Question 1

How do I limit concurrent HTTP requests in Go using semaphore?

Accepted Answer

Create a semaphore with a limit, then acquire it in your HTTP handler with a timeout using context, as shown in the quick start example. This throttles requests to prevent server overload and handles cancellations gracefully.

Question 2

What's the difference between kamilsk/semaphore and Go's sync.WaitGroup?

Accepted Answer

Semaphore controls access to a shared resource or limits throughput with timeout support, while sync.WaitGroup is for waiting on a group of goroutines to finish. Semaphore is better for rate-limiting and deadlock prevention in concurrent operations.

Question 3

How to handle timeouts when acquiring a lock with semaphore?

Accepted Answer

Use the breaker.BreakByTimeout or breaker.BreakByContext functions provided by the library, as illustrated in the code snippets. This ensures operations don't hang indefinitely and integrates with Go's context for deadline propagation.

Question 4

Is semaphore v5 stable for production use?

Accepted Answer

Yes, v5 follows semantic versioning and is the actual development branch, but be aware of breaking changes from previous versions. Check the README for migration notes and ensure compatibility with your codebase.

Question 5

Can I execute shell commands in parallel with the included CLI tool?

Accepted Answer

Yes, the semaphore CLI tool allows adding and executing commands like docker build or ansible-playbook in parallel with controlled concurrency, as demonstrated in the console example. It's useful for automating parallel task execution.

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