Best Practices for Go Code Review

Code review is one of those things we all agree is important, but our execution is often… messy. It can easily devolve into nitpicking, long-winded debates about style, or worse, a rubber-stamping exercise where real issues slip through. To better navigate these challenges and avoid common pitfalls, refer to resources on The Most Common Code Review Mistakes and How to Avoid Them. For a language like Go, with its strong opinions on simplicity and concurrency, an effective Golang code review process isn’t just a nice-to-have; it’s a critical lever for building stable, maintainable systems.

If you’re building production-grade REST APIs, gRPC services, or any kind of concurrent system in Go, your code review process is your first and best line of defense. It’s not just about catching bugs. It’s about building a shared understanding of the codebase and leveling up the entire team. Beyond manual reviews, remember that automated tools like SAST tools for code security can further enhance your defenses. Let’s dig into what a truly effective review looks like.

Why Bother? The Real ROI of Code Review

Before we get into the nitty-gritty, let’s be clear on the “why.” Slowing down to review code feels counterintuitive when deadlines are looming, but the investment pays dividends.

Catching bugs early: This one’s obvious. A second pair of eyes can spot a potential nil pointer dereference, an off-by-one error, or a race condition that the author missed. Finding it in a PR is infinitely cheaper than finding it in production.

Knowledge sharing: A PR is a story about a change. The reviewer learns about a part of the system they might not know, and the author might learn a new pattern or library function from the feedback. This is how you break down knowledge silos.

Enforcing consistency: Is error handling consistent? Is logging structured the same way across the service? Code review is where you enforce these standards, making the codebase feel like it was written by a single, cohesive team, not a dozen individuals. The Impact of Lack of Coding Standard on Code Review is significant, highlighting the importance of this step.

Improving maintainability: A reviewer’s fresh perspective is invaluable. They can ask the simple question: “Will I understand this in six months?” This pushes authors to write clearer, more self-documenting code.

The Core of the Review: What to Actually Look For

Okay, so you’re staring at a pull request. Where do you focus your energy? It’s easy to get lost in the weeds. I’ve found it helps to organize my thinking around a few key areas.

Is It Idiomatic Go?

Go has a distinct style. Code that fights the grain is harder to read and maintain for anyone familiar with the language. This isn’t just about aesthetics; it’s about leveraging the language’s strengths.

Formatting and Linting: This should be a non-issue. go fmt is non-negotiable. Use a tool like golangci-lint in your CI pipeline to automate checks for common issues. This frees up human reviewers to focus on logic, not curly brace placement.

Error Handling: This is a big one. Are errors being checked or just ignored with _? When an error is returned up the stack, is it being wrapped with fmt.Errorf and the %w verb to preserve context? Are we using errors.Is and errors.As correctly instead of string comparison on error messages?

Interfaces: Go’s interfaces are powerful. Look for the “accept interfaces, return structs” principle. It makes code much easier to test and mock. Are interfaces small and focused on behavior (e.g., io.Reader), or are they giant monoliths?

Concurrency: This is where subtle, nasty bugs hide. Are goroutines being launched without a clear plan for when they’ll terminate? Is there a potential for a goroutine leak? Is a sync.Mutex being used correctly to protect shared state, or should a channel be used instead? Always run tests with the -race flag.

Standard Library: Is the author reinventing something that already exists and is heavily optimized in the standard library? (Think parsing, encoding/json, or crypto). A quick check can save a lot of code and potential bugs.

Performance and Resource Usage

For services handling real traffic, performance isn’t an afterthought. You don’t need to prematurely optimize everything, but you should be on the lookout for obvious anti-patterns.

Allocations: Is code creating a lot of garbage in a hot path? For example, appending to a slice in a tight loop without pre-allocating capacity using make([]T, 0, capacity).

Goroutine Leaks: I’m mentioning this again because it’s both a correctness and a performance issue. A leaky goroutine is a memory leak. If a goroutine is waiting on a channel that will never be written to, it will sit there forever.

Context Propagation: In services like APIs or gRPC servers, is the context.Context being passed down correctly through the call stack? This is crucial for handling deadlines, timeouts, and cancellations gracefully, preventing your service from doing useless work.

The Human Side: How to Give (and Get) Good Feedback

The hardest part of code review has nothing to do with code. It’s about people. A bad review culture can create resentment and slow everyone down. A good one fosters collaboration and growth.

The goal is a conversation, not a judgment.

For the Reviewer:

Start with the “why.” Before suggesting a change, understand the author’s intent. Ask questions: “What was the thinking behind this approach?” or “Have you considered what happens if this function returns an error?”

Provide actionable feedback. “This is confusing” isn’t helpful. “This function name is a bit ambiguous; could we rename it to FetchUserByID to be more specific?” is much better.

Batch your comments. Don’t trickle in feedback over hours. Do a full pass and submit your review so the author can address everything at once.

Automate the nits. If you find yourself repeatedly commenting on style, formatting, or simple mistakes, that’s a sign you need a better linter configuration. Your time is more valuable than a machine’s.

Praise in public. If you see a clever solution or a really clean implementation, say so! Positive feedback is just as important as constructive criticism.

For the Author:

Keep PRs small. This is the golden rule. A 100-line PR is a pleasure to review. A 2000-line PR is a nightmare that will almost certainly be rubber-stamped. Aim for small, logical, atomic changes.

Write a good description. Provide context. What problem does this solve? Why was this approach chosen? Link to the ticket or issue. A good description is an act of empathy for your reviewer.

Don’t take it personally. Feedback on your code is not feedback on you as a person. Assume good intent from the reviewer and engage with the substance of their comments.

Guide the reviewer. If there’s a specific area you’re unsure about or want a second opinion on, call it out in the PR description.

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Golang Code Review Checklist

Here’s a practical, no-fluff checklist to run through on your next review. You don’t have to check every single box every time, but it’s a great starting point for building good habits.

📦 Structure & Readability

• Is the code easy to understand? Could a new team member follow it quickly?
• Are function, variable, and package names clear and descriptive?
• Are functions small and focused on a single responsibility?
• Does the code follow the principle “accept interfaces, return structs”?
• Is the package structure logical, with no circular dependencies?
• Is the public (exported) API clear? Is anything exported that shouldn’t be?

⚡ Concurrency & Goroutines

• Does every goroutine have a clear plan for how and when it will end?
• Is there any risk of goroutine leaks (blocked forever on a channel or select)?
• Is shared memory properly protected (sync.Mutex or sync.RWMutex)?
• Are channels used for communication, not as generic data structures?
• Is context passed correctly to handle cancellations and timeouts?
• Were tests run with -race to detect race conditions?

⚠️ Error Handling

• Is every error checked, or explicitly ignored with a clear justification (// nolint or comment)?
• When propagating errors, do we use fmt.Errorf(... %w ...) to preserve context?
• Are sentinel errors (e.g., sql.ErrNoRows) handled with errors.Is or errors.As?
• Do error messages provide enough context for debugging without leaking sensitive data?

🧪 Testing

• Is there sufficient test coverage for the new logic?
• Are edge cases covered (empty values, nulls, expected errors)?
• Are tests easy to read and maintain (prefer table-driven tests)?
• Is there a benchmark for performance‑critical code?

🚀 Performance

• Are there any unnecessary allocations in hot loops (e.g., append without preallocated make)?
• Are defer statements used inside loops where they could accumulate?
• Are there any obvious N+1 query patterns when interacting with the database?

🔒 Security

• Are all external inputs properly validated and sanitized?
• Do SQL queries use parameterized statements to prevent injection?
• Are sensitive values (passwords, tokens, keys) never logged?
• Are comparisons for sensitive values (tokens, signatures) done in constant time?

Ultimately, a strong Golang code review culture is about building a feedback loop. It’s a continuous process of learning and improvement, both for the code and for the team. It takes effort to move beyond simple bug hunting, but the payoff—a more resilient, maintainable, and well-understood system—is more than worth it.