Java / Java Concurrency and Multi Threading in Java 17 and Java 21 Interview questions

What is thread priority in Java?

Thread priority is an integer hint, ranging from Thread.MIN_PRIORITY (1) to Thread.MAX_PRIORITY (10), with Thread.NORM_PRIORITY (5) as the default, that suggests to the thread scheduler how important a thread's execution is relative to others.

You set it with thread.setPriority(int) and read it with getPriority(). Higher-priority threads are more likely to be scheduled sooner or more often, but this is only a hint.

The actual scheduling behavior is delegated to the underlying operating system, so the effect of priority varies across platforms and JVM implementations, and it's never a substitute for correct synchronization. Relying on priority to guarantee ordering or exclusivity between threads is considered unreliable and is discouraged in production code.

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What is the default thread priority in Java? 10 (MAX_PRIORITY)

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5 (NORM_PRIORITY)

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1 (MIN_PRIORITY)

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Why shouldn't thread priority be relied on for correctness? Actual scheduling is OS-dependent and only a hint, not a guarantee

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Priority values are ignored by every JVM

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setPriority() throws an exception on every platform

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