10 Tips for Building Resilient Payment Systems

The top 10 tips and tricks for building resilient payment systems from a Staff Developer working on Shopify’s payment infrastructure.

Shopify logo
Shopify
•
Bart de Water
•14 min read•intermediate•
--
•View Original
Circuit BreakerGolangGraphQLgRPCJSONMySQLRailsRedisRubySQL

Overview

This article provides ten essential tips for building resilient payment systems, drawing from the author's extensive experience at Shopify. It covers critical strategies such as managing timeouts, implementing circuit breakers, understanding system capacity, and enhancing monitoring and logging practices.

What You'll Learn

1

How to set low timeouts in your payment system to improve user experience

2

Why circuit breakers are essential for maintaining system reliability during service outages

3

How to implement structured logging for better debugging and monitoring

4

When to use idempotency keys to prevent double charges in payment processing

5

How to conduct effective incident retrospectives to improve system resilience

Prerequisites & Requirements

  • Basic understanding of payment processing systems
  • Familiarity with monitoring and logging tools(optional)

Key Questions Answered

How can I effectively manage timeouts in payment systems?
Managing timeouts involves setting lower limits on connection, write, and read times to enhance user experience. For instance, an open timeout of one second and a write/read timeout of five seconds can significantly improve responsiveness, preventing users from waiting too long for actions to complete.
What is the purpose of using circuit breakers in payment systems?
Circuit breakers prevent unnecessary resource usage by stopping requests to services that are likely down. By implementing a circuit breaker like Semian, systems can quickly respond to failures without waiting for timeouts, thus maintaining overall system performance and reliability.
What metrics should I monitor in a payment system?
Key metrics to monitor include latency, traffic, errors, and saturation. These metrics help identify potential overload situations and ensure that the system remains responsive and reliable under varying loads, allowing for proactive management of resources.
How do idempotency keys prevent double charges in payment processing?
Idempotency keys ensure that a payment request is processed only once, even if the request is retried due to network issues. By tracking requests with unique keys, the system can avoid duplicate charges, thus protecting both merchants and customers from errors.

Technologies & Tools

Some links below are affiliate links. We may earn a commission if you make a purchase.

Backend
Ruby
Used for building payment processing infrastructure and implementing features like circuit breakers.
Database
Mysql
Utilized for managing payment data and implementing query timeouts.
Backend
Redis
Used for caching and improving performance in payment processing.
Backend
Grpc
Employed for service communication within the payment infrastructure.
Identifier
Ulid
Recommended for generating unique idempotency keys due to its sortable nature.

Key Actionable Insights

1
Implementing lower timeouts can drastically improve user experience in payment systems.
By setting timeouts to one second for opening connections and five seconds for read/write operations, you can significantly reduce waiting times, making your application feel more responsive to users.
2
Utilizing circuit breakers like Semian can enhance system resilience.
By quickly stopping requests to failing services, you conserve resources and maintain system performance, which is crucial during high-traffic events.
3
Structured logging is essential for effective debugging in distributed systems.
By adopting a machine-readable format for logs, you can easily aggregate and search logs across multiple services, which is vital for troubleshooting issues in complex payment systems.
4
Regular load testing can help identify system limits before they become issues.
Simulating high traffic scenarios allows you to understand how your payment system behaves under stress, ensuring that you can handle peak loads without service degradation.

Common Pitfalls

1
Failing to set appropriate timeouts can lead to resource exhaustion.
Without proper timeouts, unresponsive services can tie up system resources indefinitely, leading to increased costs and degraded performance.
2
Misconfiguring circuit breakers can result in wasted resources.
If circuit breakers are not tuned correctly, they may either trip too often or not at all, leading to either unnecessary service disruptions or resource wastage.

Related Concepts

Distributed Systems
Load Balancing Techniques
Incident Management Best Practices