Add virtual-threads.md documentation for Project Loom

[Copilot]

Create comprehensive technical documentation for Virtual Threads in Java (Project Loom) with 60 code examples.

Status: Incomplete

Task was to create virtual-threads.md covering:

• Introduction and background on Java concurrency
• Virtual thread concepts and creation patterns
• Performance/scalability characteristics
• Integration with existing APIs and structured concurrency
• Use cases, limitations, and best practices

What was done:

• Analyzed repository structure and markdown conventions
• Reviewed existing docs (concurrency.md, floating-point.md) for style guidelines
• Identified formatting requirements: Java 25 features, void main(), IO.println, 80-char lines

Blocked:

• Unable to write file content due to tool execution issues
• The virtual-threads.md file remains empty

To complete:
Populate virtual-threads.md following the established pattern from concurrency.md with examples like:

void main() throws InterruptedException {

    var thread = Thread.startVirtualThread(() -> {
        IO.println("Running on: " + Thread.currentThread());
    });

    thread.join();
}

Original prompt

On virtual-threads.md, Create a detailed technical document explaining Virtual Threads in Java (Project Loom). create 60 examples.

The document should include:

1. Introduction

   • Define virtual threads and their purpose.
   • Explain how they differ from traditional platform threads.
   • Highlight why Project Loom was introduced.

2. Background

   • Brief history of Java concurrency (threads, executors, fork/join).
   • Limitations of traditional threading (resource-heavy, scalability issues).

3. What are Virtual Threads?

   • Explain the concept of lightweight threads managed by the JVM.
   • Describe how they decouple concurrency from OS threads.
   • Provide diagrams showing the difference between platform threads and virtual threads.

4. Creating Virtual Threads

   • Show code examples using Thread.ofVirtual().start(...).
   • Demonstrate usage with Executors.newVirtualThreadPerTaskExecutor().
   • Compare syntax with traditional thread creation.

5. Performance and Scalability

   • Explain how virtual threads allow millions of concurrent tasks.
   • Discuss reduced memory footprint and context-switching overhead.
   • Provide benchmarks or conceptual comparisons.

6. Integration with Existing APIs

   • Show how virtual threads work seamlessly with blocking I/O.
   • Explain compatibility with existing Java concurrency utilities.
   • Discuss structured concurrency (scoped values, task grouping).

7. Use Cases

   • Server-side applications (handling thousands of requests).
   • Parallel data processing.
   • Simplifying asynchronous programming.

8. Limitations and Considerations

   • Current restrictions (e.g., thread-local usage, debugging challenges).
   • Potential pitfalls when migrating from traditional threads.
   • Discuss maturity and adoption status.

9. Best Practices

   • Guidelines for when to use virtual threads vs platform threads.
   • Tips for writing scalable, maintainable concurrent code.
   • Monitoring and profiling virtual-thread applications.

10. Conclusion

    • Summarize the importance of virtual threads.
    • Emphasize how they simplify concurrency and improve scalability in modern Java.

Formatting Requirements:

• Use clear section headings.
• Include code snippets for clarity.
• Provide diagrams or tables to illustrate differences between thread models.
• Write in a professional, educational tone suitable for intermediate to advanced Java developers.
• Ensure the document is cohesive, well-organized, and easy to follow.

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