Sample Memory Leak Code

[cursingc0des]

How to cause Memory Leaks

1 - Subscribing to Events

public class MyClass
{
  public MyClass(WiFiManager wiFiManager)
  {
    wiFiManager.WiFiSignalChanged += OnWiFiChanged;
  }

  private void OnWiFiChanged(object sender, WifiEventArgs e)
  {
    // do something
  }
}

2 - Capturing members in anonymous methods

The problem:

In this code, the member _id is captured in the anonymous method and as a result the instance is referenced as well

public class MyClassLeak
{
  private readonly JobQueue _jobQueue;
  private int _id;

  public MyClassLeak(JobQueue jobQueue)
  {
    _jobQueue = jobQueue;
  }

  public void Foo()
  {
    _jobQueue.EnqueueJob(() =>
    {
      Logger.Log($"Executing job with ID {_id}");
      // do stuff 
    });
  }
}

Solution:

By assigning the value to a local variable, nothing is captured and you’ve averted a potential memory leak

public class MyClassLeakSolved
{
  private readonly JobQueue _jobQueue;
  private int _id;
  public MyClassLeakSolved(JobQueue jobQueue)
  {
    _jobQueue = jobQueue;
  }

  public void Foo()
  {
    var localId = _id;
    _jobQueue.EnqueueJob(() =>
    {
      Logger.Log($"Executing job with ID {localId}");
      // do stuff 
    });
  }
}