Item Be careful when optimizing

1. Avoid Premature Optimization
Main maxims:

• Performance is often sacrificed in the name of unnecessary optimizations.
• Premature optimization is considered the "root of all evil" in programming.

The recommended rules are:

• Rule 1: Don’t optimize.
• Rule 2: Only optimize when the need is clear and unavoidable.

2. Focus on Clear and Correct Code Architecture

• Initial objective: Create well-structured, maintainable programs before focusing on performance.
• If the architectural foundation is solid, optimizations can be added later without compromising the integrity of the code.
• Encapsulation: Use information hiding to isolate design choices, facilitating local changes and improvements without impacting the system as a whole.

3. Consider Performance in Initial Design, but Avoid Premature Commitments

• During design, avoid choices that restrict future performance, especially in:
• APIs: Ensure that critical methods do not add performance penalties, such as creating unnecessary objects.
• Persistent data formatting: Choose data formats that allow for flexibility and efficiency.
• Example of inefficient API: The getSize method of the java.awt.Component class returns a mutable Dimension object, requiring unnecessary allocations and impacting performance.

4. Evaluate Performance with Appropriate Tools (Profiling and Benchmarking)

• Profilers: Use profiling tools to identify where the program consumes the most time, avoiding optimizing parts that are not the real bottleneck.
• Example tool: jmh (Java Microbenchmark Harness) is recommended for detailed performance micro-benchmarking in Java.
• Profiling helps identify inefficient algorithms (e.g. quadratic) that should be replaced with more efficient algorithms before focusing on low-level improvements.

5. Consider Portability and Performance Variability in Different

• Implementations and Hardware
• Performance in Java can vary widely between JVM versions, hardware platforms, and configurations.
• It is important to check optimizations across all target platforms to ensure consistency of performance.

6. Post-Development Optimization Process
Recommended steps:

• Finalize the design and implement a clear and concise version of the program.
• Evaluate overall performance. If necessary, locate and optimize the areas that most affect performance.
• Prioritize the choice of efficient algorithms; an inappropriate choice of algorithm is not resolved with low-level optimizations.
• Measure performance after each adjustment to confirm positive impact.

Final Summary

• Best practice: Focus on writing quality code, as good design is generally compatible with efficient performance.
• Constant evaluation: Always measure the impact of optimizations on performance.
• General example: When critical methods impact efficiency due to unnecessary objects, consider alternatives such as immutable types or methods that return primitive values ​​instead of objects, reducing allocations and making the program faster and more efficient.

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