Concurrency basics · interview question

Which changes would make the counter in a multi-threaded increment loop correct? Select all that apply.

Select all that applyMedium

Use an `AtomicInteger` and call `incrementAndGet()`.Do the increment inside a `synchronized` block on a shared lock.Declare the counter `volatile`.Use a `LongAdder` and call `increment()`.Call `Thread.yield()` after each increment.

Answer and explanation

Correct answer

A. Use an AtomicInteger and call incrementAndGet().
B. Do the increment inside a synchronized block on a shared lock.
D. Use a LongAdder and call increment().

Why

Atomics use CAS instructions; synchronized provides mutual exclusion; LongAdder spreads contention across cells and is fastest under heavy write contention.

References

The Java Tutorials: Concurrency

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Which changes would make the counter in a multi-threaded increment loop correct? Select all that apply.

Correct answer

Why

References

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