In this article, we will analyze the causes of memory leaks and high CPU consumption in ASP.NET Core applications, explore debugging techniques, and provide best practices to optimize resource utilization for scalable and efficient web applications.

Understanding Memory Leaks and High CPU Usage in ASP.NET Core

Memory and CPU inefficiencies in ASP.NET Core can arise from poor object lifecycle management, inefficient queries, or excessive background tasks. Common causes include:

• Improperly scoped dependency injection leading to memory retention.
• Blocking synchronous calls inside asynchronous methods.
• Unoptimized middleware executing unnecessary operations per request.
• Long-running background tasks consuming excessive CPU cycles.
• Unclosed database connections leading to resource exhaustion.

Common Symptoms

• Gradual increase in memory usage without dropping, leading to out-of-memory errors.
• High CPU consumption during peak loads despite low request traffic.
• Slow API response times and timeouts under heavy load.
• Application crashes with System.OutOfMemoryException.
• Unexpected GC (Garbage Collection) behavior affecting performance.

Diagnosing Memory Leaks and High CPU Usage in ASP.NET Core

1. Monitoring Memory Consumption

Use dotnet counters to track memory usage:

dotnet-counters monitor --counters System.Runtime MyApp

2. Identifying Inefficient Middleware

Log middleware execution times to detect performance bottlenecks:

app.Use(async (context, next) => {
    var stopwatch = Stopwatch.StartNew();
    await next.Invoke();
    stopwatch.Stop();
    Console.WriteLine($"Middleware executed in {stopwatch.ElapsedMilliseconds}ms");
});

3. Detecting Unoptimized Dependency Injection

Check for singleton services holding stateful data unintentionally:

services.AddSingleton<IUserRepository, UserRepository>(); // Potential memory leak if not stateless

4. Profiling CPU Usage

Use PerfView to analyze high CPU-consuming threads:

PerfView collect

5. Tracking Unclosed Database Connections

Ensure proper connection disposal in Entity Framework Core:

using (var context = new MyDbContext()) {
    var users = await context.Users.ToListAsync();
}

Fixing Memory Leaks and High CPU Usage in ASP.NET Core

Solution 1: Managing Dependency Injection Lifetimes Properly

Use scoped services where necessary to avoid memory retention:

services.AddScoped<IUserRepository, UserRepository>();

Solution 2: Avoiding Synchronous Blocking Calls

Use async/await instead of blocking operations:

public async Task<User> GetUserAsync(int id) {
    return await _dbContext.Users.FindAsync(id);
}

Solution 3: Optimizing Middleware Execution

Short-circuit unnecessary middleware for better efficiency:

if (!context.Request.Path.StartsWithSegments("/api")) {
    await next.Invoke();
}

Solution 4: Managing Long-Running Background Tasks Efficiently

Use Hosted Services instead of blocking requests:

public class MyBackgroundService : BackgroundService {
    protected override async Task ExecuteAsync(CancellationToken stoppingToken) {
        while (!stoppingToken.IsCancellationRequested) {
            await Task.Delay(5000, stoppingToken);
        }
    }
}

Solution 5: Ensuring Proper Database Connection Handling

Use DbContextFactory for short-lived database contexts:

services.AddDbContextFactory<MyDbContext>();

Best Practices for Efficient ASP.NET Core Applications

• Use scoped dependency injection for services that require database access.
• Avoid blocking async calls with .Result or .Wait().
• Optimize middleware execution by short-circuiting unnecessary logic.
• Monitor application performance using tools like dotnet-counters and PerfView.
• Ensure database connections are properly disposed to prevent resource leaks.

Conclusion

Memory leaks and high CPU usage in ASP.NET Core applications can severely impact performance and scalability. By optimizing dependency injection, improving async handling, and managing middleware execution efficiently, developers can ensure robust and high-performance applications.

FAQ

1. Why is my ASP.NET Core application consuming excessive memory?

Improper dependency injection lifetimes, unoptimized middleware, and unclosed database connections can lead to memory leaks.

2. How do I debug high CPU usage in ASP.NET Core?

Use dotnet-counters and PerfView to analyze CPU-consuming processes.

3. What is the best way to prevent memory leaks in ASP.NET Core?

Use scoped services where necessary, ensure proper database connection disposal, and avoid retaining unnecessary state in singletons.

4. Can blocking async calls cause high CPU usage?

Yes, using .Result or .Wait() on async methods can lead to thread starvation and high CPU consumption.

5. How do I optimize middleware performance in ASP.NET Core?

Short-circuit unnecessary middleware execution and ensure that middleware only runs for relevant request paths.