Answers

Question 1

Atomic variables are thread-safe variables provided by Java.

They allow multiple threads to update a value safely without using synchronized blocks or locks.

Regular variables do not provide this protection and may cause race conditions.

Four classes from the java.util.concurrent.atomic package are:

AtomicInteger is used for thread-safe integer operations such as incrementing or decrementing a counter.

Atomic variables are useful for simple operations on a single variable.

For more complex operations involving multiple variables or multiple steps, locks are usually a better choice.

Yes. A program can be free of race conditions but still have poor performance.

Too much synchronization, lock contention, and thread management overhead can slow down the program.

Adding more threads does not always improve performance because threads compete for CPU time and shared resources.

In some cases, too many threads can actually reduce performance.

Deadlocks are difficult to detect because they depend on thread scheduling.

A program may work correctly many times and then suddenly deadlock under different execution conditions.