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NET Memory Management Two Effective Ways to Free Resources

Popularity：831 ℃/2024-10-14 11:00:31

preamble

Hi everyone! Today we're going to talk about memory management in .NET. NET. NET has a great garbage collection system to automatically clean up objects that are no longer in use, but in some cases we need to take matters into our own hands to free up some special resources, such as open files or database connections. Failure to do so may cause the program to run poorly or even crash. In this article, we will introduce two simple and effective ways to manage these resources: using statements and explicitly calling the Dispose method. These two methods allow us to control the lifecycle of resources more effectively, avoid memory leaks and other problems, and ensure the robustness of the application. Whether you're just starting out or you're a technical expert, I hope you've learned some useful tips and tricks from this article that will help us make our programs run more reliably and steadily.

main body (of a book)

Memory management in .NET relies heavily on the garbage collection mechanism, which mainly refers to memory management and the release of unmanaged resources. However, there are times when we may need finer-grained control over the release of certain resources. There are two main ways to handle this
  • Garbage Collection (GC)
  • Confirmatory Resource Release (DRD)
Official Documents/zh-cn/dotnet/standard/managed-code

Garbage Collection

Garbage collection is a very important automatic memory management mechanism in . It helps us to automatically clean up objects that are no longer in use and free up the memory occupied by these objects, avoiding the tedious task of managing memory manually and allowing us to focus more on writing business logic.

1. Why do we need garbage collection?

  • Avoid memory leaks: Garbage collection automatically detects objects that are no longer in use and frees the memory space they occupy.
  • Simplified code: no need to manually free memory, reducing errors and burdens in the code.

2. What are the characteristics of waste recycling?

  • Runs automatically and does not need to be explicitly called by the developer
  • Triggered when out of memory
  • Free managed memory (i.e., memory allocated through the .NET inner village)
  • Memory is not guaranteed to be freed immediately, but rather periodically, depending on memory pressures

3. What are the limitations of garbage collection?

  • Unable to handle unmanaged resources such as file handles, database links, Graphics Device Interface (GDI) objects, etc.
  • May cause the application to pause briefly (GC pause)

4. What do I need to pay attention to for garbage collection?

  • Try to avoid large object heaps: large objects will be allocated directly to large object heaps, which may cause the garbage collector to work more frequently.
  • Calling () at the right time: Although in most cases it is not necessary to manually trigger garbage collection, in some special scenarios, such as long-running applications, you can consider calling () at the right time to help reclaim memory.

Deterministic resource release

For unmanaged resources .NET provides a deterministic resource release mechanism, usually implemented through the IDisposable interface.

1. Use the using statement

NET provides the IDisposable interface to help manage unmanaged resources (such as file handles, database connections, etc.).

Use the using statement to automatically free resources held by objects that implement IDsposable. Using the using statement ensures that resources are freed correctly even if an exception occurs.

The StreamReader in the example implements the IDsposable interface.

By using the using statement, the Dispose method is automatically called when the StreamReader object is out of scope, freeing the file handle.

using System;
using ;
class Program
{
    static void Main()
    {
        using (var stream = new FileStream("", ))
        {
            byte[] buffer = new byte[1024];
            int bytesRead = (buffer, 0, );
            // Processing of read data
        }
        // The file stream is automatically closed
     }
}

2. Explicitly call the Dispose method.

If you can't use a using statement (for example, in a loop or other complex situation), you can manually call the Dispose method to free the resource. When an object implements the IDsposable interface, meaning that it holds resources that need to be freed manually, objects that implement IDsposable must override the Dispose method to clean up the unmanaged cache.

using System;
using ;
class Program
{
    static void Main()
    {
        FileStream stream = new FileStream("", );
        try
        {
            byte[] buffer = new byte[1024];
            int bytesRead = (buffer, 0, );
            // Processing of read data
        }
        finally
        {
            ();
        }
     }
}

summarize

Well, today we talked about memory management in . By using using statements and explicitly calling the Dispose method, we can better control those special resources like files and database connections. This not only prevents program errors, but also makes our programs run smoother.

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