Process Manager

The Process Manager pattern provides a centralized point of control for managing and executing potentially long-running or complex tasks. It decouples the task submission from the actual task execution, allowing for features like queuing, prioritization, resource management (such as thread pools), and monitoring of process status. Instead of directly handling tasks within the application’s main thread, tasks are submitted to a manager which orchestrates their execution, often using a pool of worker threads or processes.

Usage

This pattern is widely used in scenarios requiring asynchronous task processing, background jobs, or the ability to handle a large number of concurrent requests without blocking the main application flow. Common use cases include: image or video processing, sending large-scale email campaigns, generating reports, data ingestion pipelines, and handling computationally intensive operations like machine learning model training. It’s particularly valuable in web applications where responding to user requests quickly is crucial.

Examples

• Celery (Python): Celery is a distributed task queue heavily based on the Process Manager pattern. Developers define tasks as Python functions, which are then submitted to a Celery broker (e.g., RabbitMQ or Redis). Celery workers pull tasks from the broker and execute them, providing features like task scheduling, retries, and result tracking.
• Quartz (Java): Quartz is a powerful open-source job scheduling library. It utilizes a Process Manager approach to manage scheduled jobs. Jobs are defined as Job instances and associated with Triggers, which specify when and how often the jobs should run. Quartz’s Scheduler is the process manager, responsible for maintaining a pool of threads and executing jobs according to their triggers.
• Laravel Queues (PHP): The Laravel framework’s queue system leverages the Process Manager pattern. Jobs are pushed onto queues (using drivers like Redis, Amazon SQS, or databases). Worker processes, managed by the queue:work Artisan command, retrieve jobs from the queue and process them in the background.