README.md

Recursive Fibonacci

This example implements an algorithm to calculate Fibonacci numbers in a distributed recursive way.

Recursion is supported on a single thread by JavaScript language, how if we want to involve multiple JavaScript threads to collaborate on a task? Since recursion will block caller until callee returns, dispatching recursive tasks to other threads will soon block all threads, which leads to deadlock. This example demonstrates recursive dispatching using Promise, that is, current thread will continue to serve other tasks while its sub-tasks are pending, and resume work once sub-tasks complete.

Please note that this example is to demonstrate the programming paradigm, while itself is NOT performance efficient, since each worker does too little CPU operation (simply '+') and major overhead is on communication.

How to run

  1. Go to directory of "examples/tutorial/recursive-fibonacci"
  2. Run "npm install" to install napajs
  3. Run "node recursive-fibonacci.js"

Program output

Table below shows statistics of calculating Nth Fibonacci number by a napa zone with 4 workers.

        Nth     Fibonacci       # of workers    latency in MS
        -----------------------------------------------------------
        10      55              4               46
        11      89              4               47
        12      144             4               47
        13      233             4               47
        14      377             4               94
        15      610             4               140
        16      987             4               266

We got results under environment:

Name Value
Processor Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz, 2000 Mhz, 6 Core(s), 12 Logical Processor(s)
System Type x64-based PC
Physical Memory 32.0 GB
OS version Microsoft Windows Server 2016 Datacenter