pessimistic-locking

System design exercises by Arpit Bhayani

Pessimistic row-level locking and distributed advisory locks for EF Core — ForUpdate() / ForShare()

Case Study - Sample Book Delivery App (Spring Boot, Spring Security , Mysql, JUnit, Integration Test, Docker, Test Container, AOP, CI/CD, Prometheus, Grafana, Github Actions)

A basic hotel reservation system with 2PC using pessimistic and optimistic locks in Go

distributed and local lock provider

A high-performance Payment Gateway API built with Spring Boot 3 to solve concurrency race conditions and guarantee idempotency using Redis and PostgreSQL Pessimistic Locking.

In this repo I would like to show 4 strategies of concurrency control for writing data using Python SQLAlchemy ORM and PostgresSQL (however this examples could be easily transformed to plain SQL).

A basic e-commerce application is built using Go/Gin and follows micro-service architecture

Examples of applying pessimistic and optimistic concurrency control with AWS DynamoDB.

A robust Train Seat Reservation API built with .NET. Demonstrates Clean Architecture, DDD, CQRS, and pessimistic concurrency control using MS SQL Server and Redis.

A practical microservices project demonstrating the Saga Pattern for distributed money transfers using Spring Boot, Apache Kafka, PostgreSQL, Docker Compose, Transactional Outbox, Idempotency, and Pessimistic Locking. The project shows how a transfer can remain consistent across multiple services without relying on one global database transaction.

A high-reliability double-entry financial ledger microservice built with Java 25 & Spring Boot 4. Features database-level pessimistic write locking (SELECT ... FOR UPDATE), payment-grade HTTP idempotency key replay, Flyway migrations, OAuth2 JWT auth, and structured ECS logging.

A Spring Boot and React banking architecture implementing a double-entry ledger, idempotent UPI transaction processing, and deterministic pessimistic locking.

Banking Application APIs | RESTful Banking APIs built with Java & Spring Boot, using JPA, JDBC, and MySQL for persistence. Implemented pessimistic locking, DTOs with Java records, and global exception handling. Tested via Postman.

A Spring boot application, showcasing different locks that can be implemented in a Ticketmaster clone.

Spring Boot and PostgreSQL transaction backend for safe concurrent money transfers, verified with an automated, CI-enforced test.

Task

A BookMyShow-like ticket booking system with seat hold mechanism, and pessimistic locking to prevent double bookings.

Production-grade delivery integration platform. Spring Boot 3 · JWT + Refresh Token Rotation · RBAC · Idempotency · Pessimistic Locking · PostgreSQL · Docker

Pessimistic Locking example over MySQL database table row