# The Complete Guide to Context in Golang: Efficient Concurrency Management  ## Metadata - Author: [[Jamal Kaksouri]] - Full Title: The Complete Guide to Context in Golang: Efficient Concurrency Management - Category: #articles - Summary: Concurrency management is crucial in Go programming, and the Context package in Golang helps in achieving this. Context provides a mechanism for controlling the lifecycle, cancellation, and propagation of requests across multiple goroutines. This comprehensive guide explores the purpose, usage, and best practices of context in Golang, with real-world examples. It covers topics such as creating a context, propagating context, retrieving values from context, canceling context, timeouts and deadlines, context in HTTP requests and database operations, and best practices for using context. It also discusses the role of context in microservices and web servers. - URL: https://medium.com/@jamal.kaksouri/the-complete-guide-to-context-in-golang-efficient-concurrency-management-43d722f6eaea ## Highlights - Context provides a mechanism to control the lifecycle, cancellation, and propagation of requests across multiple goroutines. ([View Highlight](https://read.readwise.io/read/01k2q7ce6x9yma3pqkxrhgwtsa)) - Context is a built-in package in the Go standard library that provides a powerful toolset for managing concurrent operations. ([View Highlight](https://read.readwise.io/read/01k2q7cq3dgb42h084c59erf0q)) - ensuring that related operations can gracefully terminate when necessary. ([View Highlight](https://read.readwise.io/read/01k2q7czcxf2t1gxnvqvfn9wvw)) - Consider a scenario where you need to fetch data from multiple APIs concurrently. By using context, you can ensure that all the API requests are canceled if any of them exceeds a specified timeout. ([View Highlight](https://read.readwise.io/read/01k2q7dbgxe2cbvwrmjm994z8x)) - Note: Q: I understand that we pass context into functions and they receive it as parameters, but how would a concurrent API request be able to detect a change in the context? So we don't check context properties in the actual code right, does Go automatically detect changes in that parameter object when the function is running? A: Go doesn't "magically" mutate a passed context; cancellation is propagated via the context's Done() channel (and ctx.Err()), so goroutines detect cancellation by selecting on <-ctx.Done() or by using library APIs that accept a context (http.NewRequestWithContext, db.QueryContext) which themselves watch Done(); WithValue returns a new context (not a mutation) and should not be used for signaling.