Java Threads and Concurrency Flashcards

What does the `volatile` keyword guarantee for a variable in Java?

Answer: Visibility — all threads see the most recent write to the variable

`volatile` ensures that reads and writes to a variable go directly to main memory, guaranteeing visibility of changes across threads.

Which method is used to start a thread's execution in Java?

Answer: start()

Calling `start()` on a `Thread` object creates a new OS thread and schedules the `run()` method for execution.

What is a race condition in Java concurrency?

Answer: Unpredictable behavior caused by multiple threads accessing shared data without proper synchronization

A race condition occurs when the program's outcome depends on the non-deterministic ordering of unsynchronized thread operations.

Which Java class provides a thread-safe, atomic integer that supports compound operations like increment?

Answer: AtomicInteger

`AtomicInteger` in `java.util.concurrent.atomic` provides atomic compound operations like `incrementAndGet()` without explicit synchronization.

In Java, which method pair is used for inter-thread communication?

Answer: notify() and wait()

`wait()` and `notify()` (with `notifyAll()`) on an `Object` are used for coordinating thread communication through a shared monitor.

What is the role of the `Executor` framework in Java concurrency?

Answer: To manage and reuse thread pools, decoupling task submission from execution

The `Executor` framework (in `java.util.concurrent`) manages thread pools, allowing efficient task submission without manual thread lifecycle management.