What are the commonly used thread safety tools in Java function libraries?

The Java function library provides thread-safe tools for multi-thread programming, including: Thread-safe collections: ConcurrentHashMap, ConcurrentLinkedQueue, CopyOnWriteArrayList Atomic variables: AtomicInteger, AtomicLong, AtomicReference Read-write locks: ReentrantLock, ReadWriteLock Synchronizers: CountDownLatch, Semaphore, CyclicBarrier These tools ensure safe access and updates to shared resources in a multi-threaded environment, preventing data inconsistencies and race conditions.

Commonly used thread safety tools in Java function libraries

In multi-threaded programming, thread safety is crucial to prevent Parallel execution leads to inconsistent state. Java libraries provide a wide range of thread-safety tools to help developers implement thread-safe and efficient applications.

Thread-safe collection

• ConcurrentHashMap: A concurrent hash table that provides efficient read and write operations and thread safety.
• ConcurrentLinkedQueue: A concurrent linked list that supports fast enqueueing and dequeuing as well as thread-safe access.
• CopyOnWriteArrayList: A concurrent array list with separate reading and writing. Each write operation will create a new copy of the list.

Atomic variable

• AtomicInteger: An atomic integer that supports thread-safe increment, decrement, and comparison operations.
• AtomicLong: An atomic long integer that provides the same thread-safe operations as AtomicInteger.
• AtomicReference: An atomic reference that supports thread-safe access and update of the reference type.

Read-write lock

• ReentrantLock: A reentrant lock that allows a thread to reentrant multiple times after acquiring the lock. Enter the same critical section.
• ReadWriteLock: A read-write lock that allows multiple threads to read shared data at the same time, but only one thread can write at a time.

Synchronizer

• CountDownLatch: A synchronizer that waits for a specific event to occur.
• Semaphore: A synchronizer used to control the number of concurrent threads.
• CyclicBarrier: A synchronizer used to coordinate threads to wait at the barrier.

Practical case

Consider a multi-threading scenario where multiple threads need to access shared data stored in a hash map. To ensure thread safety, you can use a ConcurrentHashMap and update it via a synchronized block:

import java.util.concurrent.ConcurrentHashMap;

public class ThreadSafeHashMap {
    private ConcurrentHashMap<String, Integer> sharedData = new ConcurrentHashMap<>();

    public void updateData(String key, int value) {
        synchronized (sharedData) {
            sharedData.put(key, value);
        }
    }
}

In this way, every time an update is made to the hash map, only one thread can access it, thus avoiding race conditions and The data is inconsistent.

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