The Socket Io server drops if the tab is inactive

[wistis]

There is a chat. Socket Io server starts and works, if a client connects to it, and then switched to another tab, seconds to 25-30, then after a while if you go back to the tab with the chat, the messages are not sent, if the page is updated it goes when you connect to server scripts we get 504 Gateway Time-out. The server itself works on the source port, but does not display the information. At the time of this connection, Apach consumes up to 100% of CPU.
`var express = require('express');
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io')(server);
var fs = require('fs');
var https = require('https');

server.listen(5000, function () {
console.log('Server listening at port %d', 5000);
});
const opts = {
key: fs.readFileSync('/var/www/httpd-cert/olever/site.key'),
cert: fs.readFileSync('/var/www/httpd-cert/olever/site.crt')
}

var httpsServer = https.createServer(opts, app);
httpsServer.listen(5001, function(){
console.log("HTTPS on port1 " + 5001);
})

io.attach(httpsServer);
io.attach(server);

io.on('connection', (socket) => {
console.log('a user connected');
socket.on('click', function(data) {
console.log(JSON.stringify(data)+'11');

    socket.broadcast.emit('new message', {
        username: socket.username,
        message: data
    });

});


let token = socket.handshake.query.token;
let admin = socket.handshake.query.admin;
    console.log(token);
    socket.join(token);

socket.on(token+'_write', function(msg) {
    console.log( msg['message']);
    if (admin == 1) {

        socket.broadcast.emit(token + '_write', {
            username: token,
            message: msg['message']
        });

    }
});

socket.on('disconnect', function() {
    console.log('disconnect');
});

socket.on(token, function(msg){

 if(admin==1) {
     console.log(msg['mess']);
     socket.broadcast.emit(token, {
         username: token,
         message: msg
     });

 }
    console.log('message: ' + msg);

if(admin==0) {
var XMLHttpRequest = require("xmlhttprequest").XMLHttpRequest;
var xhr = new XMLHttpRequest();

var body = 'my_data=' + encodeURIComponent(JSON.stringify(msg));


xhr.open("POST", '/send_chat', true);
xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xhr.send(body);

}
});
});`

[NoxWorld258]

Made the same kind of test and have the same problem in local.

I asked the server to display a message such as "Ping timeout" on timeout disconnection.
To my surprise, after about 30 minutes of inactivity, the terminal started to lag a lot, then displayed the "Ping timeout" message hundreds of time.

I guess that explains the 100% CPU usage. This is very strange however that when the client comes back the server tries to process all of the timeout messages at once. And supposedly BEFORE allowing the client to reconnect.

If this is a normal / intended behaviour, it should be changed because it prevents the client from reconnecting, and makes the server lag. The timeout messages and errors should be handled one by one as they show up, and not all at once. And it shouldn't prevent the client from reconnecting in any case i think.

I didn't find any workaround yet, but i'm pretty sure there should be a possibility to handle that case with the connection / disconnection event. I think i saw a post about that, where people actually created a new connection to avoid that kind of issue (which is fucked up in my opinions, but it seemed to work).

Edit : there is also a timeout parameter that can be set, maybe we could find a way to set that to infinite or something similar ?

Hope this helps.

[darrachequesne]

For future readers: that is a common browser behavior, and there's nothing we can do on our side.

Documentation: https://socket.io/docs/v3/troubleshooting-connection-issues/