# Migrating from Developing Asynchronous Multi-Threading Programs to Reactive Programs in Java
## 7 Evaluation of Results
### Performance Analysis
#### 7.2.4 Trade-Offs and Long-Term Impacts  
For reactive programming to gain broader adoption in modern software solutions, its advantages must be weighed against the challenges it introduces, especially when compared to traditional asynchronous approaches. Understanding how each paradigm stands in terms of learning curves, development and debugging complexities, and long-term maintainability is essential for deciding about their use. Reactive programming introduces a paradigm shift, employing a declarative, event-driven approach, which should be adopted by developers. Reactive programming successfully abstracts some of the complexities of thread management, but it also demands a deep understanding of data flows, operators, and event-driven interactions. The initial development effort and complexity can be considerable for teams unfamiliar with reactive principles, potentially impacting the deliverables and timelines of projects [66]. On the other hand, asynchronous programs require more explicit management and orchestration of thread pools, which includes avoiding common pitfalls encountered in concurrent programming by adopting or implementing more sophisticated concurrency management mechanisms [11]. Both paradigms present trade-offs in complexity, but the choice should be dictated primarily by the specific use cases and the team's expertise and adaptability. Debugging reactive applications requires particular tools and approaches due to their declarative character. Traditional debugging methods, such as code stepping or monitoring thread execution, might be less effective in reactive environments due to the event-driven architecture. Auxiliary tools are available to assist with some of the challenges, but they also introduce additional dependencies and learning curves for developers [67]. In contrast, debugging asynchronous applications often revolves around understanding thread execution, race conditions, and deadlocks, which, although complicated, are more commonly encountered and, therefore, better documented, with multiple approaches available for circumventing them [12]. While reactive programming mitigates some issues through abstractions, it introduces different challenges, such as data flow tracing and complex operator chain management, highlighting the distinct approaches each paradigm requires for addressing debugging complexities. Reactive codebases can be more concise and modular when effectively written, adhering to the declarative style of the paradigm, which often leads to improved maintainability. This modularity allows for easier changes and updates, particularly in complex, highly concurrent systems where flexibility is critical. However, the inherent complexities of the paradigm, such as the use of reactive operators and operator chains, can make the codebase harder to understand for new developers or those unfamiliar with its principles. Research has shown that reactive programming often increases cyclomatic complexity and may be less readable according to traditional readability metrics, posing challenges for team onboarding and overall code comprehension [68]. In contrast, asynchronous programming, while more familiar to many Java developers, relies on traditional imperative patterns, which are more verbose and may be easier to debug and maintain but harder to scale or refactor effectively. The long-term maintainability of reactive programming heavily depends on appropriate training, thorough documentation, and adherence to best practices established from the beginning of the development process. Adopting the reactive paradigm can be challenging for developers accustomed to traditional asynchronous development, as the two paradigms propose significantly different approaches. While asynchronous programming typically relies on callbacks and manual thread management to handle concurrent operations, the reactive approach abstracts these complexities through reactive streams and declarative constructs.