What's the difference with childprocess.fork between cluster.fork

Read the docs: child_process.fork vs cluster.fork.

The difference between cluster.fork() and child_process.fork() is simply that cluster allows TCP servers to be shared between workers. cluster.fork is implemented on top of child_process.fork.

http://nodejs.org/api/cluster.html

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1. can I pass arguments to cluster.fork

Not according to the docs, and:

> var cluster = require('cluster')
undefined
> cluster
{ isWorker: false,
  isMaster: true,
  fork: [Function],
  _startWorker: [Function],
  _getServer: [Function] }
> cluster.fork.length
0

(a function's length is its number of formal parameters). Use message passing instead.

2. can I listen on same port or unixsock for ChildProcess create by child_process.fork

Presumably yes, since cluster.fork is implemented on top of child_process.fork. However, there is a reason that cluster.fork already exists, if you want to listen on the same port.