Ensuring Robustness with Bulletproof Disposable Types in Microsoft .NET

When conducting code reviews for .NET projects, one recurring issue that consistently tops the list is the failure of developers to call Dispose() on disposable objects. From the very inception of .NET, I have emphasized the paramount importance of this practice. Neglecting to handle disposable objects properly can lead to insidious virtual memory problems that might eventually cripple the application, causing servers to crash or users’ computers to freeze.

Once, during a comprehensive code review of a company’s code base, I held a meeting with the development manager. I inquired, “Do you encounter the need to reboot your backend servers regularly?” To my concern, the answer was a resounding “YES!” At that moment, I knew precisely what was amiss. The root cause of their recurring server issues was the widespread absence of Dispose() calls on disposable objects throughout their codebase. Addressing this problem became my priority, and it took nearly three months to rectify all instances.

Let this serve as a steadfast reminder to all developers to adopt a “bulletproof” approach when it comes to handling disposable types in .NET. By consistently calling Dispose() on disposable objects, we can fortify our applications against potential memory-related catastrophes, ensuring robust performance and smooth operation.

Simplifying Object Disposal with Spargine Extension Methods

Some time ago, I created a set of extension methods in Spargine to streamline the process of calling the Dispose() method.

Disposing Local Variables

To facilitate the disposal of variables, I developed the TryDispose() extension method. Below is an example demonstrating how to utilize this method:

disposableObject.TryDispose();

TryDispose() checks to ensure the object isn’t null and subsequently invokes Dispose().

Managing Disposable Fields

Handling disposable fields is equally important. To address this, I have implemented a method called DisposeFields(), following the proper IDisposable pattern. Let’s see it in action:

protected bool disposed;
public virtual void Dispose()
{
    Dispose(true);
    GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
    if (this.disposed)
    {
        return;
    }

    if (disposing)
    {
       this.DisposeFields();
    }
    this.disposed = true;
}

DisposeFields() examines all the fields in the object and invokes Dispose() on each of them if they implement the IDisposable interface. One of the significant advantages of this method is its ability to anticipate and prevent potential issues where another developer might add a new IDisposable field but forget to include it in the Dispose() call. This practice ensures what I like to call “Future Proofing.”

Disposing of Collections

For a considerable period, I’ve been utilizing these two extension methods. However, I once discovered that one of my clients is placing disposable objects into a collection. As it’s not a practice I’ve encountered before, I decided to create a new method called DisposeCollection() to handle this scenario. This method works with IEnumerable, IEnumerable<T>, and IDictionary<TKey, TValue>. In the DisposeFields() method, I check if the object supports IEnumerable; if it does, I proceed to call DisposeCollection() as well to ensure proper disposal of the contained disposable objects.

Ensuring There Are No Virtual Memory Leaks

While code analyzers can be helpful in identifying IDisposable issues, they may not catch every single problem. To thoroughly detect and resolve any issues related to virtual memory leaks, the most effective approach is to use a memory profiler. Running the code on a setup similar to the production environment is crucial for accurate results.

The memory profiler I rely on is called “.NET Memory Profiler” developed by SciTech Software AB. Having tried various profilers available, I have found this one to be the most effective. It facilitates easy navigation to the potential sources of memory leaks and provides visibility into the associated data. However, be aware that working with a profiler can be time-consuming due to the presence of false positives. Despite this, the benefits of using this memory profiler are significant, and I highly recommend exploring it before deploying your project to production.

Summary

For further guidance and insights, I highly recommend obtaining a copy of my book, “Rock Your Code: Coding Standards for Microsoft .NET” available on Amazon.com.

To analyze your code using the same settings I used in these articles, I encourage you to incorporate my EditorConfig file. It can be found at the following link: https://bit.ly/dotNetDaveEditorConfig. I update this file quarterly, so remember to keep yours up to date as well. I hope you will check out my OSS project Spargine by using this link: https://bit.ly/Spargine.

Please feel free to leave a comment below. I would appreciate hearing your thoughts and feedback.

Pick up any books by David McCarter by going to Amazon.com: http://bit.ly/RockYourCodeBooks

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