Green Threads vs Native Threads: Essential Concepts Quiz Quiz

Explore the differences between green threads and native threads, covering their functionality, advantages, limitations, and real-world use cases. This quiz helps you clarify threading concepts critical to high-performance and concurrent applications.

1. 1. Definition Check

   Which statement accurately describes a green thread?

   1. A hardware-level thread directly managed by the CPU
   2. A corrupted system process that slows down applications
   3. A thread managed by a virtual machine or runtime instead of the operating system
   4. A physical connection between two computers for data transfer

   Explanation: Green threads are managed in user space by a runtime or virtual machine, not by the operating system directly. Option B is incorrect since hardware-level threads refer to native or physical threads. Option C describes networking, not threading. Option D is unrelated to threading concepts.

2. 2. Operating System Dependency

   Which type of thread relies on scheduling and management from the operating system?

   1. Native thread
   2. Pseudo thread
   3. Fiber thread
   4. Green thread

   Explanation: Native threads are managed and scheduled by the operating system, allowing direct access to CPU cores and resources. Green threads, in contrast, are managed by user-level libraries. Fiber thread and pseudo thread are not standard terms or refer to different models; they do not fit the definition here.

3. 3. Concurrency and Parallelism

   Which statement is true about green threads and their ability to achieve parallelism on multi-core systems?

   1. Green threads must run faster than native threads on all systems
   2. Green threads are required for hardware-level parallelism
   3. Green threads are limited to concurrency but usually cannot utilize true parallelism across multiple CPU cores
   4. Green threads can always utilize all CPU cores simultaneously for parallel processing

   Explanation: Green threads typically run within a single operating system thread, so they provide concurrency but not hardware-level parallelism. Only native threads can use multiple CPU cores efficiently. Options B and C are incorrect; green threads do not inherently provide system-wide parallelism. Option D is false; execution speed depends on many factors.

4. 4. Context Switching Overhead

   Why do green threads usually have less context-switching overhead compared to native threads?

   1. Because green threads are always faster due to hardware acceleration
   2. Because native threads never switch contexts
   3. Because green threads are part of the network layer
   4. Because green threads avoid operating system context switching by managing scheduling in user space

   Explanation: Green threads perform context switching in user space, which avoids the overhead of kernel-mode switches and can make them lightweight. Option B is incorrect since hardware acceleration is not involved. Option C is false; native threads do switch contexts, just at the OS level. Option D is unrelated since threading is not part of the network layer.

5. 5. Blocking Operations

   If a green thread performs a blocking operation like reading a file, what is a potential issue?

   1. It pauses only itself without affecting other green threads
   2. It will enhance the speed of every green thread
   3. It can block all other green threads running within the same native thread
   4. It causes a system-level crash immediately

   Explanation: Since green threads share one native thread, if one green thread blocks, all others on that thread can be paused as well. Option B is incorrect; blocking does not enhance speed. Option C is only true for native threads, not green threads. Option D is extreme; blocking does not typically cause system-level crashes.

6. 6. Portability

   Which advantage do green threads have regarding portability?

   1. They only run on legacy systems
   2. They require specific hardware for execution
   3. They are designed to work the same way on different operating systems regardless of system thread support
   4. They are incompatible with mobile devices

   Explanation: Green threads are managed in user space, making them portable across systems that may lack native thread support. They do not depend on any specific hardware, making option B false. Option C is incorrect; green threads can run on many types of devices. Option D is misleading as modern and legacy systems may both support green threads.

7. 7. Use Case Example

   In which situation might green threads be preferred over native threads?

   1. When absolute maximum parallel CPU performance is essential
   2. When direct hardware interaction is necessary
   3. When only a few long-running, resource-intensive tasks are needed
   4. When running thousands of lightweight tasks that require quick context switches with minimal operating system overhead

   Explanation: Green threads are efficient for many small, short-lived operations due to lower context-switching overhead. Option B is better suited for native threads, which enable true parallelism. Option C requires OS-level threading for hardware interaction. Option D is typically handled well by native threads due to resource needs.

8. 8. Scalability Limitation

   What limits green threads from scaling efficiently on modern multi-core processors?

   1. They can only process graphical data
   2. They require special file systems to operate
   3. They are always blocked by network latency
   4. They are often restricted to running on a single core due to user-level scheduling

   Explanation: Green threads are managed in user space, which often limits them to one core unless specifically implemented otherwise. Option B is incorrect; network latency affects both thread types equally. Option C is unrelated to threading, and option D is false as green threads are not tied to special file systems.

9. 9. System Resource Consumption

   Compared to native threads, how do green threads typically affect system resource usage?

   1. They always consume more RAM due to extra scheduling code
   2. They require a dedicated CPU for each thread
   3. They usually consume less CPU and memory since they avoid OS-level overhead
   4. They use more network resources by default

   Explanation: Green threads use less system resources because their management is lightweight and operates in user space. Option B is incorrect; the extra scheduling code is minor compared to OS-level management. Option C is false; green threads do not need dedicated CPUs. Option D is unrelated, as threading does not directly impact network usage.

10. 10. Thread Visibility

    Who is responsible for scheduling and managing green threads during execution?

    1. The network administrator
    2. A user-level runtime or library implemented above the operating system
    3. The file system manager
    4. The hardware BIOS chip

    Explanation: Green threads are controlled by user-level software, not directly by the operating system. Network administrators (option B) and file system managers (option C) do not handle thread scheduling. The BIOS (option D) is low-level firmware and is unrelated to thread management.