A financial trading application processes high-volume transactions. The system uses a multithreaded architecture where multiple threads update a shared Account object's balance field. Recently, intermittently incorrect balance calculations have been reported. Developers suspect a race condition on the balance field. The Account class is defined as follows:

public class Account {
private double balance = 0.0;
public void deposit(double amount) { balance += amount; }
public void withdraw(double amount) { balance -= amount; }
public double getBalance() { return balance; }
}

Threads are created using ExecutorService with a fixed thread pool. The issue occurs only under heavy load. Which course of action should the development team take to resolve the issue while maintaining performance?

Question

A financial trading application processes high-volume transactions. The system uses a multithreaded architecture where multiple threads update a shared Account object's balance field. Recently, intermittently incorrect balance calculations have been reported. Developers suspect a race condition on the balance field. The Account class is defined as follows:

public class Account {
    private double balance = 0.0;
    public void deposit(double amount) { balance += amount; }
    public void withdraw(double amount) { balance -= amount; }
    public double getBalance() { return balance; }
}

Threads are created using ExecutorService with a fixed thread pool. The issue occurs only under heavy load. Which course of action should the development team take to resolve the issue while maintaining performance?

Accepted Answer

Synchronize the deposit and withdraw methods.. Synchronizing the `deposit` and `withdraw` methods ensures mutual exclusion on the `balance` field. In Java, the compound operations `balance += amount` and `balance -= amount` are not atomic; they involve a read, modify, and write sequence. Synchronization guarantees that only one thread executes these methods at a time, preventing race conditions and ensuring correct balance calculations under heavy load.

Answer

Declare the balance field as volatile.

Answer

Use AtomicLong and convert to double.

Answer

Wrap the balance field in a synchronized block within each method using a separate lock object.

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