What Are the Benefits of Using Synchronized Methods Over Synchronized Blocks in Java?

What are the benefits of using synchronized methods over synchronized blocks in Java?

public synchronized void synchronizedMethod() {
    // critical section
}

public void synchronizedBlockMethod() {
    synchronized(this) {
        // critical section
    }
}

In Java, synchronization is crucial to prevent thread interference when multiple threads access shared resources. Synchronized methods and blocks are two mechanisms to achieve this, but they serve different purposes and come with distinct advantages and disadvantages. Understanding these can help you write more efficient and clear concurrent Java applications.

public class Counter {
    private int count = 0;

    // Synchronized method
    public synchronized void increment() {
        count++;
    }

    // Synchronized block
    public void incrementPartially() {
        // Some non-critical code
        synchronized(this) {
            count++;
        }
    }
}

Causes

• Synchronized methods lock the entire method, preventing any other thread from accessing the same method on the same object.
• Synchronized blocks allow finer control over the synchronization scope, locking only the necessary parts instead of the whole method.

Solutions

• Use synchronized methods for simplicity when dealing with object-level locking, especially when the entire method needs to be synchronized.
• Use synchronized blocks when only a portion of the method requires synchronization, allowing the rest of the method to execute without delays, which can improve performance in multi-threaded applications.

Mistake: Using synchronized methods when only a small portion of the code needs to be synchronized, causing unnecessary locking.

Solution: Use synchronized blocks to limit the scope of synchronization to only the critical sections.

Mistake: Failing to understand that synchronized methods can lead to performance bottlenecks if heavily used in a multi-threaded environment.

Solution: Evaluate the granularity of your synchronization and use synchronized blocks where appropriate to enhance concurrency.