How Can I or Should I Fine Tune Node.js/Socket.io Chat App So It Doesn't Drag Down My Entire Website/Server? – CentOS

I built a chatroom w/ NodeJs using, socket.io, mysql2 & express packages. It’s extremely dynamic including public chats, private messaging, and other unique features to make it lively, ie real time updates, notifications, etc.

Originally built and tested on a dummy domain and was working perfectly fine. And then I moved it over to my main website domain when finished. Now that it is, I’m experiencing horrible site load speeds. However, both domains (the test domain site and main live site were on the same server).

The server; 2x Intel® Xeon® Processor E5-2697 v4, 64GB RAM, 4x 480GB SSD, HW RAID storage, Network port 1 Gbps, 2 ipv4 addresses, bandwidth 50 TB, Centos 7, cpanel included and have.
About 1000 users actively use the website/chat.
The chatroom is negatively impacting the rest of the site and slowing it all down. Initial server response is roughly 14 seconds, but in worst case scenarios has been as long as 30+ seconds. Whereas on the test domain it was only literally 1 second. It goes without saying I should expect as good a load times as on the original test domain as a live one with real users, but this bad? I digress.

I ran speed tests. The results of those tests kept reporting back to me the initial load time was too long and literally said nothing in specific to point me to what the problem was so I assumed it was MYSQL, php, among other things. I optimized it all to the best of my ability. But after the site kept dragging, I still kept getting the same results. I finally removed things from the site one by one and when I removed the chat, the site loaded perfectly fine. It was odd, because none of the speed tests pointed to the chat or node in particular being the reasoning.

So then I optimized Node in the following ways.
-I tried adding pooling to the sql connection, trying different numbers, from 5-500,
-I tried adding a PoolManager to the database connection.
-I removed the ability for all visitors to stay connected to our node server. They’re socket connection would be terminated if they didn’t mean certain cretia.
-I added some parallelize to the code. To run some functions that called the database.
-I made sure to add keys and avoided long sql queries, used LIMIT, and avoided *

Put it back on the site, still the same horrible load times.

After some research I am hopeful (but still only guessing) that the following may be cause for concern;

-The server is defaulting to polling. So maybe that might be causing an issue.
Since I assume everytime it polls it has to connect and disconnect from the database server which will cause a pretty big delay since I read that a lot of issue are there.
-I tried to fixing the polling but have not been able to get it to work. I tried forcing transport:

[‘websocket’]

, with all different types of settings, CORS, secure, and etc.

I read into possibly using Redis for caching and I think it can be implemented in some areas for sure. But with how lively the chat is. Cache might be limited in how often it can be used.

If there are any problems with my own code I might guess it is here.

//server
const f = require('./functions.js');
const db = require('./db.js');
const cookie = require('cookie');
const http = require("http");
const express = require("express");
const { Server } = require("socket.io");


const port = 3000;
const appBaseUrl = "/node";
const socketBaseUrl = "/node/socket";

global.last_message_time = new Date('1995-12-17T03:24:00');


// Create the server and socket
const expressApp = express();
const nodeServer = http.createServer(expressApp);
const socketIo = new Server(nodeServer, {
    path: socketBaseUrl,
});


//client 
const chat = io.connect("domain.com", {path: "/node/socket"});

But at the end of the day I am still at a loss and so I look to you and throw myself at the mercy of StackOverflow. Opinions, feedback and ideas as to why the chat is not playing nicely with my website would be more appreciated than you know. Thank you in advance and I look forward to hearing from you.

——————————Update

@Gaëtan Boyals – the additional code you asked for concerning where messages are handled, below.

let chats = []
            await db.getMessages(data.id, user.user_id, user.isAdmin, 'user')
            .then(response=>{
                chats = response.reverse();
            }).catch((err)=>{
                console.log(err);
            })

            let chats_html = [];
            for(let chat of chats){
                chat.message_type = chat.type;
                chat.images       = [];
                chat.small        = [];
                if(chat.type=='photos'){
                    let encoded = JSON.parse(chat.message);
                    for(let small of encoded){
                        let j = f.createToken(small);
                        chat.small.push(j+ "?height=150");
                        chat.images.push(j)
;
                    }
                }
                //might cause issues later so see what's up here.
                
                chat.emojis       = await db.getEmojiReactions(1, chat.id);
                chat.avatar       = f.createToken(chat.avatar);
                chats_html.push(f.createMessage(chat, user.user_id, user.user_type)); 
            }
            let chat_info = await db.getPrivateRoom(data.id, user.user_id);
            socket.join(chat_info);
            user.current_room = data.id;
            user.current_type = 'user';
            user.room = chat_info;

            let send = {chats:chats_html};
            socketIo.to(socket.id).emit('get-chat', send);

            let best_badge = await db.bestBadge(data.id);
            let user_1     = await db.getUserFromId(data.id);
            user_1.badge   = best_badge ? best_badge.badge_id:false;
            user_1.avatar  = f.createToken(user_1.avatar);
            
            let group_user_html = [];
            group_user_html.push(f.rightSideUsers(user_1));
            group_user_html.push(f.rightSideUsers(user));
            socketIo.to(socket.id).emit('right-users', group_user_html);

if(user.current_room != 0){
            let isMuted = false;
            if(data.type=='group'){
                isMuted = await db.isMuted(user.user_id, data.id);
            }
            if(!isMuted){
                data.user_id = user.user_id;
                data.to      = data.id;
                if(data.message_type == 'photos'){
                    data.message = JSON.stringify(data.message);
                }
                
                if(user.user_id==0){
                    data.guest = user.username;
                }
                db.newMessage(data)
                .then((response)=>{
                    if(response){
                        
                        if(data.type=='group'){
                            db.setChatMeta(response, 'group', data.id,user.user_id);
                        }else{
                            db.setChatMeta(response, 'user', data.id,user.room);
                        }
                        

                        data.id      = response;
                        data.chat_id = response;
                        let html     = f.createMessage(data, user.user_id, user.user_type);
                         
                        let new_data = f.createRightData(data);
                        new_data.message = new_data.message.replace('<br />', '');
                        let uni = user.room;
                        let send = {html:html, id:uni,type:data.type}
                        if(data.message_type == 'video'){
                            setTimeout(()=>{
                                socketIo.in(user.room).emit("new-message",send);
                                socketIo.emit('refresh');

                            }, 5000)
                            
                        }else{
                            console.log(user.room);
                            socketIo.in(user.room).emit("new-message",send);
                            socketIo.emit('refresh');

                        }
                        
                    }
                }).catch((err)=>{
                    console.log(err)
                })
            }else{
                socketIo.to(socket.id).emit('muted')
            }
        }

GET and SET messages.