Send data with node-fetch in node.js to Pure Data (Pd) result in ETIMEDOUT

Question

I'm building a sound installation that downloads weather information and translates that to sound. Also, I've made a simple html site in p5.js that enables the user to turn off the volume and use a slider to play music. Everything is neatly integrated in a node.js server.

The data is sent from a sketch.js file to a server.js file using socket.io. Data from the server is sent to Pure data with a node package called "node-fetch", where it's received with a [netreceive] object. All of this is done over localhost (http://"ip-adress":port).

On to the problem: Everything runs great, but after about three to six hours, the node server seem to lose connection with Pd (Pure data) and terminates. I restart, and the same thing happens. The error message reads:

Sep 24 14:55:52 raspberrypi bash[7530]: (node:7561) UnhandledPromiseRejectionWarning: FetchError: request to http://192.168.1.219:3558/ failed, reason: connect ETIMEDOUT 192.168.1.219:3558
Sep 24 14:55:52 raspberrypi bash[7530]:     at ClientRequest.<anonymous> (/home/pi/Documents/pd2_repository/node_modules/node-fetch/lib/index.js:1455:11)
Sep 24 14:55:52 raspberrypi bash[7530]:     at ClientRequest.emit (events.js:198:13)
Sep 24 14:55:52 raspberrypi bash[7530]:     at Socket.socketErrorListener (_http_client.js:401:9)
Sep 24 14:55:52 raspberrypi bash[7530]:     at Socket.emit (events.js:198:13)
Sep 24 14:55:52 raspberrypi bash[7530]:     at emitErrorNT (internal/streams/destroy.js:91:8)
Sep 24 14:55:52 raspberrypi bash[7530]:     at emitErrorAndCloseNT (internal/streams/destroy.js:59:3)
Sep 24 14:55:52 raspberrypi bash[7530]:     at process._tickCallback (internal/process/next_tick.js:63:19)
Sep 24 14:55:52 raspberrypi bash[7530]: (node:7561) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 735)

I have no idea of where to start looking for answers: Is the fault in my sketch.js, in the server.js, in Pd, or has it got something to do with the internet? It shouldn't be a proxy problem since I'm running it on localhost, right?

Here's a sample from my sketch.js:

function setup() {
  noCanvas();

  // Start a socket connection to the server
  socket = io.connect(url + ':3000');

async function getISS() {
    const response = await fetch(api_url);
    const data = await response.json();
    console.log(data.timeSeries[2].validTime);

    var smhiData = {
      pcat: data.timeSeries[2].parameters[2].level,
      sunUp: 6,
      sunDown: 20
    };
    socket.emit('smhiToPd', smhiData); 
}

And here's a sample of the server:

io.sockets.on('connection', newConnection);

// We are given a websocket object in our function
function newConnection(socket) {
    console.log('We have a new client: ' + socket.id);
socket.on('smhiToPd', smhi);

    async function smhi(data){
        pcat = data.pcat;

        fetch("http://" + ip + ":" + 3558, {
            method: "PUT", 
            body: ";pcat " + pcat + ";"
        });
    }
}

And this is what it looks like in Pd: Netreceive-object listening to port 3558

Pd and Node is started with a systemd startup script.

Some information about Pd: Version: 0.51-2. Flags: -rt and -nogui. Audiorate: 48 kHz Blocksize: 64 Delay: 512.

Computer is a Raspberry Pi 4 running Raspbian. The Pd process is running at about 15-35 % CPU.

PS Very grateful for any help. Please note, I am a beginner and my programming skills and knowledge are very limited. I'll try my best to make sense of any answers or ideas you might have!

PPS I know I have yet to implement a .catch in the server. I just implemented it in my code and I am waiting for another crash.

EDIT: Currently, bash is spitting out this error message, at least 50 messages/second and pd is running close to 100% CPU.

Sep 25 07:46:52 raspberrypi bash[10566]: netreceive: accept failed
Sep 25 07:46:52 raspberrypi bash[10566]: netreceive: accept failed
Sep 25 07:46:52 raspberrypi bash[10566]: netreceive: accept failed
Sep 25 07:46:52 raspberrypi bash[10566]: netreceive: accept failed
Sep 25 07:46:52 raspberrypi bash[10566]: netreceive: accept failed
Sep 25 07:46:52 raspberrypi bash[10566]: netreceive: accept failed
Sep 25 07:46:52 raspberrypi bash[10566]: netreceive: accept failed
Sep 25 07:46:52 raspberrypi bash[10566]: netreceive: accept failed
Sep 25 07:46:52 raspberrypi bash[10566]: netreceive: accept failed

I think I found the source code for the [netreceive]. Here's the part about the "accept failed". Can anyone make sense of this?

static void netreceive_connectpoll(t_netreceive *x)
{
    int fd = accept(x->x_connectsocket, 0, 0);
    if (fd < 0) post("netreceive: accept failed");
    else
    {
        t_socketreceiver *y = socketreceiver_new((void *)x, 
            (t_socketnotifier)netreceive_notify,
                (x->x_msgout ? netreceive_doit : 0), 0);
        sys_addpollfn(fd, (t_fdpollfn)socketreceiver_read, y);
        outlet_float(x->x_connectout, ++x->x_nconnections);
    }
}

Answer 1

I found the answer to what's causing the connection to close and the computer to freeze. It's that Pd's [netreceive] opens up a new connection every single time it receives a new message. This works fine for a couple of connections, but as the number of connection increases, the load gets heavier and heavier, eventually causing the computer to freeze.

Why does Pd open up a new connection every time it receives data? Not sure. Has it got something to do with the TCP protocol?