Finalize vs Dispose in C# — The Subtle Art of Cleaning Up

Hello, .NET enthusiasts! 👋

Have you ever noticed how some objects seem to clean themselves up, while others require your explicit call to Dispose()? Or perhaps you’ve seen the mysterious ~ClassName() syntax and wondered if it’s the same as Dispose? Welcome to one of C#’s most overlooked yet crucial topics — understanding the difference between Finalize and Dispose.

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1) Why Cleanup Even Matters

Every application allocates memory, file handles, network connections, or database resources during its lifetime. Managed objects in .NET are automatically cleaned up by the Garbage Collector (GC), but unmanaged resources — like file streams, sockets, or database connections — don’t play by GC’s rules. That’s when we, as developers, must step in and guide .NET on how to tidy up properly.

In short: Finalize is the system’s fallback janitor, and Dispose is your personal cleanup plan.

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2) Meet Finalize — The Automatic Cleanup

The Finalize() method, also known as a destructor in C#, is automatically called by the Garbage Collector when an object is about to be destroyed. It’s your last chance to release unmanaged resources if you forgot to clean them earlier. But because the GC decides when to run it, you have no control over its timing.

Example

public class FileLogger
{
    private StreamWriter _writer;

    public FileLogger(string path)
    {
        _writer = new StreamWriter(path);
    }

    // Finalizer - runs automatically when GC collects
    ~FileLogger()
    {
        Console.WriteLine("Finalize called!");
        _writer?.Dispose();
    }

    public void Log(string message)
    {
        _writer.WriteLine(message);
    }
}

If you forget to close the file, the GC eventually calls Finalize(), which in turn disposes the file stream. Sounds convenient? Yes — but not efficient. You can’t predict when it will happen, and it keeps your object in memory longer.

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3) Enter Dispose — Your Manual Cleanup Plan

The Dispose() method belongs to the IDisposable interface. Unlike Finalize(), you control when it runs. It’s perfect for freeing unmanaged resources immediately after use — avoiding waiting for the Garbage Collector’s mercy.

Example

public class FileLogger : IDisposable
{
    private StreamWriter _writer;
    private bool _disposed;

    public FileLogger(string path)
    {
        _writer = new StreamWriter(path);
    }

    public void Log(string message)
    {
        if (_disposed)
            throw new ObjectDisposedException(nameof(FileLogger));

        _writer.WriteLine(message);
    }

    public void Dispose()
    {
        Console.WriteLine("Dispose called!");
        _writer?.Dispose();
        _disposed = true;
        GC.SuppressFinalize(this); // Prevent Finalize from running
    }

    ~FileLogger()
    {
        Dispose(); // safety net
    }
}

Here, calling Dispose() releases resources immediately, instead of waiting for garbage collection. Notice GC.SuppressFinalize(this)? That’s the polite way to tell .NET: “Thanks, I’ve already cleaned up. No need to call Finalize later.”

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4) Real-World Analogy — The Coffee Shop Cleanup ☕

Imagine running a coffee shop.

Finalize is like the cleaning staff that comes in at night. They clean up everything left behind — but only after closing hours. If you drop your coffee during the day, the spill stays until they arrive.

Dispose is you grabbing a napkin immediately after spilling coffee. You fix the mess instantly and keep the place running smoothly.

In software terms, relying on Finalize means waiting until the GC “feels like it,” while using Dispose gives you control to release memory or file locks as soon as you’re done.

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5) When to Use What

Use Dispose whenever you directly handle unmanaged resources — file handles, database connections, COM objects, etc. Use Finalize only when you absolutely must provide a backup in case someone forgets to call Dispose(). Most classes implement both: Dispose() for immediate cleanup and a finalizer as an insurance policy.

Luckily, with using statements (or await using in async code), you rarely need to worry manually:

Example

using (var logger = new FileLogger("app.log"))
{
    logger.Log("Application started...");
} // Dispose() called automatically here

The using statement ensures Dispose() runs automatically — even if an exception occurs. It’s the modern way to manage cleanup safely.

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6) The Hidden Performance Difference

Finalize() runs on a separate GC thread, which means your object can survive one or two extra GC cycles before it’s truly cleaned up. This delays memory recovery and increases GC workload.

Dispose(), on the other hand, happens instantly and deterministically. You know exactly when the resource is gone — making it faster, cleaner, and more predictable.

In production systems, waiting for Finalize() could mean your file handle stays open longer, causing file locks or “file already in use” errors — something you definitely don’t want in a busy service.

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7) A Real-Time Scenario

Think of a background process that writes logs every second. If you rely on Finalize(), it might keep the file locked even after the service stops. Now imagine another process tries to read or write to the same file — boom 💥, access denied.

Switch to Dispose(), and the file is released the moment your worker stops. The next process can safely take over without any conflict. That’s why all professional .NET logging frameworks (like Serilog or NLog) implement IDisposable.

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Wrapping Up

Both Finalize and Dispose are about cleaning up — the difference lies in who controls when it happens. Finalize is the system’s last resort; Dispose is your intentional cleanup. In modern .NET, always favor Dispose() (or using) and use Finalize() only as a backup plan.

After all, you wouldn’t wait until closing time to clean your own coffee spill — and you shouldn’t wait for the GC to clean up your code either.

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