---
title: "Latest reads"
description: "The engineering internet, summarised so you can actually read it."
---

# Latest reads
> The engineering internet, summarised so you can actually read it.

## Articles

### [GrabPay Wins Best Fraud Prevention Innovation at the Florin Awards](https://yomu.fyi/post/grabpay-wins-best-fraud-prevention-innovation-at-the-florin-awards.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Foo Wui Ngiap
- Published: Oct 12, 2016

Grab won the Best Fraud Prevention Innovation (Community Votes) Award at the 2016 Florin Awards for its GrabPay platform. To support secure cashless transactions across Southeast Asia, Grab deployed a dedicated risk and fraud detection engine when launching GrabPay earlier in the year. The system utilizes machine learning algorithms that continually evolve by analyzing driver, passenger, and travel pattern data across massive transaction volumes. Furthermore, Grab provides full financial protection by covering any unauthorized fraudulent transactions for both passengers and drivers. At the time of the announcement, the platform supported up to 1.5 million daily bookings and exceeded 23 million app downloads.


### [Round-robin in Distributed Systems](https://yomu.fyi/post/round-robin-in-distributed-systems.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Gao Chao
- Published: Sep 27, 2016

Building client-side load balancing for Grab's Common Data Service prompted a move from AWS Elastic Load Balancers to DNS discovery due to persistent connection issues and unpredictable scaling events. After patching an open-source library that failed to rotate IP sequences properly, the author evaluated different Go patterns for round-robin routing. A mutex-protected array counter provides the simplest model for basic retrieval, though adding mutations requires careful lock coordination. Alternatively, a dedicated balancer goroutine receiving requests over nested channels enables explicit operation timeouts and centralized event handling at the cost of higher code complexity and channel creation overhead. The author recommends the mutex approach for resource fetching and the goroutine-based design for workload balancing.


### [Why Test the Design with Only 5 Users](https://yomu.fyi/post/why-test-the-design-with-only-5-users.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Avinash Papatla
- Published: Aug 26, 2016

Stakeholders often question whether qualitative testing with only five participants yields reliable design findings. The chosen research problem dictates the methodology, with qualitative usability evaluations requiring smaller cohorts than broad quantitative surveys. Jakob Nielsen's 1993 analysis demonstrated that testing with five participants uncovers 75 to 80 percent of usability issues, after which additional users yield diminishing returns. In agile environments, teams maximize efficiency by iterating designs across successive rounds of five participants rather than testing large cohorts simultaneously. This five-user threshold applies strictly to qualitative usability testing for specific feature flows rather than opinion gathering, A/B testing, or multi-segment user analysis.


### [Programmers Beware - UX is Not Just for Designers](https://yomu.fyi/post/programmers-beware-ux-is-not-just-for-designers.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Corey Scott
- Published: Jul 5, 2016

Software engineers frequently overlook user experience when designing APIs, SDKs, and code-level functions. Usability issues arise across various technical interfaces, from mobile apps forced to coordinate multiple round-trip network calls to ambiguous function signatures that obscure boolean arguments. To counter this, engineers can apply a five-question discovery framework to identify user identity, core objectives, user capabilities, ways to reduce user burden, and familiar paradigms. Practical remedies include sacrificing strict RESTful separation to merge mobile endpoints, placing validation logic inside internal RPC servers, and replacing boolean arguments with explicitly named helper functions. Ultimately, treating calling systems, end users, and fellow programmers as users shifts implementation complexity from consumers to servers.


### [Grab You Some Post-Mortem Reports](https://yomu.fyi/post/grab-you-some-post-mortem-reports.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Lian Yuanlin
- Published: Feb 4, 2016

Grab describes how its service-oriented architecture makes cross-team production debugging difficult because engineers may lack familiarity with other teams’ code and architecture. Post-mortem reports are presented as the glue for shared understanding, but a sample incident entry lacks service context, bug detail, impact, chronology, and investigation steps. The proposed standard has four requirements—Chronology, Context, Empowerment, and Solutions—covering timelines, service internals, blameless educational diagnosis, and remedies across People, Product, and Process. A template includes initial symptoms, a timestamped timeline, log-based investigation with code evidence, temporary and permanent fixes, and improvement actions, while peer review by another team is required before finalization.


### [The Curious Case of the Phantom Instance](https://yomu.fyi/post/the-curious-case-of-the-phantom-instance.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Lian Yuanlin
- Published: Dec 28, 2015

Datadog dashboards for the grab\_attention cluster displayed periodic 1.5X step increases in Elastic Load Balancer (ELB) health check requests and ElastiCache Redis connections, creating the illusion of an untracked instance running outside Auto Scaling Group records. Inspecting instance hostname tags revealed that the existing two instances were simply receiving elevated ping counts from the load balancers. AWS Support clarified that ELB scaling events provision new nodes while keeping old nodes running for roughly 90 minutes to handle cached DNS clients. Investigation also revealed that two separate ELBs were attached to the cluster, altering expected request baselines. Furthermore, the application's health check endpoint initiated a non-pooled Redis connection on every request, directly translating load balancer pings into database connection spikes.


[Newer posts](https://yomu.fyi/page/75.md)