Implementation and application of lock mechanism in Java parallel programming

In Java parallel programming, the lock mechanism is an important tool to control access to shared resources, including built-in locks, explicit locks and read-write locks. They are used to protect shared data, control access order and wait for thread tasks to complete. In a practical case, a built-in lock is used to protect access to bank account balances to ensure that concurrent access is safe and correct.

The locking mechanism in Java parallel programming

In Java parallel programming, the locking mechanism is used to control access to shared resources. vital tools for access. They prevent multiple threads from accessing shared data simultaneously, ensuring data consistency and program correctness.

Java provides a variety of locking mechanisms, including:

• Built-in locks (synchronized): Built-in locks are associated with the object itself and are controlled by using synchronized keyword to obtain.
• Explicit lock (Lock): Explicit lock is an interface provided in the Java concurrency package, which provides finer-grained control than built-in locks.
• Read-Write Lock (ReadWriteLock): Read-write lock allows multiple threads to obtain read-only access to shared resources at the same time, but only one thread can obtain write access.

Usage Scenarios

The lock mechanism has a variety of application scenarios in parallel programming, including:

• Protect shared data from subject to concurrent access.
• Control the order of access to resources.
• Wait for other threads to complete the task.

Practical Case: Bank Account

Consider the example of a bank account that can be accessed concurrently by multiple threads. To ensure the consistency of the account balance, access to this balance must be protected using a lock.

The Java code implemented using the built-in lock is as follows:

public class BankAccount {
    private int balance;

    public synchronized void deposit(int amount) {
        balance += amount;
    }

    public synchronized void withdraw(int amount) {
        if (amount <= balance)
            balance -= amount;
    }

    public int getBalance() {
        return balance;
    }
}

In the above example, the synchronized keyword is used to protect access to the balance variable . Any thread that attempts to access or modify balance must first acquire the object's lock. This ensures that only one thread can access the variable at a time.

Conclusion

The locking mechanism is crucial for Java parallel programming, which can ensure that concurrent access to shared resources is safe and correct. This article introduces the lock mechanisms provided by Java and their application scenarios, and provides a practical case to show how to use locks to protect shared data.

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