Pledge is a lightweight reactive programming framework for Swift designed to be simpler and more performant than RxSwift. It aims to provide a more accessible entry point to reactive programming by offering a reduced API surface, focusing on core functionalities like observables, operators, and subjects. Pledge avoids the overhead associated with RxSwift, leading to improved compile times and runtime performance, particularly beneficial for smaller projects or those where resource constraints are a concern. The framework embraces Swift's concurrency features, enabling seamless integration with async/await for modern Swift development. Its goal is to offer the benefits of reactive programming without the complexity and performance penalties often associated with larger frameworks.
Coroutines offer a powerful abstraction for structuring programs involving asynchronous operations or generators, providing a more manageable alternative to callbacks or complex state machines. They achieve this by allowing functions to suspend and resume execution at specific points, enabling cooperative multitasking within a single thread. This post emphasizes that the key benefit of coroutines isn't simply the syntactic sugar of async and await, but the fundamental shift in how control flow is managed. By enabling the caller and the callee to cooperatively schedule their execution, coroutines facilitate the creation of cleaner, more composable, and easier-to-reason-about asynchronous code. This cooperative scheduling, controlled by the programmer, distinguishes coroutines from preemptive threading, offering more predictable and often more efficient concurrency management.
Hacker News users discuss the nuances of coroutines and their various implementations. Several commenters highlight the distinction between stackful and stackless coroutines, emphasizing the performance benefits and limitations of each. Some discuss the challenges in implementing stackful coroutines efficiently, while others point to the relative simplicity and portability of stackless approaches. The conversation also touches on the importance of understanding the underlying mechanics of coroutines and their impact on program behavior. A few users mention specific language implementations and libraries for working with coroutines, offering examples and insights into their practical usage. Finally, some commenters delve into the more philosophical aspects of the article, exploring the trade-offs between different programming paradigms and the importance of choosing the right tool for the job.
ArkFlow is a high-performance stream processing engine written in Rust, designed for building and deploying real-time data pipelines. It emphasizes low latency and high throughput, utilizing asynchronous processing and a custom memory management system to minimize overhead. ArkFlow offers a flexible programming model with support for both stateless and stateful operations, allowing users to define complex processing logic using familiar Rust syntax. The framework also integrates seamlessly with popular data sources and sinks, simplifying integration with existing data infrastructure.
Hacker News users discussed ArkFlow's performance claims, questioning the benchmarks and the lack of comparison to existing Rust streaming engines like tokio-stream. Some expressed interest in the project but desired more context on its specific use cases and advantages. Concerns were raised about the crate's maturity and potential maintenance burden due to its complexity. Several commenters noted the apparent inspiration from Apache Flink, suggesting a comparison would be beneficial. Finally, the choice of using async for stream processing within ArkFlow generated some debate, with users pointing out potential performance implications.
Combining Tokio's asynchronous runtime with prctl(PR_SET_PDEATHSIG) in a multi-threaded Rust application can lead to a subtle and difficult-to-debug issue. PR_SET_PDEATHSIG causes a signal to be sent to a child process when its parent terminates. If a thread in a Tokio runtime calls prctl to set this signal and then that thread's parent exits, the signal can be delivered to a different thread within the runtime, potentially one that is unprepared to handle it and is holding critical resources. This can result in resource leaks, deadlocks, or panics, as the unexpected signal disrupts the normal flow of the asynchronous operations. The blog post details a specific scenario where this occurred and provides guidance on avoiding such issues, emphasizing the importance of carefully considering signal handling when mixing Tokio with prctl.
The Hacker News comments discuss the surprising interaction between Tokio and prctl(PR_SET_PDEATHSIG). Several commenters express surprise at the behavior, noting that it's non-intuitive and potentially dangerous for multi-threaded programs using Tokio. Some point out the complexities of signal handling in general, and the specific challenges when combined with asynchronous runtimes. One commenter highlights the importance of understanding the underlying system calls and their implications, especially when mixing different programming paradigms. The discussion also touches on the difficulty of debugging such issues and the lack of clear documentation or warnings about this particular interaction. A few commenters suggest potential workarounds or mitigations, including avoiding PR_SET_PDEATHSIG altogether in Tokio-based applications. Overall, the comments underscore the subtle complexities that can arise when combining asynchronous programming with low-level system calls.
The blog post argues for a standardized, cross-platform OS API specifically designed for timers. Existing timer mechanisms, like POSIX's timerfd and Windows' CreateWaitableTimer, while useful, differ significantly across operating systems, complicating cross-platform development. The author proposes a new API with a consistent interface that abstracts away these platform-specific details. This ideal API would allow developers to create, arm, and disarm timers, specifying absolute or relative deadlines with optional periodic behavior, all while handling potential issues like early wake-ups gracefully. This would simplify codebases and improve portability for applications relying on precise timing across different operating systems.
The Hacker News comments discuss the complexities of cross-platform timer APIs, largely agreeing with the article's premise. Several commenters highlight the difficulties introduced by different operating systems' power management features, impacting timer accuracy and reliability. Specific challenges like signal coalescing and the lack of a unified interface for monotonic timers are mentioned. Some propose workarounds like busy-waiting for short durations or using platform-specific code for optimal performance. The need for a standardized API is reiterated, with suggestions for what such an API should offer, including considerations for power efficiency and different timer resolutions. One commenter points to the challenges of abstracting away hardware differences completely, suggesting the ideal solution may involve a combination of OS-level improvements and application-specific strategies.
The article "The Mythical IO-Bound Rails App" argues that the common belief that Rails applications are primarily I/O-bound, and thus not significantly impacted by CPU performance, is a misconception. While database queries and external API calls contribute to I/O wait times, a substantial portion of a request's lifecycle is spent on CPU-bound activities within the Rails application itself. This includes things like serialization/deserialization, template rendering, and application logic. Optimizing these CPU-bound operations can significantly improve performance, even in applications perceived as I/O-bound. The author demonstrates this through profiling and benchmarking, showing that seemingly small optimizations in code can lead to substantial performance gains. Therefore, focusing solely on database or I/O optimization can be a suboptimal strategy; CPU profiling and optimization should also be a priority for achieving optimal Rails application performance.
Hacker News users generally agreed with the article's premise that Rails apps are often CPU-bound rather than I/O-bound, with many sharing anecdotes from their own experiences. Several commenters highlighted the impact of ActiveRecord and Ruby's object allocation overhead on performance. Some discussed the benefits of using tools like rack-mini-profiler and flamegraphs for identifying performance bottlenecks. Others mentioned alternative approaches like using different Ruby implementations (e.g., JRuby) or exploring other frameworks. A recurring theme was the importance of profiling and measuring before optimizing, with skepticism expressed towards premature optimization for perceived I/O bottlenecks. Some users questioned the representativeness of the author's benchmarks, particularly the use of SQLite, while others emphasized that the article's message remains valuable regardless of the specific examples.
Pyper simplifies concurrent programming in Python by providing an intuitive, decorator-based API. It leverages the power of asyncio without requiring explicit async/await syntax or complex event loop management. By simply decorating functions with @pyper.task, they become concurrently executable tasks. Pyper handles task scheduling and execution transparently, making it easier to write performant, concurrent code without the typical asyncio boilerplate. This approach aims to improve developer productivity and code readability when dealing with concurrency.
Hacker News users generally expressed interest in Pyper, praising its simplified approach to concurrency in Python. Several commenters compared it favorably to existing solutions like multiprocessing and Ray, highlighting its ease of use and seemingly lower overhead. Some questioned its performance characteristics compared to more established libraries, and a few pointed out potential limitations or areas for improvement, such as handling large data transfers between processes and clarifying the licensing situation. The discussion also touched upon potential use cases, including simplifying parallelization in scientific computing. Overall, the reception was positive, with many commenters eager to try Pyper in their own projects.
Summary of Comments ( 2 )
https://news.ycombinator.com/item?id=43641576
HN commenters generally expressed skepticism towards Pledge's performance claims, particularly regarding the "no Rx overhead" assertion. Several pointed out the difficulty of truly eliminating the overhead associated with reactive programming patterns and questioned whether a simpler approach using Combine, Swift's built-in reactive framework, wouldn't be preferable. Some questioned the need for another reactive framework in the Swift ecosystem given the existing mature options. A few users showed interest in the project, acknowledging the desire for a lighter-weight alternative to Combine, but emphasized the need for robust benchmarks and comparisons to substantiate performance claims. There was also discussion about the project's name and potential trademark issues with Adobe's Pledge image format.
The Hacker News post discussing Pledge, a lightweight reactive framework for Swift, has generated a moderate amount of discussion, with several commenters expressing interest and raising pertinent questions.
One of the most compelling threads revolves around the performance comparisons between Pledge and Combine, Apple's built-in reactive framework. A commenter questions the benchmark presented in the project's README, specifically pointing out that Combine's performance is known to be suboptimal when dealing with a large number of subscribers and frequent updates. They suggest that a more realistic benchmark would involve scenarios with a substantial subscriber count and rapid value changes to accurately gauge Pledge's performance advantage. The author of Pledge responds to this, acknowledging the feedback and indicating their intention to incorporate more comprehensive benchmarks in the future. They also discuss the inherent difficulties in creating a completely fair comparison given the differences in the frameworks' architectures.
Another significant point of discussion is the project's scope and goals. A commenter asks whether Pledge intends to be a full-fledged reactive framework like Combine or a more focused solution addressing specific use cases. The project author clarifies that Pledge prioritizes simplicity and performance, aiming to provide a lightweight alternative for common reactive patterns without the complexity and overhead of Combine. They emphasize that Pledge isn't designed to be a complete replacement for Combine but rather a more streamlined option for specific scenarios.
Several commenters express general interest in the project and commend its approach. Some suggest potential improvements, including exploring alternative implementation strategies and considering compatibility with Swift's existing concurrency features.
Finally, there's a brief discussion regarding the project's license. A commenter notes the absence of a license file and inquires about the intended licensing terms. The author promptly addresses this by adding an MIT license to the repository.
Overall, the comments on the Hacker News post reflect a positive reception of Pledge. The discussion focuses primarily on performance comparisons with Combine, the project's overall goals, and potential areas for improvement. The author actively engages with commenters, addressing their questions and demonstrating a willingness to incorporate feedback.