Context and Problem
In systems that handle multiple tasks or messages, some tasks need to be processed before others based on urgency or importance.
- Task prioritization challenges.
- Inefficient processing where all tasks are treated equally.
- Delay in critical task execution due to the lack of prioritization.
- Increased complexity in managing task order.
Solution
The Priority Queue pattern ensures that tasks are handled based on their priority level, improving responsiveness and efficiency.
- Assign priority levels to tasks or messages.
- Implement a queue that processes tasks in descending order of priority.
- Ensure low-priority tasks don’t block higher-priority ones.
- Manage resource allocation to process high-priority tasks promptly.
- Monitor queue health and adjust priority assignment dynamically.
Benefits
- Efficient task management
- Ensures critical tasks are processed first without delay.
- Improved responsiveness
- Prioritizes urgent tasks, reducing time to complete high-impact operations.
- Simplified orchestration
- Makes it easier to manage and balance task execution.
Trade-offs
- Increased complexity
- Requires additional logic for priority handling.
- Potential starvation
- Lower-priority tasks might be delayed indefinitely if the queue is full of high-priority tasks.
- Overhead
- Managing priorities can incur extra processing cost.
Issues and Considerations
- Task starvation
- Ensure low-priority tasks are not indefinitely delayed.
- Fairness
- Maintain fairness across tasks with different priorities.
- Dynamic priority adjustment
- Implement a system for dynamically adjusting priorities based on real-time metrics.
When to Use This Pattern
- When tasks need to be executed in order of urgency or importance.
- When critical tasks must be handled immediately, even in high-load systems.
- When you need to ensure that low-priority tasks don’t block high-priority operations.