Complexity of Adding Coroutines in C++20 Compared to GoRoutines in Go

The addition of coroutines in C++20 is one of the most significant enhancements aimed at making asynchronous task handling more efficient. However, it has faced widespread criticism for its associated complexity and limited adoption so far. This article discusses the reasons behind this complexity, compares it with GoRoutines in Go, and proposes solutions for effective usage while anticipating its future in the programming world.

First: The Complexity of Coroutines in C++20

1. Flexible and Complex Design

Coroutines in C++ are designed as a low-level concept, granting developers complete freedom in determining how to use them. This makes them complex because developers must create their own infrastructure, such as:

• Managing state.

• Defining how values are returned or passed.

• Handling resources of suspended objects.

2. Lack of Standard Library Support

Unlike Go, which provides a standard library seamlessly integrated with GoRoutines, C++ lacks a comprehensive standard library to support coroutines. Most developers rely on external libraries such as:

• std::future and std::promise for basic value handling.

• Libraries like Boost.Asio and cppcoro to simplify coroutine usage.

3. Resource Management Complexity

Developers need to deeply understand resource management details. When a coroutine is suspended, they must ensure proper handling of objects and address unexpected scenarios like:

• Premature function termination.

• Releasing resources in case of task failure.

4. Compatibility with Legacy Code

Integrating coroutines with existing C++ code or systems may lead to complex challenges such as:

• Incompatibility with current execution models.

• The need to redesign code to adapt to the coroutine concept.

Second: Why Are GoRoutines Easier in Go?

1. Simple and High-Level Design

In Go, GoRoutines are designed as a high-level feature deeply integrated into the language. For example:

• Calling any function as a GoRoutine requires merely adding the go keyword before the call.

• Concurrent task management relies on a straightforward model using channels for communication.

2. Unified Execution Environment

Go provides a built-in execution environment supporting GoRoutines smoothly. Developers don't need to handle resource management or system design as Go handles it automatically.

3. Simplified State Management

Go automatically manages state and resources for GoRoutines, making them significantly easier to use compared to C++ coroutines.

4. Built-In Library Support

Go includes standard libraries specifically designed to directly support GoRoutines, reducing reliance on external libraries.

Third: How to Simplify Coroutines Usage in C++

1. Use External Libraries

Using libraries that facilitate coroutines can greatly simplify their implementation, such as:

• cppcoro: A library offering flexible structure and an easy interface for managing coroutines.

• Boost.Asio: A powerful library for handling networking and asynchronous tasks.

2. Rely on Standardized Interfaces

Future updates to C++ may introduce a standard library with better coroutine support, such as enhancements to the std::execution library or networking libraries.

3. Follow Best Practices

• Avoid writing raw coroutine code. Instead, use specialized wrappers to abstract complexity.

• Adopt the RAII (Resource Acquisition Is Initialization) approach for automatic resource management.

4. Learn the Basics of Coroutines

• Understand how co_yield, co_await, and co_return work.

• Learn concepts like Awaitable and Awaiter in C++.

Fourth: Comparison Between C++ Coroutines and GoRoutines

Fifth: The Future of Coroutines in C++

Future Improvements

• Upcoming C++ updates (such as C++23 and beyond) are expected to introduce standard libraries with better coroutine support.

• Enhancements in execution libraries and multithreading systems are anticipated.

Expanded Library Support

• The emergence of new libraries or improvements to existing ones, such as Boost and cppcoro, will simplify coroutine management.

Broader Usage

With the growing demand for asynchronous programming, coroutines are expected to gain more adoption, especially in areas like:

• Networking.

• Cloud computing.

• Game development.

Sixth: The Role of Companies and Experts in Simplifying Coroutines

Given the complexity of coroutines in C++, companies and experts have developed frameworks to make them more practical for various projects. Some notable efforts include:

1. cppcoro Library

• An open-source library designed to make working with coroutines easier and more seamless.

• Provides ready-made tools like:

  • async_generator: For asynchronous value generation.

  • task: A unit for organizing asynchronous tasks.

  • sync_wait: A utility for easily waiting for coroutine results.

2. Boost.Asio Library

• A prominent library that has long supported asynchronous programming in C++.

• With the advent of coroutines, it added features like co_spawn and awaitable for networking and high-performance applications.

3. Efforts by Leading Companies like Microsoft

• Microsoft has offered extensive coroutine support through its C++/WinRT framework, making them easier to use for Windows application development.

• C++/WinRT provides ready-made interfaces for working with coroutines, especially for UI programming and asynchronous services.

4. Internal Frameworks of Large Companies

• Companies like Google and Facebook have developed internal tools based on coroutines to simplify their use. However, these tools are often tailored for internal projects and not publicly available.

5. Future Efforts

• More libraries and frameworks leveraging coroutines are expected to emerge, such as:

  • Web server frameworks handling asynchronous requests efficiently.

  • Game engine libraries using coroutines for improved performance and task management in real time.

Conclusion

Although coroutines in C++20 currently pose significant challenges, they represent a critical step toward supporting asynchronous programming. Developers can overcome these complexities by using existing libraries and following best practices. With future updates and advancements in supporting tools, coroutines are likely to become more powerful and user-friendly.