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WLED

Today I learned about the amazing WLED project: https://github.com/Aircoookie/WLED

All you need to do is flash their binary to an ESP32 and it will bring up a WIFI access point that allows you to control the LEDs through an app or web page.

Microservice Communication

I’ve been learning more about async communication between microservices and came across this article that talks about some of the trade-offs between sync and async communication: https://dzone.com/articles/patterns-for-microservices-sync-vs-async

Summary

Sync

Pros

  • “synchronous calls are simpler to grasp, debug and implement”

Cons

  • “A temporary burst at one component can flood other services with requests.”
  • Risk of Cascading Failures (domino effect of failures if one service experiences an otuage)
  • tighter coupling (requires endpoint versioning in the owning service)

Async

Pros

  • “removes the need to wait for a response thereby decoupling the execution of two or more services”
  • “deals better with sporadic bursts of traffic”

Cons

  • “Asynchronous systems tend to be significantly more complex than synchronous ones.”
  • “consumers need to adapt to work with an asynchronous system”
  • “the message bus the Achilles heel of the system as it remains a central point of failure”
  • Eventual Consistency (potentially out of date data)

Python - Mypy

My new job has me working on a larger codebase than previous jobs, and it’s also my first time using mypy.

I’m starting to understand why Guido’s work on mypy had a lot to do with Dropbox’s Python 3 migration. Dropbox wrote an article with details on how they used mypy on their “4 million lines of Python”. With that much code, I can understand why they needed to treat code like “cattle, not pets”.

Python 3 disallows some comparisons with None types, makes huge changes to strings/bytes, and has many other changes involving types. When your codebase is massive, you have to reach for automated tooling to consistently find and prevent those bugs. With the same tooling you can also prevent entire categories of other bugs from reaching production. The type hints can also be helpful documentation. For those reasons and more, I think implementing type hints on a large codebase like Dropbox’s will definitely be worth it in the long run.

It has me wondering if I should have been taking the extra time to use type hints and checking (or a statically typed language) this whole time. Was going without type hints one less distraction? Or will be the price be paid in maintenance difficulties and bug fixes later?

At this point, not much of the Python ecosystem has type hints (not even Python 2 compatible comment-style type hints). I’m starting to think it would be a good use of time to work on changing that.

Ruby - Jekyll

I migrated this blog from blogger/blogspot to a static site generated with Jekyll and hosted with Netlify.

This blog post describes the process: http://joshualande.com/jekyll-github-pages-poole

Initially, I started using Python’s Pelican, but pelican-import (pelican’s tool for migrating from blogger) doesn’t work as well as jekyll-import. It turned comments into posts and threw exceptions while processing draft posts without content. Also, the first docs that show up on google for Pelican aren’t the latest docs. This causing issues when I followed the old docs that said to use Python 2.7, but Pelican only supports Python 3.6+ now.

Django - Duplicate Unformatted Logs

Recently I worked on a bug that was causing duplicate unformatted log messages to appear in a Django app's logs. I made a repository that demonstrates the issue: https://github.com/pawl/django_duplicate_unformatted_logs_example

The problem was caused by an accidental call to logging.info (without using logging.getLogger to get a specific logger) while the root logger isn't already configured.

The solution ended up being to get rid of the accidental calls to logging.info and configuring the root logger to prevent it from accidentally happening again. I go into more details in that repo.