Object Lifecycle - Understanding How Objects Live and Die in C#

Vaibhav • September 10, 2025

In the previous article, we explored the this keyword - a powerful tool for referring to the current object instance and resolving naming conflicts. Now, we shift our focus to a broader topic that governs how objects behave over time: the object lifecycle.

Every object in C# goes through a lifecycle: it is created, used, and eventually cleaned up. Understanding this lifecycle is essential for writing efficient, safe, and predictable code. In this article, we’ll explore how objects are constructed, how their lifetime is managed by the .NET runtime, and how you can hook into lifecycle events using constructors, destructors, and the garbage collector.

Object Creation

The lifecycle of an object begins when it is created using the new keyword. This allocates memory on the heap and calls the class’s constructor to initialize its state.

public class User
{
    public string Username { get; }

    public User(string username)
    {
        Username = username;
    }
}

When you create a new User object, the constructor runs and sets the initial value of Username:

User u = new User("vaibhav");

At this point, the object is fully initialized and ready to be used. It lives on the heap and remains in memory as long as it is reachable.

Object Usage

Once an object is created, you can interact with it through its methods and properties. This is the active phase of its lifecycle, where it performs its intended behavior.

Console.WriteLine(u.Username);

During this phase, the object may hold resources, maintain state, and collaborate with other objects. It remains alive as long as there are references to it in your code.

Object Cleanup and Destruction

When an object is no longer needed and no references to it remain, it becomes eligible for garbage collection. The .NET runtime uses a garbage collector (GC) to automatically reclaim memory.

You do not need to manually delete objects in C#. The GC runs periodically and frees memory for unreachable objects. However, if your object holds unmanaged resources (like file handles or database connections), you should release them explicitly.

Using Destructors

A destructor (also called a finalizer) is a special method that runs when the object is being collected by the GC. It allows you to clean up unmanaged resources.

public class FileLogger
{
    private string filePath;

    public FileLogger(string path)
    {
        filePath = path;
        // Open file or allocate resource
    }

    ~FileLogger()
    {
        // Cleanup logic
        Console.WriteLine("Destructor called for FileLogger");
    }
}

The destructor runs automatically when the object is finalized. You cannot predict exactly when this happens - it depends on the GC’s schedule.

Implementing IDisposable

The recommended way to release resources in C# is to implement the IDisposable interface. This allows consumers of your class to call Dispose() explicitly.

public class FileLogger : IDisposable
{
    private FileStream stream;
    private bool disposed = false;

    public FileLogger(string path)
    {
        stream = new FileStream(path, FileMode.Create);
    }

    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    protected virtual void Dispose(bool disposing)
    {
        if (!disposed)
        {
            if (disposing)
            {
                stream?.Dispose();
            }

            disposed = true;
        }
    }

    ~FileLogger()
    {
        Dispose(false);
    }
}

This pattern ensures that resources are released properly. The Dispose() method can be called explicitly, and the finalizer acts as a backup.

Using using Statements

When you use a class that implements IDisposable, you should call Dispose() when you’re done. The easiest way to do this is with a using statement.

using (FileLogger logger = new FileLogger("log.txt"))
{
    // Use logger
} // Dispose() is called automatically here

The using statement ensures that Dispose() is called even if an exception occurs. This is the preferred way to manage resources in C#.

Garbage Collection Details

The .NET garbage collector is automatic and generational. It divides objects into generations based on their age:

• Generation 0: Newly created objects.
• Generation 1: Objects that survived one collection.
• Generation 2: Long-lived objects.

The GC collects Generation 0 frequently, Generation 1 less often, and Generation 2 rarely. This optimizes performance and reduces overhead.

You can force a collection using GC.Collect(), but this is discouraged unless absolutely necessary.

GC.Collect(); // Forces garbage collection

Use this only for diagnostic or emergency scenarios. Let the runtime manage memory in most cases.

Object Lifetime and Scope

An object’s lifetime depends on its scope and references. Local variables are collected when they go out of scope. Objects referenced by fields or static members may live longer.

public void CreateUser()
{
    User u = new User("vaibhav");
    // u is alive here
}
// u is out of scope and eligible for GC

If you store the object in a static field, it remains alive until the application ends:

public static User CurrentUser = new User("vaibhav");

Be mindful of object references to avoid memory leaks.

Finalization Queue and GC.SuppressFinalize

When an object has a destructor, it is placed in the finalization queue. This delays collection and adds overhead. If you’ve already cleaned up resources in Dispose(), you can call GC.SuppressFinalize(this) to skip finalization.

public void Dispose()
{
    Dispose(true);
    GC.SuppressFinalize(this);
}

This improves performance and avoids redundant cleanup.

Summary

The object lifecycle in C# includes creation, usage, and cleanup. Objects are created using constructors, used through methods and properties, and cleaned up by the garbage collector. For unmanaged resources, you should implement IDisposable and use Dispose() to release them deterministically.

We explored destructors, finalization, garbage collection, and the using statement. We also discussed object scope, lifetime, and best practices for resource management.

Understanding the object lifecycle helps you write efficient, safe, and maintainable code. It ensures that your objects behave predictably and that resources are released properly.

In the next article, we’ll explore Class Design Principles - how to structure classes for clarity, cohesion, and long-term maintainability.