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Overview
The article discusses the implementation of Futures for C++11 at Facebook, highlighting the benefits of asynchronous programming and how it improves performance and code readability. It introduces the Folly Futures library, which allows developers to manage asynchronous computations more effectively compared to traditional callback methods.
What You'll Learn
1
How to implement asynchronous computations using Folly Futures
2
Why using Futures can reduce latency and improve throughput in services
3
When to use callbacks versus Futures for better code readability
4
How to handle exceptions in asynchronous code with Futures
Prerequisites & Requirements
- Basic understanding of asynchronous programming concepts
- Folly library for C++(optional)
Key Questions Answered
What are the advantages of using Futures over traditional callbacks?
Futures provide a cleaner and more composable way to handle asynchronous computations, reducing complexity and improving code readability. They allow for chaining of operations and better error handling, which helps avoid common pitfalls like 'callback hell'.
How does the Folly Futures library improve performance?
Folly Futures allows for efficient handling of asynchronous tasks, enabling services to process multiple requests concurrently without blocking threads. This leads to reduced latency and better resource utilization, as demonstrated in case studies from Facebook and Instagram.
What is the role of the Executor interface in Futures?
The Executor interface in Folly Futures allows developers to control the execution context of callbacks, enabling them to optimize performance by managing how and where asynchronous tasks are executed, such as offloading CPU-intensive work from I/O threads.
How can Futures help manage errors in asynchronous programming?
Futures encapsulate the result of an asynchronous operation, which can either be a value or an exception. This design helps ensure that errors are handled consistently, as exceptions can be processed using the onError method or retrieved with the value method.
Key Statistics & Figures
Reduction in tail latencies at Instagram
tenfold
This improvement was achieved by converting their recommendation service from synchronous to asynchronous using Futures.
Reduction in average latency for Facebook's News Feed service
two-thirds
This was accomplished by transitioning to a Futures-based implementation that allowed for more granular timeout handling.
Technologies & Tools
Library
Folly
Used for implementing Futures in C++11 at Facebook.
Key Actionable Insights
1Adopt Futures for managing asynchronous operations in your C++ projects to enhance code clarity and maintainability.Using Futures can significantly simplify the handling of asynchronous tasks, making it easier to reason about the flow of data and error handling, ultimately leading to more robust applications.
2Utilize the Executor interface to optimize the execution context of your asynchronous tasks.By controlling where and how your callbacks execute, you can improve performance and responsiveness, especially in high-load scenarios where resource management is critical.
3Implement error handling in your Futures to avoid losing track of exceptions.By using the onError method provided by Futures, you can ensure that exceptions are properly managed and do not lead to unexpected behavior in your applications.
Common Pitfalls
1
Developers often struggle with 'callback hell' when using traditional asynchronous programming techniques.
This occurs when multiple nested callbacks make the code difficult to read and maintain. Using Futures can help flatten this structure and improve code clarity.
Related Concepts
Asynchronous Programming Patterns
Error Handling In Asynchronous Code
Performance Optimization Techniques