The conc repository is a Go package developed by Sourcegraph that provides structured concurrency primitives designed to make concurrent programming safer and more readable. The package addresses three core pain points in Go's concurrency model: goroutine leaks, unhandled panics in concurrent code, and the verbosity of writing correct concurrent patterns.
The package offers multiple abstractions for different concurrency scenarios. At the foundation is conc.WaitGroup, a safer alternative to the standard library's sync.WaitGroup. For bounded concurrency, the package provides pool.Pool for running tasks with a maximum goroutine limit, and pool.ResultPool for collecting results from concurrent tasks. Additional pool variants include ErrorPool for handling fallible tasks, ContextPool for canceling tasks on failure, and combinations like ResultErrorPool and ResultContextPool. For stream processing, stream.Stream enables parallel processing of ordered task sequences while maintaining serial callbacks. The iter package provides convenience functions like iter.Map and iter.ForEach for concurrent operations over slices. The panics.Catcher utility allows developers to safely catch panics spawned in goroutines.
The design philosophy centers on scoped concurrency, where all goroutines must have an explicit owner responsible for ensuring proper cleanup. This prevents the common pattern of fire-and-forget goroutines that leak resources. When goroutines panic, the Wait method will propagate the panic to the caller with decorated stack traces from child goroutines, ensuring panic information is not lost. This approach eliminates the need for developers to manually implement panic recovery boilerplate in every concurrent operation.
The package is written in Go and is classified across multiple development tool categories including source code search, code intelligence, semantic analysis, and developer productivity tools. According to GitGenius activity tracking, the repository shows a median issue and pull request response latency of 24.5 hours across 17 tracked items, with a mean latency of 2056.5 hours. The most active contributors tracked include camdencheek with 8 events, followed by gaby and sam-ulrich1 with 3 events each. The repository shares overlapping contributors with spinnaker/spinnaker, getify/you-dont-know-js, and bregman-arie/devops-exercises.
The package documentation emphasizes reducing boilerplate through high-level abstractions. Rather than manually managing goroutines with sync.WaitGroup and error channels, developers can use pool.New to create a bounded task runner or iter.Map for concurrent slice operations. Configuration methods like WithMaxGoroutines, WithErrors, WithContext, WithFirstError, and WithCollectErrored allow fine-grained control over pool behavior. The repository includes extensive examples comparing stdlib approaches with conc equivalents, demonstrating significant reductions in code complexity for common patterns like spawning goroutines, processing streams, iterating slices, and maintaining order in concurrent operations.
At the time of the README documentation, the package was in pre-1.0 status with a targeted 1.0 release for March 2023, indicating the API was still stabilizing. The project is backed by Sourcegraph's development infrastructure and is positioned as a practical toolkit for developers seeking to write safer, more maintainable concurrent Go code.
