How does an object behave when it is modified simultaneously from multiple threads?

When an object is modified simultaneously from multiple threads without proper synchronization, it leads to a race condition. As a result:

• Data can become inconsistent or corrupted.
• Program behavior becomes unpredictable and difficult to debug.
• Errors such as lost updates, partial changes, or crashes may occur.

To prevent such issues, synchronization mechanisms should be used, for example:

• synchronized blocks or methods in Java/Kotlin.
• Classes from java.util.concurrent, such as ReentrantLock.
• Use of thread-safe collections and atomic operations.

Example of using synchronized in Kotlin:

class Counter {
    private var count = 0

    @Synchronized
    fun increment() {
        count++
    }

    fun getCount(): Int = count
}

Without synchronization, multiple threads can read and write to count simultaneously, leading to incorrect results.