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CI Performance and Test Execution

4 posts · May 2022 – May 2026

What this trail covers

This feature thread tracks Stripe's continuous efforts to optimize its Continuous Integration (CI) pipeline and testing infrastructure to handle a massive, rapidly growing codebase. Initial focus was on improving test execution speed and efficiency, leading to the development of sophisticated systems like Selective Test Execution. This system allows Stripe to run only a small percentage of tests on average, significantly reducing CI times and enabling faster development cycles. This post details the technical implementation and impact of Selective Test Execution on a 50M-line Ruby monorepo, demonstrating how it reduces test execution time and improves developer productivity.

All Stripe trails
  1. Scaling up your microservice testing with Apache SparkThis post introduces the use of Apache Spark to scale microservice testing, addressing the challenge of testing services with complex input dependencies. It highlights how Spark's parallelism and scalability can be used to build regression test harnesses, enabling comparison of old and new implementations, modeling of rule changes, and impact quantification.
  2. Selective Test Execution at Stripe: Fast CI for a 50M-line Ruby monorepoThis post details the technical implementation and impact of Stripe's Selective Test Execution system on a 50M-line Ruby monorepo. It explains how the system analyzes code changes to determine which tests are relevant, allowing Stripe to run only about 5% of its tests on average. This significantly reduces CI times, enabling faster development cycles and improving developer productivity. The post highlights the trade-offs involved in achieving this level of test selection and the engineering effort required to maintain such a system at scale.
  3. Optimize payment flow while reducing code complexity with Stripe's A/B TestingThis post details how Stripe's A/B testing capabilities can be leveraged to optimize payment flows and reduce code complexity. It explains how A/B testing allows for data-driven decisions in feature rollout and iteration, contributing to faster development cycles and improved CI/CD efficiency.
  4. Fast builds, secure builds. Choose twoThis post details Stripe's approach to achieving both fast and secure builds within their CI system. It discusses the inherent trade-off between speed and security and outlines strategies for managing this balance. The post highlights the importance of a robust CI system for orchestrating build pipelines and executing numerous test suites, emphasizing the need to meet high security standards through a combination of open-source technologies and novel engineering practices. It introduces the concept of choosing two out of 'fast builds', 'secure builds', and 'comprehensive test coverage', and explains how Stripe navigates these choices.