When using socket.io with Node v0.11.14, it errors out immediately when just doing require('socket.io") in a worker with the following error. Note that I tested this various ways and the it's reproducible everytime. Try the samplecode of the sticky-sessions module for example (https://github.com/indutny/sticky-session).
Error: C:\Users\me\Desktop\NodeJS Testing\node_modules\socket.io\node_modules\socket.io-client\node_modules\engine.io-client\lib\transports\polling.js:23 var xhr = new XMLHttpRequest({ agent: this.agent, xdomain: false }); ^ TypeError: Cannot read property 'agent' of undefined at C:\Users\me\Desktop\NodeJS Testing\node_modules\socket.io\node_modules\socket.io-client\node_modules\engine.io-client\lib\transports\polling.js:23:45 at Object. (C:\Users\me\Desktop\NodeJS Testing\node_modules\socket.io\node_modules\socket.io-client\node_modules\engine.io-client\lib\transports\polling.js:25:3) at Module._compile (module.js:460:26) at Object.Module._extensions..js (module.js:478:10) at Module.load (module.js:355:32) at Function.Module._load (module.js:310:12) at Module.require (module.js:365:17) at require (module.js:384:17) at Object. (C:\Users\me\Desktop\NodeJS Testing\node_modules\socket.io\node_modules\socket.io-client\node_modules\engine.io-client\lib\transports\polling-xhr.js:6:15) at Module._compile (module.js:460:26)