# learnings Published articles for learnings. This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles. ## What running a Senior Software Engineer Cohort Taught Me DevFeed: [What running a Senior Software Engineer Cohort Taught Me]() Original publisher: [Read original article]() Author: Hemant Pandey Published: 2026-08-23T13:40:11Z Content type: opinion Language: en Sources: [The Hustling Engineer]() Topics: [Software](), [coding]() Tags: [learnings](), [mentoring](), [software](), [software-engineer]() ### AI overview An account of lessons learned from mentoring more than 60 software engineers. ### Source excerpt My learnings after mentoring 60+ Software Engineers ## Read Replica Migration: Lessons and Query Routing Patterns DevFeed: [Read Replica Migration: Lessons and Query Routing Patterns]() Original publisher: [Read original article]() Author: Johanna Larsson Published: 2026-07-21T11:00:45Z Content type: tutorial Language: en Sources: [The incident.io Blog]() Topics: [Databases](), [Database]() Tags: [incident](), [incident-channel](), [incident-management](), [incident-response](), [learnings](), [migrations](), [outage](), [patterns](), [post-mortem](), [read-replica](), [slack-incident]() ### AI overview The article shares incident.io's experience migrating workload to a read replica, including the benefits, operational complexity, and patterns for routing queries between the replica and primary database. ### Source excerpt Our learnings from implementing a product-wide read replica migrations, including some useful patterns for routing queries to replica and primary ## 20 years of Getting Things Done DevFeed: [20 years of Getting Things Done]() Original publisher: [Read original article]() Author: Tom Published: 2025-11-27T00:00:00Z Content type: article Language: en Sources: [Tomasz Gągor]() Topics: [systems](), [DevOps](), [Monitoring](), [backups](), [health checks](), [Disaster Recovery]() Tags: [2](), [advice](), [backup](), [best-practices](), [devops](), [getting-things-done](), [gtd](), [leadership](), [learnings](), [linux](), [monitoring](), [productivity](), [recovery](), [time-management](), [workshop]() ### AI overview A reflection on 20 years of using Getting Things Done, including how external systems shaped the author's work as a system administrator and DevOps engineer. It describes replacing manual backup checks with failure notifications and introducing monitoring and health checks to move operations from reactive to proactive. ### Source excerpt Reflections and practical tips from 20 years using Getting Things Done, plus a short workshop plan for leaders who want actionable routines. ## Notes on The Little Learner: Parameters, Tensors, and Mathematical Operations DevFeed: [Notes on The Little Learner: Parameters, Tensors, and Mathematical Operations]() Original publisher: [Read original article]() Author: James Long Published: 2024-09-02T12:00:00Z Content type: tutorial Language: en Sources: [James Long]() Topics: [dataset](), [math](), [implementation](), [render]() Tags: [dataset](), [graph](), [implementation](), [learnings](), [math](), [render]() ### AI overview Notes working through The Little Learner explain function parameters, datasets, scalars, tensors and tensor rank, then implement extended mathematical operators such as addition and sum. ### Source excerpt (note: skipping interactive content block) ^f3bf01 ^aeae51 A collection of notes as I work through The Little Learner. (note: skipping interactive content block) ^0c0c15 Chapter 1 1.5: graph a line with $w$ and $b$ parameters const f = (w, b) => x => w * x + b; render(graph(f(100, 10))); render(graph(f(10, 0))); ^2b4784 1.14: reverse the order to make $x$ an argument and $w$ and $p$ parameters // A version where w and b become parameters _after_ `x` const f = x => (w, b) => w * x + b; return graph(x => f(x)(2, 20)); ^14f8ec x is the argument of the line, while w and b which come after are parameters 1.19 plot the xs, ys dataset const xs = [2, 1, 4, 3]; const ys = [1.8, 1.2, 4.2, 3.3]; return graph({ marks: Plot.dot(zip(xs, ys), { x: n => n[0], y: n => n[1], fill: "black" }), domainX: [0, 5], domainY: [0, 5] }); ^dc0f98 Rule of parameters: every parameter is a number Given x and y, or arguments to a function, we can walk backwards and figure out the parameters and then use that to predict other y values for a given x θ is the parameter set (lowercase theta) Given θ, there parameters if it referred to as θ$_1$, θ$_2$, etc const f = θ => (θ_1, θ_2) => θ_1 * x + θ_2 ^7052b4 Chapter 2 "Scalars" are real numbers A "tensor" is a vector of scalars: [2.0, 1.0, 4.3, 4.2] The book uses tensor$^1$ with a superscript Tensors can be nested, and the superscript indicates the level of "nested" "elements" are the individual values in the tensor I think tensor$^1$ (with the 1 superscript) specifically means a vector of scalars, and higher tensors have tensors as elements All tensors$^m$ must have the same number of elements A scalar is atensor$^0$ 9 is tensor$^0$ [9, 9, 9] is tensor$^1$ [[9, 9, 9] [9, 9, 9]] is tensor$^2$ 2.25: define a function that finds the rank of a tensor window.scalarp = v => typeof v === "number"; window.rank = t => (scalarp(t) ? 0 : 1 + rank(t[0])); return log(output => { output(rank(4), 0); output(rank([4, 1]), 1); output(rank([[4, 1], [3, 6]]), 2); output(r ## Introducing native E2E testing: Learnings from the Senior Engineering Program for Women DevFeed: [Introducing native E2E testing: Learnings from the Senior Engineering Program for Women]() Original publisher: [Read original article]() Author: Joana Melo Published: 2023-09-08T12:35:44Z Content type: article Language: en Sources: [Klarna Engineering]() Topics: [Testing](), [App](), [Development]() Tags: [appium](), [automated](), [diversity](), [e2e-testing](), [engineering](), [gender](), [gender-equality](), [klarna](), [learnings](), [professional-development](), [regression](), [testing](), [typescript]() ### AI overview The author describes introducing native end-to-end testing in mini versions of the Klarna app to enable automated feature regression tests in development pipelines. The article also reflects on the Senior Engineering Program for Women, including its focus on professional growth, coaching, collaboration, technology, influence, and diversity. ### Source excerpt I made company-wide impact by successfully delivering the introduction of native end-to-end (E2E) testing in mini versions of the Klarna app. The goal was to have automated feature regression tests in our pipelines. I developed this as part of a program for senior engineering women, and today, I want to share the insights and learnings I gained from this experience. Creating fair and equal opportunities for women How do we offer women equal and fair opportunities in an industry dominated by men? Well, there are many ways to work on this topic. One that piqued my curiosity was Klarna's Senior Engineering Program for Women (SEPW). As you might wonder as well, my initial thoughts on it as with any other initiatives like this came with a lot of reservations: Is this fair? Is this the best way for me to ensure that I'm being fairly evaluated? Will it look like I am being brought to a speedlane towards an easy promotion if I happen to get one because I'm a woman? Are we going to get treated like tokens? Is this all just a marketing strategy to promote? Am I being part of and legitimizing something that has no real content and value for my career or other women? What will everyone think? When we are faced to join initiatives related to gender gap improvements, we might fall into the trap of having all the perfect and right answers before we take risks, or we can accept that there will never be the perfectly carved, impactful and life-changing solution at our doorstep. We can only experiment and learn from the results to make better decisions as we help evolving into a hopefully more gender-fair world. As a woman in engineering, I understand the issues, but I don't claim to have all the answers. And that's ok. The program The SEPW is a way for Klarna to acknowledge and accelerate the professional development of promising engineers and promote diversity within engineering. The 6 month program is designed with the individual's growth as the main focus, and based on four theme ## Learnings From Creating a Guest Book App DevFeed: [Learnings From Creating a Guest Book App]() Original publisher: [Read original article]() Author: Eevis Panula Published: 2025-06-11T04:30:21.524000Z Content type: article Language: en Sources: [Eevis Blog]() Topics: [web applications](), [Amazon S3](), [App](), [TypeScript](), [Usability](), [Content Management System](), [GraphQL]() Tags: [app](), [aws](), [aws-s3](), [blog-post](), [cms](), [graphql](), [learnings](), [typescript](), [web]() ### AI overview The article describes building a simple guest book web app for a one-night party, designed to let users submit photos, names, and messages without downloading an app or creating an account. It outlines the app structure and the use of NextJS, TypeScript, GraphQL, GraphCMS, and AWS S3, then introduces lessons from the implementation, including difficulties uploading photos to S3. ### Source excerpt So it seems my sister is currently my biggest muse for side projects. She was the reason I created Neule.art, from which you can read more in the blog post "How I created Neule.art". A while back, she asked me if I could create a guest book app for a party they had with their friends. The idea was simple - there should be a possibility to add a photo, some text, and the name(s) of the sender(s). They tried to search for a readymade app, but every one of them had some problems. I also know, from experience, that these kinds of apps can be... how to put this... Not so good usability-wise. For example, no one wants to download an app for one night to be able to take one or two pictures. No one wants to create an account for that one night (and then forget that they have it). So I wanted to try out if I could build a simple enough, non-account-needing web app. In this blog post, I won't share the code for that app. It was a bit hacky, as the app needed to work only for that one night. Aaand I was a bit in a hurry. However, I will share some learnings from creating that app. Let's first have a look at what the app was like. The Guest Book App The guest book app consisted of two pages: Login, which had this one input field for writing the password, and a page for guest book entries. In addition, there was a modal for adding a new entry. That had a form with the possibility of taking a photo (a file-type input field with accept="image/*" to open the camera) and adding names and a message. As for the tech stack, I used NextJS with TypeScript, GraphQL, and GraphCMS (at the time, they changed their name just after I finished the project to Hygraph) for CMS. As for the photos, I stored them in an AWS S3 bucket and their URL to the CMS. I've worked with all the other technologies before, but AWS was something new. However, I was pretty sure that because it's a fairly common use case to store things in AWS S3 buckets, and as React is so popular, there must be an easy solution fo ## Being on-call as a software engineer - a challenging and fast learning experience DevFeed: [Being on-call as a software engineer - a challenging and fast learning experience]() Original publisher: [Read original article]() Author: Stefan Nothaas Java Software; Backend Engineer Published: 2022-01-12T00:00:00Z Content type: article Language: en Sources: [Trivago]() Topics: [backends](), [Software](), [Development](), [Google Cloud Platform (GCP)](), [Kafka](), [Kubernetes](), [systems](), [Command-line interface]() Tags: [backends](), [blog-post](), [development](), [devops](), [engineering](), [engineering-culture](), [experience](), [google-cloud](), [infrastructure](), [kafka](), [kubernetes](), [learning](), [learnings](), [managed-services](), [mistakes](), [on-call](), [professional-development](), [root-cause-analysis](), [software](), [software-engineer](), [systems](), [tooling]() ### AI overview A trivago interview with backend engineer Stefan Nothaas examines his experience being on-call. It explains how on-call engineers respond to incidents, coordinate follow-up and root-cause analysis, and learn about infrastructure including Google Cloud, Kubernetes, Kafka and CLI tooling. ### Source excerpt At trivago, we run webservices with complex backends in different regions around the globe 24/7. Our system is being iterated and developed on a daily basis. Naturally, mistakes will be made and... ## Kotlin Mumbai: Dissecting Coroutines DevFeed: [Kotlin Mumbai: Dissecting Coroutines]() Original publisher: [Read original article]() Author: Siddhesh Patil Published: 2020-11-28T09:48:16Z Content type: article Language: en Sources: [Sid Patil - Android Engineer and Kotlin Advocate]() Topics: [Coroutines](), [Kotlin](), [Library](), [selectors]() Tags: [best-android-developer-groups-in-india](), [coroutines](), [developer](), [developer-communities-in-mumbai](), [event](), [flow](), [google-developer-experts](), [kotlin](), [kotlin-mumbai](), [kotlin-user-group-mumbai](), [kug](), [learnings](), [mohit-sarveiya](), [mohit-sarveiya-gde-for-kotlin](), [q-a](), [selectors](), [talk](), [using-cooroutines-in-kotlin]() ### AI overview An overview of a Kotlin Mumbai talk on Kotlin coroutines, covering how coroutines work, the coroutines library, Flows, Channels, shared state, selectors, and actors, followed by a question-and-answer session. ### Source excerpt Mohit Sarveiya walks us through using coroutines in Kotlin and how they work under the hood. In this talk, we will explore basic to advanced features provided by the coroutines library. ## Startup Learnings - What Taylor Williams Taught Me DevFeed: [Startup Learnings - What Taylor Williams Taught Me]() Original publisher: [Read original article]() Author: Fuzzygroup Published: 2019-12-04T00:00:00Z Content type: opinion Language: en Sources: [Scott Johnson]() Topics: [Development](), [Git](), [pull-requests](), [Software Engineering](), [Refactoring](), [Ansible](), [Deployment](), [Back end](), [Software as a service](), [Amazon Web Services]() Tags: [ansible](), [aws](), [back-end](), [deployment](), [development](), [engineering](), [git](), [learnings](), [pull-requests](), [refactor](), [repo](), [saas](), [startup](), [taylor-williams]() ### AI overview The author explains how Taylor Williams taught them disciplined Git workflows for startup and side-project development. The approach uses ticket-linked feature branches, atomic changes, pull requests, testing before merging into develop, and a pristine master branch that can be deployed at any time. ### Source excerpt Note: Code Cat watches disapprovingly as I work ... The bulk of my career has been spent at the small scale of the startup universe - companies with 15 people or less; often a lot less; more than a few times, I've been the only engineer. I have done three stints with companies at or near the three figure number of employees: Dataware, Mascot Network and Seas Education. One of the characteristics of working at the small scale of startups is that what matters is results. How you do it generally doesn't matter - that you do it does matter. And, perhaps unsurprisingly, this can lead to some bad things when it comes to engineering processes. To this point, I've actually been dubbed "the anti process" in at least one organization I spent some time at. So keep that in mind as you read on ... I'm actively working on an (unlaunched) side project and I noticed this today: That's from the repo on my side project and it indicates that I've created 500 pull requests (this was tied to issue #444 which only got merged this morning; the current issue number is 501. Issue 444 was a major refactor that has been a long coming. I'd like to joke that aggressively using pull requests, even on an unlaunched, personal side project, is "how Mother Johnson taught me to do open source" but that would be an untruth. This is a Startup Learnings post and I learned this from Taylor Williams. Taylor Williams is currently the head of software engineering for Seas Education, a SAAS product focused on record keeping for special education. I worked for Seas for about 18 months during which time I focused on AWS infrastructure, deployment, Ansible and back end features. When I came into Seas, Taylor was still a bit on the junior side but I watched him grow and develop as he took on a larger and larger role, culminating in a promotion where he took on leadership of all software engineering, across all product lines. What Taylor taught me was git discipline, specifically: All development is done in feature b ## Practical Advice for Preparing and Submitting Conference Talks DevFeed: [Practical Advice for Preparing and Submitting Conference Talks]() Original publisher: [Read original article]() Author: Map Published: 2012-06-19T20:55:56Z Content type: tutorial Language: en Sources: [Craig Kerstiens]() Topics: [Django](), [Python]() Tags: [conference](), [conferences](), [django](), [hacks](), [learnings](), [python](), [talks]() ### AI overview The article offers practical advice for preparing and submitting conference talks, including starting with small practice opportunities and refining both the talk and its proposal. It uses Jacob Kaplan Moss's DjangoCon EU keynote as an example of testing a talk format among a familiar community. ### Source excerpt A few weeks ago I was sitting at the hotel in Zurich with Jacob Kaplan Moss prior to DjangoCon EU enjoying a beer, talking about Django, and discussing a bit about our upcoming talks for the conference. He talked briefly about his upcoming keynote and how he was doing something different, including essentially 5 mini-talks. This seemed interesting enough, but the part that surprised me was when Jacob said, "I'm among friends here so it'll be a good place to test this format." Many if not all in the community know who Jacob is as one of the creators of Django, though still to be "among friends" at a roughly 300 person conference surprised me. However, as someone thats keynoted several times, spoken at conferences for many years, and familiar with many people in the community; for the 150-200 people there he had not met before, he was still truly among friends. While giving a keynote is never an easy feat, it seems to ease the worry ahead of time of doing such. Saturday night there was a bit of conversation on twitter that had some related discussion. In the last minute rush for DjangoCon US talk submissions a few that have been involved in the community for some time discussed submitting their first talk proposals. In parallel to that was some discussion around diversity, I volunteered the idea of not including presenters name's in the list when reviewing and voting on talks. While both of the above are controversial topics alone, I hope that can be left to another later time. The key idea that emerged that can be helpful to anyone looking to submit a talk to a conference is how the "pro's do it", as Jeremy Dunck put it. So without further adieu, hopefully without speaking too much for him here's likely why Jacob viewed his 300 person keynote as being among friends: 1. Start small Whether its practicing the talk itself or writing the abstract for a proposal practicing each step lets you refine this well ahead of time. In my experience, providing a talk description fo