---
title: "Introducing the Merge Queue"
description: "Shopify describes a merge queue added to Shipit to reduce failures in its large monolithic Rails application, where growing pull request volume made manually checking whether master was safe unsustainable. The queue adds pull requests from GitHub, merges them when master is healthy, waits for required CI statuses, and can reject stale branches using configurable divergence thresholds. It is encouraged rather than enforced, while changing the browser extension’s visual emphasis helped make queued merging the default workflow; over 90% of core application pull requests use it. Shipit also handles unsafe deployment commits by allowing explicit marking and automatically detecting reverts of undeployed commits, marking the original and intermediate commits unsafe. These changes let deployment continue safely around reverted work without requiring developers to manually unlock the pipeline."
---

# Introducing the Merge Queue

[Shopify](https://yomu.fyi/company/shopify) · Darren Worrall · Jun 8, 2018

**Type:** Announcement

## Summary

Shopify describes a merge queue added to Shipit to reduce failures in its large monolithic Rails application, where growing pull request volume made manually checking whether master was safe unsustainable. The queue adds pull requests from GitHub, merges them when master is healthy, waits for required CI statuses, and can reject stale branches using configurable divergence thresholds. It is encouraged rather than enforced, while changing the browser extension’s visual emphasis helped make queued merging the default workflow; over 90% of core application pull requests use it. Shipit also handles unsafe deployment commits by allowing explicit marking and automatically detecting reverts of undeployed commits, marking the original and intermediate commits unsafe. These changes let deployment continue safely around reverted work without requiring developers to manually unlock the pipeline.

## Context

Shopify’s trunk-based workflow produced an increasing number of merge failures as developer and pull request volume grew. Shipit already tracked the state of master and deployments, including conditions under which further merges should pause, making it the location for merge automation.

## Approach / What changed

Shipit added queueing through its GitHub integration and browser extension, waits for pending CI, applies configurable branch-divergence limits, and permits developers to bypass the queue. It also supports manually marking commits unsafe for deployment and automatically detects reverts of undeployed commits, marking the reverted and intermediate commits unsafe.

## Takeaways

- The merge queue waits for pending CI and merges or rejects a queued pull request instead of ejecting it and requiring manual re-enqueueing.
- Configurable thresholds let Shipit reject pull requests whose branches have diverged too far by age or commit count.
- When Shipit detects a revert of an undeployed commit, it marks the original commit and intermediate commits unsafe for deployment.

## FAQ

### What happens when a queued pull request is still waiting for CI?

Shipit keeps the pull request in the queue while CI is pending. It merges it if CI passes or rejects it if CI fails, allowing developers to queue and move on.

### Can developers still merge directly to master?

Yes. The merge queue is highly encouraged but not enforced, and Shopify allows developers to override the automation when they believe it is required.

### How does Shipit handle a reverted commit that has not deployed yet?

Shipit detects the revert and marks the original undeployed commit unsafe for deployment, along with intermediate commits between it and the revert. This lets the deployment pipeline continue without manually configuring each unsafe commit.

**Tags:** [CI/CD](https://yomu.fyi/topic/ci-cd), [Deployment](https://yomu.fyi/topic/deployment), [Ruby on Rails](https://yomu.fyi/topic/ruby-on-rails)

- Source: [Shopify](https://shopify.engineering/introducing-the-merge-queue)
- Source URL: https://shopify.engineering/introducing-the-merge-queue
- Ingested by Yomu: 2026-09-17T14:12:58.891Z

[Read original post](https://shopify.engineering/introducing-the-merge-queue)