Round-robin (RR) is one of the algorithms employed by schedulers in computing. Jobs are assigned to each worker in circular order, It’s simple but useful.

I have a web server writing by node just for front-end display, APIs are most holding by back-end servers. So I have 2 functions supporting my structure. The first is health check helping me check whether the back-end server is ready; and the other one is round robin scheduling, to ensure an even distribution.

Most of the time, I need 1:1 distribution, but sometimes there should be a weighting, so I wrote a weighted round robin module in nodejs just like nginx.

For Example, A B C’s weight is 2 1 1, and the result should be

a
b
a
c
a
b
a
c
a
b
a
c
…
The source code is available on GitHub page.