clusterpi.js

//
// clusterpi.js
// Neil Gershenfeld 11/23/18
// pi calculation benchmark
// pi = 3.14159265358979323846
//
const cluster = require('cluster')
const points = 1e8
if (cluster.isMaster) 
   master()
else
   child()
function master() {
   var processes = require('os').cpus().length
   var tstart = Date.now()/1000
   for (var i = 0; i < processes; i++)
      cluster.fork()
   var index = 0
   var pi = 0
   var results = 0
   for (const id in cluster.workers) {
      var worker = cluster.workers[id]
      worker.on('message',(result) => {
         pi += result
         results += 1
         if (results == processes) {
            var tend = Date.now()/1000
            var mflops = (processes*points)*5.0*1e-6/(tend-tstart)
            console.log('pi: '+pi)
            console.log('time: '+(tend-tstart).toFixed(1)+'s')
            console.log('processes: '+processes)
            console.log('estimated MFlops: '+mflops.toFixed(1))
            process.exit()
            }
         })
      function send(index) {
         return function() {
            worker.send(index)
            }
         }
      worker.on('online',send(index))
      index += 1
      }
   }
function child() { 
   process.on('message',(index) => {
      var a = 0.5
      var b = 0.75
      var c = 0.25
      var sum = 0
      var start = 1+points*index
      var end = points*(index+1)
      for (var i = start; i <= end; ++i)
         sum += a/((i-b)*(i-c))
      process.send(sum)
      })
   }