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Backend Software Engineering with Krishna Kumar Mahto
Backend Software Engineer, focused on Java-based backend applications, PostgreSQL in databases, Kafka/ActiveMQ/RabbitMQ in messaging.
Latest articles
If AI Writes Code, Where Do Guardrails Live - a Conjecture
Guardrails in software engineering are often misunderstood. Most engineers associate guardrails with: null checks validations defensive coding That is only a small part of the story. A more accur
Understanding Garbage Collection (GC) and Stop-The-World (STW) in the JVM
This guide explains — step by step — how the JVM’s garbage collector actually works.We’ll start from how memory is structured (Eden, Survivor, Old), move to what happens during a Minor GC, then see what Stop-The-World (STW) really means, and finally ...
Write-Ahead Logging (WAL) in PostgreSQL: How It Works
PostgreSQL guarantees durability using Write-Ahead Logging (WAL). WAL ensures that once a transaction is committed, its changes survive crashes, even if the actual table or index pages were never written to disk at the time of failure. This article g...
How PostgreSQL VACUUM Works: Dead Tuples, FSM/VM, and Locking
PostgreSQL uses MVCC (Multi-Version Concurrency Control).Each UPDATE inserts a new row version (xmin = current XID) and marks the old one dead (xmax = current XID).Each DELETE marks the row dead by setting xmax. Dead tuples remain on disk, still refe...
How PostgreSQL Decides Row Visibility with MVCC
PostgreSQL implements MVCC (Multi-Version Concurrency Control) so that transactions see a consistent view of data while minimizing blocking.This design is central to PostgreSQL’s ability to balance consistency with concurrency. Tuple metadata: xmin ...
PostgreSQL Locks — A Detailed Guide
PostgreSQL Locks — A Detailed Guide When working with PostgreSQL, understanding locks is essential for reasoning about concurrency and troubleshooting blocking queries. Postgres uses two main categories of locks: row-level locks and table-level locks...
How WhatsApp Web Gets Your Chats (and why it’s secure — mostly)
When you open WhatsApp Web and scan the QR, it looks like “all my chats just appear.” But WhatsApp does not stream your entire history from a server archive. Instead it uses a short, deliberate sequence of steps designed for three goals: Security: k...
What are Microservices - Intro
Microservices - What does it mean? Googling microservices will present you with many definitions. All of them essentially point to the same basic idea. However, we shall attempt at coming to a more holistic understanding of what the term really mean...