For what reasons is the use of the term 'lightweight threads' for coroutines considered incorrect?
sobes.tech AI
Answer from AI
The term "lightweight threads" for coroutines is considered incorrect for several reasons:
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Difference in nature: Threads are system objects managed by the operating system, with their own stack and execution context. Coroutines are user objects that implement cooperative multitasking within a single thread.
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Switching mechanism: Threads are switched by the OS scheduler, which incurs overhead for context switching. Coroutines are switched explicitly in code (yield, suspend), which is much cheaper.
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Parallelism vs Concurrency: Threads can run in parallel on multiple cores, while coroutines usually run in a single thread, providing concurrency but not parallelism.
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Resources: Threads require allocation of system resources (stack, descriptors), whereas coroutines have minimal overhead as they are just objects and state in memory.
Therefore, coroutines are better viewed as a separate mechanism of asynchronous programming rather than "lightweight threads".