As socket.io 2.0 is not backward-compatible (https://socket.io/blog/socket-io-2-0-0/) I'm curious what is the suggested procedure of production upgrade.
The problem is there are many people connected to a server when deployment takes place, and after deployment is completed they are still most likely using old socket.io client trying to reconnect.
Backward-incompatibility in my case (1.4.5 -> 2.0) turns out to be pretty troublesome as old client keeps sending handshake requests at an insane rate, and a new server keeps shoving them off resulting in huge cpu and ram loads on server.
What's suggested strategy in this case (preferably long-term, i.e. taking care of future updates too)? It's not first socket.io backwards-incompatible release and I have a strong feeling there already good practices at work.
Thank you in advance,
Vasiliy Naumov
I'll probably gonna resort to adding a "connect_error" listener on a socket, which is triggered with parser error when 1.4.5-compatible socket.io client tries to connect to 2.0 socket.io server, from there I'll reload the page and let the browser to load fresh javascript including a newer socket.io client like so:
socket.on('connect_error', function (error) {
if (error.code === 'parser error') {
// potential socket.io protocol update
socket.io.reconnection(false); // stop reconnection attempts
socket.disconnect();
// additional check in case there is no actual socket.io client update, but rather some other reason for parser error being thrown
var upgradeCheckedAlready = window.sessionStorage.getItem('socket.io-upgrade-check');
if (!upgradeCheckedAlready) {
window.sessionStorage.setItem('socket.io-upgrade-check', 1);
window.location.reload();
}
}
})
