Advanced C# Tips: Reuse Objects Where Possible

Reusing objects in C# is a strategy that aligns with the principles of efficient memory management and application performance optimization. This concept is important in environments where memory resources are limited or when the cost of object creation is high. For instance mobile applications, embedded systems, or server applications handling multiple concurrent requests count as typical examples.

The underlying technical reason for object reuse is to reduce the overhead related to the memory allocation and garbage collection. Every time an object is created, the .NET runtime needs to allocate space on the managed heap. As objects accumulate, the garbage collector must work harder to clean up unreferenced objects, which can lead to performance hits during collection cycles. Reusing objects can mitigate these issues by maintaining a stable number of objects, thus reducing the frequency and impact of garbage collection.

In applications where objects are created and discarded frequently, object pooling is a common technique but bare in mind that it is not the only one. This involves maintaining a “pool” of pre-instantiated objects that can be recycled and reused, rather than creating new instances each time. In C# we have object pool which provides a pool of reusable objects. See Microsoft’s official documentation for the details of ObjectPool here. Let’s give a simple example below:

var customerPool = new ObjectPool<Customer>(() => new Customer());

foreach (var data in dataList)
{
    Customer customer = customerPool.Get(); 
    customer.Name = data.Name;
    customer.Age = data.Age;
    customerPool.Return(customer); 
}

In this example, instead of allocating a new Customer object for each iteration, the application retrieves an object from the pool and then returns it to the pool when done, ready to be reused.

Object reuse not only wisely uses memory but can also contribute to reducing latency in real-time applications where the delay caused by garbage collection can lead to issues. By maintaining a steady state of memory usage and minimizing pressure on the garbage collector, applications can achieve more predictable performance.

Studies and tests, such as those performed in high-load server benchmarks or real-time application profiling, consistently demonstrate the benefits of object reuse. The results often show reductions in memory usage, improvements in response times, and lower CPU usage due to reduced garbage collection activity.

Reusing the HttpClient object in .NET applications is a practical strategy for optimizing resource management and improving application performance. It is efficient especially when handling multiple concurrent requests is common. Creating a new HttpClient instance for every request can cause resource exhaustion and socket exhaustion due to the high cost of TCP connections and DNS lookups. By reusing a single HttpClient instance, you can mitigate these issues, reduce latency, and avoid performance degradation caused by frequent garbage collection cycles.

When an HttpClient object is reused, it maintains an open connection pool, which allows for the efficient reuse of TCP connections. This minimizes the overhead of establishing new connections and ensures that resources are utilized effectively. Here’s a practical example of reusing an HttpClient object:

public class HttpClientService
{
    private static readonly HttpClient _httpClient = new HttpClient();

    public async Task<string> GetApiResponseAsync(string requestUri)
    {
        HttpResponseMessage response = await _httpClient.GetAsync(requestUri);
        response.EnsureSuccessStatusCode();
        return await response.Content.ReadAsStringAsync();
    }
}

In this example, the HttpClient instance is created once as a static readonly field, which ensures that it is reused for all HTTP requests made by the HttpClientService. This approach leverages the benefits of connection pooling and avoids the overhead of creating and disposing of HttpClient instances repeatedly.

Object reuse can be particularly beneficial in several areas in a project:

• Database Connections
• HTTP Requests
• File Handles
• Buffers and Streams
• User Sessions
• Thread Pools
• Data Caches
• Configuration Objects
• Security Tokens
• Templates and Components
• Graphic Objects
• Message Queues
• Event Handlers
• Data Transfer Objects (DTOs)

These additional areas highlight the broad applicability of object reuse strategies across different aspects of software development to optimize resource management and application performance.

Suleyman Cabir Ataman, PhD

Sharing on social media: