/trazi-city-pop

Primary LanguageJavaScript

Introduction

This project provides a service that allows clients to query for the population numbers of cities, and update populations numbers for cities.

To get started, run npm install to install the project's dependencies.

A fairly comprehensive test suite is included that works on Unix-like platforms. These tests can be run via npm test.

To start the server, run npm start. A new server will be started on the local address 127.0.0.1 (::1) and port 5555. Once started, queries can be issued to it like so:

$ curl -v 127.0.0.1:5555/api/population/state/Alabama/city/Marion
{"population":3178}
$ curl -v -X PUT -d 1 127.0.0.1:5555/api/population/state/Alabama/city/Marion

Note: the special string "boom" can be supplied as a state name to generate the spec defined 400 error when attempting to write new population data.

The server can be stopped by the ctrl+c key combination in the terminal where it was started.

Details

The service is written with the Fastify framework. As such, it utilizes features of the framework to provide assistance in the business logic and data persistence.

Data is loaded from the included city_populations.csv file via the lib/plugins/city-data.mjs plugin. This plugin parses the CSV file and adds the data to an in-memory object that is modeled in lib/city-data.mjs. This object provides the methods for adding, updating, finding, and persisting population data.

The routes, defined in lib/routes/population/, use a Fastify decorator added by the city data plugin to gain access to the data object. The get route uses this rather simply. The put route is where the interesting parts are defined. This is where we handle persisting data to disk after PUT requests and when the server is stopped.

Benchmarks

System Details

  • Apple M1 Max
  • 32 GB RAM
  • macOS 13.4.1 (22F82)

GET

❯ npx autocannon -d 10 -c 30 -w 3 127.0.0.1:5555/api/population/state/georgia/city/atlanta
Running 10s test @ http://127.0.0.1:5555/api/population/state/georgia/city/atlanta
30 connections
3 workers

-
┌─────────┬──────┬──────┬───────┬──────┬─────────┬─────────┬───────┐
│ Stat    │ 2.5% │ 50%  │ 97.5% │ 99%  │ Avg     │ Stdev   │ Max   │
├─────────┼──────┼──────┼───────┼──────┼─────────┼─────────┼───────┤
│ Latency │ 0 ms │ 0 ms │ 2 ms  │ 2 ms │ 0.14 ms │ 0.48 ms │ 19 ms │
└─────────┴──────┴──────┴───────┴──────┴─────────┴─────────┴───────┘
┌───────────┬─────────┬─────────┬─────────┬─────────┬──────────┬─────────┬─────────┐
│ Stat      │ 1%      │ 2.5%    │ 50%     │ 97.5%   │ Avg      │ Stdev   │ Min     │
├───────────┼─────────┼─────────┼─────────┼─────────┼──────────┼─────────┼─────────┤
│ Req/Sec   │ 35359   │ 35359   │ 39295   │ 41247   │ 39148.81 │ 1510.56 │ 35358   │
├───────────┼─────────┼─────────┼─────────┼─────────┼──────────┼─────────┼─────────┤
│ Bytes/Sec │ 6.79 MB │ 6.79 MB │ 7.54 MB │ 7.92 MB │ 7.52 MB  │ 289 kB  │ 6.79 MB │
└───────────┴─────────┴─────────┴─────────┴─────────┴──────────┴─────────┴─────────┘

Req/Bytes counts sampled once per second.
# of samples: 31

432k requests in 10.01s, 82.9 MB read

PUT

Note: due to a bug in autocannon, these are performed using wrk

❯ wrk -d 10 -c 30 -t 3 -s bench.lua http://127.0.0.1:5555/api/population/state/georgia/city/atlanta
Running 10s test @ http://127.0.0.1:5555/api/population/state/georgia/city/atlanta
  3 threads and 30 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     0.91ms    3.03ms  69.96ms   99.18%
    Req/Sec    15.10k     1.93k   16.82k    94.72%
  455263 requests in 10.10s, 53.40MB read
Requests/sec:  45063.68
Transfer/sec:      5.29MB

Utilizing the bench.lua script:

wrk.method = "PUT"
wrk.body = "1"
wrk.headers["Content-Type"] = "application/x-www-form-urlencoded"