Competing Consumers

Kind: pattern

Layer: Execution Core

Record: architecture:competing-consumers

Severity: contextual

Scope: service, messaging, scalability

Canonical: Ontology

A design pattern in which several consumers read from one queue, and each message goes to only one of them.

Listed in Architecture principles, after Idempotent Consumer and before Defensive Programming.

Requires

• Message Queue

Reinforces

• Horizontal Scaling
• Load Balancing

Enables

• Parallel Message Processing
• Consumer Elasticity

Conflicts with

• Single Serial Consumer

In tension with

• Ordering

Tensions

• Competing Consumers / Ordering

Violated by

• Single Serial Consumer

Severity

• contextual

Category

• Event / Messaging / Asynchronous Architecture

Linked from

• Event / Messaging / Asynchronous Architecture
• Scalability / Performance / Optimization
• Event Messaging Async
• Quality Attributes
• Severity levels
• The resolutions