TypeError：将圆形结构转换为JSON

Question

In my application i am creating an object to keep track of all sockets;

I declare it like:

var sockets = {};

Then when a new socket is created i add the socket to my sockets object;

sockets[socket.name] = socket;

This is required for the logic of my application. And it works perfectly.

The problem i am having is when i want to store the sockets object to a file (for backup purposes) due to my server sometimes restarting. I dont want active sockets to get lost if a restart should happend.

I've tried to save it to a file like this:

    var outputFilenameee = 'sockets.json';

    fs.writeFile(outputFilenameee, JSON.stringify(sockets), function(err) {
        if(err) {
          console.log(err);
        } else {
          console.log("sockets saved in " + outputFilenameee);
        }           

    });

But i am getting this error:

TypeError: Converting circular structure to JSON

Below is a console.log of sockets :

{ '217.208.204.18:63695': 
   { domain: null,
     _events: { data: [Function], end: [Function] },
     _maxListeners: 10,
     _handle: 
      { writeQueueSize: 0,
        owner: [Circular],
        onread: [Function: onread] },
     _pendingWriteReqs: 0,
     _flags: 0,
     _connectQueueSize: 0,
     destroyed: false,
     errorEmitted: false,
     bytesRead: 125,
     _bytesDispatched: 0,
     allowHalfOpen: false,
     writable: true,
     readable: true,
     server: 
      { domain: null,
        _events: [Object],
        _maxListeners: 10,
        _connections: 1,
        connections: [Getter/Setter],
        allowHalfOpen: false,
        _handle: [Object],
        _connectionKey: '4:0.0.0.0:8080' },
     _peername: { address: '217.208.204.18', family: 'IPv4', port: 63695 },
     name: '217.208.204.18:63695' } }

How can i store this in a file?

Answer 1

I dont want active sockets to get lost if a restart should happend

Sorry, but this is unavoidable given the process model of operating systems. Your process's resources including network sockets, open files, memory, etc, are freed and reclaimed by the OS when the process exits.

In order to achieve something like this you would need a separate load balancer or cluster manager to keep the raw sockets alive while one cluster node/worker restarts. You may want to investigate the node.js cluster module, but given you tried to do this by writing sockets to disk, there are some gaps in your understanding of the OS at this level that you may want to study up a bit more before venturing outside of regular application logic.