Parallel Sub-Workflow Execution with Wait-for-All Synchronization in n8n

Overview

This workflow demonstrates a robust pattern for executing multiple sub-workflows in parallel and synchronizing their completion before continuing. It is designed in n8n and leverages batch processing, webhooks, and conditional logic to manage parallel tasks efficiently.

Key Features

• Parallel Processing: Uses the splitInBatches node to divide items for concurrent sub-workflow execution.
• Webhook Integration: Initiates sub-workflows via webhooks and waits for their callback responses.
• Completion Tracking: Employs custom code nodes to track finished sub-workflows using a finishedSet variable.
• Synchronization: Utilizes a wait-and-check loop to ensure all parallel tasks are completed before proceeding.
• Manual Trigger: Allows for easy testing and manual initiation of the workflow.

Benefits

• Efficiency: Reduces total processing time by running tasks in parallel.
• Reliability: Ensures no step is skipped by waiting for all sub-workflows to finish.
• Scalability: Easily adapts to varying numbers of parallel tasks.
• Automation: Minimizes manual oversight and intervention.

Use Cases

• Batch processing of data with external APIs.
• Coordinating multi-step approval processes.
• Synchronizing updates across multiple systems.

Integrations & Processes

Key integrations include webhooks for sub-workflow initiation and callback, HTTP requests for external communication, and custom code for logic and tracking. This pattern is ideal for complex automation scenarios requiring parallel execution and synchronization.