Why Message Queues Are Harder Than They Look: The Hidden Complexity of "Simple" Asynchronous Communication
A financial services company migrated their payment processing to a message queue architecture. The design seemed straightforward: producers publish payment requests, workers consume and process them. Six months later, they discovered their customers had been double-charged for approximately 3% of transactions. The queue was working exactly as configured—the problem was that “working” meant something different than they expected. Message queues occupy a strange position in distributed systems. They appear deceptively simple on the surface: put message in, get message out. But beneath that simplicity lies a maze of trade-offs involving durability, ordering, delivery guarantees, and failure modes. Understanding these trade-offs isn’t academic—it’s the difference between a reliable system and one that silently corrupts data. ...