Summary

Highly scalable and performant job and event publisher for IOT systems that need to store events in a DB to fire at a specific time. Many instances of this publisher can be stood up in parallel next to each other and run in tandem without DB blocking or publishing the same message twice.

Basic In Code Setup

A simple setup would be similar to what exists in the LocalApp project and is as follows:

using JobPublisher.Database;
using JobPublisher.Mqtt;
using JobPublisher.Config;
using Microsoft.Extensions.Logging;

...

PostgresConfig pgConfig = new PostgresConfig(dbUser, dbPass, dbPort, dbServer, dbName);
MqttClientConfig mqttConfig = new MqttClientConfig(mqttUser, mqttPass, mqttPort, mqttServer);
PublisherConfig publisherConfig = new PublisherConfig(jobsPerRead, loopFrequencyMs, consumerCount, consumerIndex, maxReads);

using ILoggerFactory factory = LoggerFactory.Create(builder => builder.AddConsole());
ILogger logger = factory.CreateLogger("Job-Publisher");

JobPublisher publisher = new JobPublisher(logger, pgConfig, mqttConfig, publisherConfig);
await publisher.Run();

...

These classes can be initialized after downloading the package

Local Testing

Use the provided dockerfile and sql scripts to boot up an instance of this service and watch it publish messages

Boot up local DB and IOT broker

docker-compose up postgres mosquitto

Boot up a single instance of this service

docker-compose up job-publisher-single

Log into the local DB with any IDE and execute the create table and index queries, and then insert jobs to fire as you wish!

Testing

Performance Profiling

In order to stress test the system and see its CPU / MEM usage we can leverage docker

First, boot up local instances of the DB and IOT broker

docker-compose up postgres mosquitto

Second, start up multiple instances of the consumer

docker-compose up --build job-publisher-parallelized-one job-publisher-parallelized-two job-publisher-parallelized-three job-publisher-parallelized-four job-publisher-parallelized-five

Third, hook into container usage using docker

docker stats job-publisher-parallelized-one job-publisher-parallelized-two job-publisher-parallelized-three job-publisher-parallelized-four job-publisher-parallelized-five

Last, pump as many jobs into the database as you see fit by using the provided sql scripts, for example

-- Bulk add for stress test
INSERT INTO jobs (
	topic,
	payload,
	fire_at,
	processed,
	processed_at
)
SELECT
	'job/test/topic',
	'{"Job": "' || x.test_data || '"}',
	now(),
	false,
	null
FROM generate_series(1,20000) AS x(test_data);

Performance stats

Single Consumer

Jobs per read: 100 Loop interval: 50ms

Results: Jobs published per minute: 45k Peak CPU usage of container: 50% Peak memory usage: 39mb

5 Parallelized Consumers

Jobs per read: 100 Loop interval: 50ms

Results: Jobs published per minute: 160k Peak CPU usage of container: 42% Peak memory usage: 39mb