Arrays.toString(args2));
        });

        // 监听自定义事件
        client.on("dog", args3 -> {
                System.out.println("我是客户端: " + client.id() + "，从服务端的dog获取到消息: " + Arrays.toString(args3));
        });
        // 监听自定义事件
        client.on("init", args3 -> {
            System.out.println("我是客户端: " + client.id() + "，从服务端的init获取到消息: " + Arrays.toString(args3));
        });

        // 监听断开连接事件
        client.on(Socket.EVENT_DISCONNECT, arg -> {
            System.out.println("我从服务端断开了：" + client.id() + ": " + Arrays.toString(arg));
        });

        client.on("connect_error", error -> {
            System.out.println("连接失败：" + Arrays.toString(error));
        });
        // 连接到服务器
        client.connect();

        log.info(">>>>>> createAndConnectClient 结束；clientId= " + (i+1));
    } catch (Exception e) {
        e.printStackTrace();
    }
}

}
`
Above is my code，can anyone help me?