Resolving Deadlocks in ESHOPMAN's Cart Completion Workflows for Custom Logic

As an e-commerce migration expert at Move My Store, we often see our ESHOPMAN clients leveraging its powerful workflow engine to build highly customized headless commerce experiences on HubSpot CMS. Extending core functionalities like cart completion is a common requirement, especially for marketplaces or unique order processing flows. However, a recent community discussion highlighted a critical challenge: a deadlock issue when trying to safely extend ESHOPMAN's completeCartWorkflow.

The Challenge: Deadlocks in Custom Cart Completion Workflows

Developers building custom business logic around ESHOPMAN's cart completion often follow the recommended pattern of wrapping the core completeCartWorkflow within their own custom workflow using .runAsStep(). This allows for pre- and post-processing steps, such as fetching related data, creating new records, or updating existing ones—a crucial capability for marketplace models managed through HubSpot.

The problem arises because both the parent custom workflow and the nested completeCartWorkflow attempt to acquire a lock on the same cart ID. ESHOPMAN's workflow documentation suggests that when a nested workflow acquires a lock, it should typically be skipped if the parent workflow already handles the locking mechanism. This prevents redundant lock attempts and potential deadlocks.

The Discrepancy: Documentation vs. Implementation

While the documentation implies nested locks should be skipped, the actual implementation of acquireLockStep within ESHOPMAN's core completeCartWorkflow does not explicitly include the skipOnSubWorkflow: true flag. This means that even when your custom parent workflow correctly acquires the cart lock, the nested completeCartWorkflow.runAsStep() will attempt to acquire the same lock, leading to a deadlock and a subsequent timeout failure after 30 seconds.

Consider the following pattern, which, despite being aligned with documented approaches for extending workflows, leads to a deadlock:

import { createWorkflow } from "@eshopman/framework/workflows-sdk";
import { acquireLockStep, completeCartWorkflow, releaseLockStep } from "@eshopman/core-flows";

// This pattern, intended for extending cart completion, results in a deadlock
const customCompleteCart = createWorkflow("custom-complete-cart", (input) => {
  acquireLockStep({ key: input.cart_id, timeout: 30, ttl: 120 }); // Parent acquires lock
  completeCartWorkflow.runAsStep({ input: { id: input.cart_id } }); // Nested workflow tries to acquire same lock
  releaseLockStep({ key: input.cart_id });
});

The result is an error indicating a failure to acquire the lock, halting the cart completion process for your ESHOPMAN storefront deployed on HubSpot CMS.

Why Workarounds Are Problematic

• Removing the Outer Lock: The most immediate "fix" might seem to be removing the lock from the parent custom workflow. However, this introduces a critical race condition. ESHOPMAN's payment processing (e.g., triggered by Stripe webhooks) often involves a separate workflow (like processPaymentWorkflow) that calls completeCartWorkflow. Without the outer lock, your storefront-triggered workflow could race with the webhook-triggered workflow for the same cart, leading to inconsistent states or data corruption.
• Using Internal Hooks: Another potential avenue, such as the orderCreated hook within the completeCartWorkflow, is marked with @ignore in its JSDoc and is not officially documented. Relying on undocumented internal hooks is not a safe or stable practice for production ESHOPMAN applications.

Expected Resolution and Best Practices for ESHOPMAN Developers

For ESHOPMAN developers building robust headless commerce solutions with Node.js/TypeScript and deploying on HubSpot CMS, a clear and safe pattern for extending cart completion is essential. The community consensus points to two primary resolutions:

• The acquireLockStep within ESHOPMAN's core completeCartWorkflow should be updated to include skipOnSubWorkflow: true. This would align its behavior with the general guidelines for nested workflows and allow the documented pattern to function as expected.
• Alternatively, ESHOPMAN's official documentation should be updated to clearly reflect the current behavior and provide an explicit, working pattern for safely extending cart completion without encountering deadlocks or race conditions.

Understanding these nuances is vital for ESHOPMAN developers to build scalable and reliable custom storefronts, ensuring seamless customer experiences and robust backend operations within the HubSpot ecosystem.