Explicit is Better than Implicit - Part 2: Behaviors
“Explicit is better than implicit” is one of my favorite lines from the Zen of Python. In essence, this guiding principle encourages clarity in code by favor...
2024
Explicit is Better than Implicit - Part 1: Intentions
“Explicit is better than implicit” is one of my favorite lines from the Zen of Python. In essence, this guiding principle encourages clarity in code by favor...
Code Coverage: Misusage and Proper Usage
TL;DRs Blindly aiming for high coverage can degrade test quality as developers may prioritize increasing coverage metrics over writing meaningful, effecti...
Exposing Applications Running in EKS Cluster for External Access
To expose applications running in a Kubernetes cluster in the cloud, you need an additional component to facilitate external access. For clusters in AWS, AWS...
Building Faceted Search using Elasticsearch
Faceted search Faceted search is a type of search that enables users to narrow down search results by applying multiple filters based on predefined facets, w...
Book Review: Code Simplicity by Max Kanat-Alexander
Code Simplicity by Max Kanat-Alexander is an ambitious effort to define a set of principles, rules, and laws for software development. In my opinion, this is...
Dependency Injection and Dependency Inversion
Dependency injection and dependency inversion are two terms that often come together but serve distinct meanings and purposes.
Preventing Flaky Tests and Brittle Tests
Flaky tests and brittle tests are two common pitfalls that make our tests unreliable and hard to maintain. In this post, I will illustrate these concepts wit...
2023
Provision an Amazon EKS cluster with AWS CDK
Amazon EKS (Elastic Kubernetes Service) is a fully managed Kubernetes service that simplifies building, securing, operating, and maintaining Kubernetes clust...
Memory Profiling CPython Applications with Memray
Memory management in modern programming languages is well-abstracted away from programmers. We do not have direct control over how our programs allocate and ...
Explaining the One-Version Rule and Monorepos in the context of Microservices
The organization I am currently working at develops applications built on microservice architecture, and we were trying to follow the internal policy that th...
Property Based Testing with Hypothesis
What is Property Based Testing? Property based testing, which is known to be originated by QuickCheck, is a testing technique which randomly generates test c...
Win 1st Place at AWS GameDay 2023 in Seoul
On April 14, my teammates and I participated in AWS GameDay 2023 and took 1st place. (team name: justintime @buzzni)
Configuring GitOps with Argo CD
In this post, I am going to share my experience of configuring GitOps for a continuous deployment process. (FYI, you may refer to the following content for c...
Scheduling
A CPU scheduler is an operating system module that decides which process in the ready queue is allocated a CPU. It checks all of the tasks in the ready queue...
Thread Design Considerations
Thread Data Structures A user-level threading library has its own user-level thread data structure to represent threads in order to schedule and synchronize ...
Building a Serverless Function using Amazon API Gateway and AWS Lambda
This post is a quick tutorial to build a very simple serverless function using Amazon API Gateway and AWS Lambda.
2022
Consumer-Driven Contract Testing with Pact
Consumer-driven contract testing (or CDC for short) is a testing methodology that ensures that providers are compatible with the expectations that the consum...
Single Responsibility Principle - Explained with Examples
(This post was last updated on December 13, 2024.)
Creating a VPC with AWS CDK: A Guide for Former CloudFormation Users
The AWS CDK(Cloud Development Kit) is an open-source framework to provision and manage the cloud resources using familiar programming languages.
pthreads
pthreads stands for POSIX Threads which is the de facto standard threading related API that operating systems need to support for thread managements. Almost ...
Threads and Concurrency
A traditional process has a single execution context that can only execute at one CPU at a given point of time. If a process can have multiple execution cont...
Processes
Definition A process is an instance of an executing program. It is also referred to as a “task” or “job”.
Operating System Overview
Definition An operating system, or OS, is just a software that abstracts and arbitrates the underlying hardware components in computer systems.
2021
Redlock: Distributed Lock Manager with Redis
A couple years ago, I discovered an issue caused by a race condition that occured in the backend application I was maintaining. So I implemented a simple dis...
Liskov Substitution Principle and Circle-ellipse Problem
The circle-ellipse problem, or square–rectangle problem, illustrates a limitation of OOP (object-oriented programming). Specifically, it violates the Liskov ...
Python Descriptors
A descriptor in Python is a class attribute which defines any of the special methods: __get__(self, obj, owner=None) -> value __set__(self, obj, valu...
Timsort
Most programmers would be familiar with some fundamental sorting algorithms such as bubble sort, selection sort, insertion sort, and merge sort. Then which a...
How Kubelet Garbage Collection Fails (The Outbreak of Evicted Pods)
Since I’ve bootstrapped a K8s cluster and been administrating all by myself, I’ve encountered many problems and I have had to solve them on my own. One chall...
Peformance Comparison between Flask and Sanic
Flask and Sanic Flask is one of the most popular micro web frameworks written in Python and I love using it for developing a wide range of web services becau...
Understanding HTTP with netcat
Any web developer would know about HTTP buy may not be familiar with the exact syntax of it because it’s abstracted by the network libraries.