Databases (3): Transactions and Concurrency — ACID, Isolation Levels, and Locking

Sun, 21 Apr 2024 09:00:00 +0000

Every application that handles money, inventory, or any state that matters eventually hits a concurrency bug. Two users buy the last item in stock. A bank transfer debits one account but crashes before crediting the other. A report reads half-updated data and produces nonsense numbers. Transactions exist to prevent these failures, and understanding how they work is non-negotiable for anyone building production systems.

What Is a Transaction?#

A transaction is a group of operations that the database treats as a single unit. Either all operations succeed, or none of them do.

Python Engineering (6): Concurrency — Threads, Processes, and asyncio

Thu, 21 Apr 2022 09:00:00 +0000

Your script downloads 100 files one at a time. Each download takes 2 seconds, mostly waiting for the server to respond. Total time: 200 seconds. Your CPU is idle for 99% of that time, wasting compute and money on network latency. Concurrency can fix this.

Python has three concurrency models, each designed for different problems. Choosing the wrong one can make your code slow or full of race conditions. This article explains when to use each.

Concurrency on Chen Kai Blog

Databases (3): Transactions and Concurrency — ACID, Isolation Levels, and Locking

What Is a Transaction?#

Python Engineering (6): Concurrency — Threads, Processes, and asyncio