Dispenso: high-performance concurrency, enabling highly parallel computation

Dispenso, a library developed under the Facebook Incubator program, represents a significant advancement in the field of task parallelism for C++ programming. The library is designed for efficient execution of tasks in parallel, offering a range of features that facilitate high-performance concurrency. This makes it a powerful tool for highly parallel computation.

Key Features of Dispenso:

1. Thread Pools and Task Sets: Dispenso provides mechanisms for creating and managing thread pools and sets of tasks, enabling efficient parallel execution of work.
2. Parallel Loops: It includes parallel versions of for_each and for_each_n loops, as well as a parallel_for construct for efficient iteration over ranges in parallel.
3. Futures and Pipelines: The library offers a futures implementation for asynchronous programming and facilities for parallel pipelining of workloads.
4. Concurrent Data Structures: Dispenso includes concurrent versions of common data structures, such as vectors, and provides an object arena for fast allocation of objects of the same type.

Comparison with Other Libraries:

• TBB (Threading Building Blocks): While there is significant overlap with TBB, Dispenso offers better integration with modern C++ standards and improved performance in some scenarios, especially for small and medium-sized loops.
• OpenMP: Dispenso generally outperforms OpenMP for medium and large workloads, although OpenMP has an edge in small loops due to direct compiler support.
• Folly: Another library from Meta, Folly lacks parallel loop constructs and task sets that Dispenso offers. Dispenso's futures are also faster and lighter-weight compared to Folly's for compute-bound applications.

When Not to Use Dispenso:
It's important to note that Dispenso is optimized for compute-bound tasks and might not be the best choice for scenarios involving high-latency task offload, such as networking or disk operations. In such cases, it may result in suboptimal performance.

Examples and Documentation:
Dispenso's documentation provides a variety of examples demonstrating its capabilities, such as how to use parallel_for for transforming sequential loops into parallel ones, how to manage task sets, and how to utilize futures for asynchronous operations.

In conclusion, Dispenso offers a robust set of tools for task parallelism in C++, making it a valuable resource for developers looking to leverage parallel computing in their applications. Its design for minimal dependencies and compatibility with modern C++ standards makes it a versatile choice for a wide range of projects.

For more detailed information and examples, you can visit the Dispenso documentation at facebookincubator.github.io/dispenso.