strange leak

var self = this
  , c = 0
  , dels = []
  , o
  , k
  , tim = new Date()

var free = function() {
  var t = new Date()
  if (t - tim > 10000) {
    while (ok = dels.pop()) {
      delete self[ok[0]][ok[1]]
    }
    tim = t
  }
}

var next = function() {
  o = Math.floor(Math.random() * 16).toString()
    + Math.floor(Math.random() * 16).toString()
        
  if (typeof self[o] === 'undefined') self[o] = {}
  
  k = Math.floor(Math.random() * 10000000000).toString()
  
  self[o][k] = ['3523', '2347']
  
  c++
  if (c % 10000 === 0) console.log(c)
  
  dels.push([o,k])
  process.nextTick(function() {
    free()
    next()
  })
}

next()