Message Dispatcher

Overview

Message Dispatcher coordinates multiple message processors to handle messages concurrently from a single channel, improving throughput and system responsiveness.

Problem

How can you distribute message processing across multiple threads or processes? A single-threaded message consumer may not provide adequate throughput for high-volume channels. You need to process messages concurrently while maintaining control over the number of concurrent processors.

Solution

Use a Message Dispatcher that receives messages from a channel and distributes them to multiple performer threads or processes for concurrent processing. The dispatcher manages the pool of performers, assigns messages to available performers, and coordinates their work.

Key Characteristics

• Concurrent Processing: Multiple messages processed simultaneously
• Workload Distribution: Distributes messages to performers
• Thread Pool Management: Controls number of concurrent processors
• Load Balancing: Assigns work to available performers
• Throughput Improvement: Increases message processing rate
• Resource Management: Limits concurrent resource usage

When to Use

• High message volumes require concurrent processing
• Message processing is CPU or I/O intensive
• Need to improve system throughput
• Messages can be processed independently
• Want to control concurrency levels
• Scaling message processing within a single instance
• Implementing parallel processing patterns

Implementation Considerations

• Thread Safety: Ensure thread-safe message processing
• Pool Size: Determine optimal number of performers
• Message Ordering: Concurrent processing may affect order
• Error Handling: Handle failures in performer threads
• Backpressure: Manage when performers are all busy
• Resource Limits: Prevent resource exhaustion
• Graceful Shutdown: Stop processing cleanly

Related Patterns

• Competing Consumers
• Message Channel
• Transactional Client
• Thread Pool (general pattern)