Difference between Coroutine and Java Thread?

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KotlinIntermediate4 min

Answer

Feature	Java Thread	Kotlin Coroutine
Weight	Heavyweight (OS managed)	Lightweight (User-space managed)
Memory	~1MB stack per thread	~KB per coroutine
Creation	Expensive	Cheap
Blocking	Blocks the thread when waiting	Suspends (frees thread) when waiting
Context Switching	OS Kernel switch (expensive)	Software switch (fast)
Scalability	Limited (thousands max)	Massive (millions possible)

Key Concept: Coroutines are "computations that can be suspended". They can pause execution without blocking the underlying thread, allowing that thread to do other work.

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