The Hidden Cost Of GraphQL And NodeJS

Summary

The video script discusses the performance and scaling tradeoffs of using Node.js and GraphQL in web application development. It highlights that while these technologies are popular, they can introduce latency and performance issues due to the heavy use of promises and the non-blocking I/O nature of JavaScript. The speaker suggests that sometimes reverting to callbacks or a more synchronous approach can be beneficial. They also touch on the challenges of garbage collection and the impact of GraphQL's resolver structure on the event loop. The script concludes with a call to action for developers to be mindful of the overhead introduced by promises and to consider alternatives to GraphQL for certain use cases.

Takeaways

• 😲 Node.js and GraphQL are popular for web applications but can introduce scaling and performance tradeoffs.
• 🤔 The speaker questions the performance benefits of JavaScript over Rust due to the overhead of promises in JavaScript.
• 📈 Excessive use of promises in GraphQL can degrade per-request performance, causing latency increases.
• 🔁 JavaScript's non-blocking IO and event loop can be efficient, but only if managed well and not overwhelmed by heavy processing.
• 🚫 Overuse of async functions can lead to performance issues, as each promise adds work to the event loop.
• 🗃️ The modular design of GraphQL, while beneficial for developers, can result in 'chatty protocols' and excessive database queries.
• 📉 Benchmarks show that GraphQL's resolver structure can cause 2 to 3 times more latency compared to REST endpoints.
• 🧐 The speaker suggests that sometimes reverting to callbacks or synchronous code can improve performance over promises.
• 🗑️ Unnecessary promises can lead to increased memory usage and more frequent garbage collection, impacting performance.
• 🔍 Diagnosing performance issues involves confirming event loop blockage, promise overhead, and database query latency discrepancies.

Q & A

What are the performance tradeoffs mentioned for using Node.js and GraphQL?

The performance tradeoffs mentioned include scaling issues and potential degradation of per-request performance due to excessive promise instantiation, which can increase latency by 2 to 3 times.

What is the speaker's opinion on JavaScript's performance compared to Rust?

The speaker initially questions the claim that JavaScript can be faster than Rust, indicating some skepticism about the performance benefits of JavaScript.

Why does the speaker suggest that promises might be bad for performance in Node.js?

The speaker suggests that promises can be bad for performance because each promise adds a minuscule but non-zero amount of work for the event loop, which can lead to increased latency.

What is the role of the event loop in Node.js, and how can it affect performance?

The event loop in Node.js manages the execution of callbacks and is crucial for handling asynchronous operations. However, if the event loop is overwhelmed, it can block other requests, leading to sporadic performance issues.

What is the 'N+1 query problem' mentioned in the script, and how does it relate to GraphQL?

The 'N+1 query problem' occurs when a system makes N+1 database queries instead of the optimal number of queries, leading to performance degradation. In GraphQL, this can happen if each field in a query results in a separate database call, which is why data loaders are used to batch these requests.

What is the speaker's view on the modular design of GraphQL and its impact on performance?

The speaker views the modular design of GraphQL as beneficial for developer experience but detrimental to performance due to the promise-heavy code it generates, which can lead to increased latency.

What is the 'chatty protocol' mentioned in the script, and how does it relate to GraphQL?

A 'chatty protocol' refers to making a large number of small requests to a server, which can degrade performance. In GraphQL, this can occur when queries are broken down into many small, nested requests, each creating a promise.

What is the speaker's suggestion for improving the performance of GraphQL applications?

The speaker suggests rewriting GraphQL queries to use fewer async type resolvers, manually querying the database in a single resolver for performance-sensitive queries, and considering whether GraphQL is necessary for the application.

How does the use of async/await in JavaScript affect the event loop?

Using async/await in JavaScript can affect the event loop by creating additional promises, which can cause the execution to go to the back of the queue each time a promise resolves, potentially leading to increased latency.

What is the speaker's stance on the use of Express framework in the context of performance?

The speaker criticizes the Express framework for its performance, stating it is one of the worst frameworks ever created, particularly highlighting its inefficiency in handling requests.