Intern Report – A survey on selection techniques of consensus participants in blockchains

Hello, I am Takahashi. I participated in the internship of the engineering on-the-job training course in 2020. I usually research algorithms and data structures at Kyoto University. During my internship, I became a member of the LINE Blockchain Lab team, where I conducted research on various blockchain technologies and proposed functional improvements based on my […]

Kafka-based job queue library ‘Decaton’ examples

Introduction: Decaton LINE recently released an in-house developed library, Decaton, as open source. Decaton is a Kafka-based asynchronous job queue library, and it is widely used throughout LINE. GitHub: line/decaton – High throughput asynchronous task processing on Apache Kafka In fact, Kafka offers Kafka Streams, its official library for processing streams. However, Kafka Streams did not […]

On code readability – 1. Introduction and principles

Presentation overview Ever since starting development for LINE beginning in 2011, we have been continuously developing and improving features to provide a better user experience. The growth of the project resulted in an increase of 1.5 million lines of Android client code including modules, and the team expanded to more than 50 members. For such […]

Performance impact of MySQL performance-schema-instruments

Hi, there! I’m Otsuka (tom__bo), mainly responsible for MySQL operations and development of various DB administration and verification tools. In this post, I am going to write about my experiment on MySQL performance when its performance consumers, namely the performance_schema database and the innodb_metrics table of the information_schema database, are up and running.  I got to learn about the performance_schema and the INFORMATION_SCHEMA.INNODB_METRICS from a book […]

How AIR ARMOR checks iOS Code Signing

AIR ARMOR is a security solution of AIR; AIR is a component of the LINE GAME PLATFORM. You can refer to Seunghoon’s posting on AIR GO and APK Signing for information on the APK signature scheme. For this posting, I’ll explain about iOS code signing, one of Apple’s security mechanism. Code signing is to verify the integrity of the software code […]

Troubleshooting Data Engineering Software

Hello, I’m Keiji Yoshida. I currently work as a data engineer at LINE Data Labs. In this posting, I’d like to share a few cases on data engineering software troubleshooting: Apache Hadoop YARN ResourceManager failover Apache Hadoop HDFS NameNode failover Apache Zeppelin Notebook scheduler issue Apache Zeppelin deadlock issue Apache Spark SQL performance issue Troubleshooting failover issue in Apache Hadoop […]


Hello, this is Seisuke. I work at LINE Fukuoka as an engineer for LINE app for Android. Our office held a hackathon for LINERs in November 2018, at which I had a chance to try out TIC-80, a fantasy console, with LIFF. I wanted to share some of the lessons I learned through the event. […]

LINE Security Bug Bounty Program Report 2018

Hello, this is Kazuhiro Kubota from the LINE Security Department. Last time we brought you the report for the first half of 2018. Today, I’d like to summarize the results of the LINE Security Bug Bounty program for 2018. Number of reports in 2018 In 2018, a total of 88 reports qualified for the program. This figure is almost twice as many […]

conflr: Publishing R Markdown documents on Confluence

I’m Hiroaki Yutani from Data Analysis team, Data Labs. Today, I’m happy to announce conflr (pronounced as confl-R), an open source R package for publishing R Markdown documents on Atlassian Confluence. In this post, I’ll briefly explain the motivation; why we need this, and how to use conflr. A gap between R Markdown and Confluence Confluence is one of […]

Introducing Rekcurd for Clova

Machine learning (ML) is getting more and more popular these days. You probably are using it already at your work, or have been encouraged to have a go at it. Thanks to its popularity, we see more tools and frameworks for machine learning emerging. Not only that, anyone can learn linear regression, logistic regression as well as various deep learning algorithms such as Perceptron, Adaboost, Random Forest, Support Vector Machine and XGBoost. Although we are seeing growth in tools and frameworks for learning, there are not enough tools or frameworks for operating machine learning modules. Which brings me to introduce a machine learning management platform, Rekcurd, we use for the LINE’s AI platform, Clova.