Latest Socket.io and pm2 causing issues when using -i max

[DPerkunas]

When I launch my app.js file via pm2 start app.js -i max I get the following error on client end
" failed: Connection closed before receiving a handshake response "

when I launch the app.js via "pm2 start app.js" it works fine.

I utilize socket.io in my application on apache. The error logs are empty, but I do notice that it emits a console.log("hello world"); twice upon start from each start up on each of the cores. The websocket then keeps connecting and disconnecting.

One thing I think it could be, is that it's supposed to be "stateless", and I hold a list of online users in users = {};

But why would it work when it's only one CPU vs 4?

[rlidwka]

if you're using more than one cpu, users can hit different processes with their requests

try to keep shared state somewhere, in redis for example

[DPerkunas]

So it WAS because of my not following of "stateless". Gotcha, gotta move that user list to redis. Silly me. Thanks.

Edit: Unitech, if you can also check this out, it'd be great. Now that I re-read my own post and tested, it still doesn't make sense to me why not being stateless would cause socket.io not to be found. It would make sense for the app to crash, but not to not find socket.io. Thanks.

[Unitech]

Cluster module doesn't play well with Socket.io 1.x

They ask to do sticky load balancing in order to redirect each user to the same process (http://socket.io/blog/introducing-socket-io-1-0/#scalability) and the Node cluster module does not permit this.

The first solution I see is to fork_mode processes and attributing them different port (via JSON conf). Then with Nginx to do the sticky load balancing (http://socket.io/docs/using-multiple-nodes/#nginx-configuration)

The second solution would be to use the https://github.com/indutny/sticky-session, but unfortunately I can't embed it in PM2.

In conclusion I don't really like this latest socket.io version, as it break the stateless paradigm.

[rlidwka]

sticky-session looks fishy, I mean you can't reconnect with different ip address for example.

But they do recommend redis as the second option, what's wrong with that?

[Unitech]

If I understood well, the redis stuff is about passing events between processes (http://socket.io/docs/using-multiple-nodes/#passing-events-between-nodes)

And as written on the scalability page:
Instead of storing and/or replicating data across nodes, Socket.IO is now only concerned with passing events around.
So each process is only concerned with his very own connections

[DPerkunas]

So we'll leave it at, Socket.IO is the issue, pm2 is fine and nothing we could do about it. Sticky-Session throws a random error after using it for ever so long according to some posts. This is something to be discussed with Socket.IO. Thanks guys.

[soyuka]

Please try to link socket.io issues to this thread so that we might follow them.

Closing this as a non-pm2 issue, feel free to comment or discuss here.

[handleror]

I got same issue! If I did try to run single instance it worked fine, but got a problem for multiple instances.

[lalith-b]

set the protocol to ws from client side while connecting

Client Side - somewhere in js

io.connect({transports: ['websocket']})

Server side - doing this is solving the problem

io.adapter(redis({ host:SETTINGS.redis.host, port: SETTINGS.redis.port }));

Note

It will be a problem with supporting IE and other old browsers as they don't support native websockets, if the application browser compatibility is not an issue this seems a solution.