Coding Bolt

In Entity Framework Core (EF Core), thread-safety checks are built-in diagnostics to warn developers when they’re using DbContext instances in a potentially unsafe multi-threaded manner. Using a DbContext across multiple threads can lead to unpredictable results and hard-to-debug issues.

However, in some scenarios, a developer might be certain that their usage is safe and wants to disable these checks to improve performance or to eliminate warnings. This is where EnableThreadSafetyChecks(false) comes into play.

1. Understanding the Need for Thread Safety Checks: EF Core’s DbContext is not thread-safe. Using it concurrently can lead to unexpected behaviors, including data corruption, race conditions, or exceptions. To assist developers in identifying and avoiding such pitfalls, EF Core comes with built-in thread-safety diagnostics.

2. Disabling Thread Safety Checks: If a developer is certain that their usage of DbContext in multi-threaded scenarios is safe, or they have implemented their own synchronization mechanisms, they might want to disable these built-in checks.

Let’s see an example and some benchmark results:

public class BlogContext : DbContext
{
    public DbSet<Blog> Blogs { get; set; }
    public DbSet<Post> Posts { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer(@"Server=.;Database=BlogDB;Trusted_Connection=True;TrustServerCertificate=True");
    }
}

public class BlogThreadContext : DbContext
{
    public DbSet<Blog> Blogs { get; set; }
    public DbSet<Post> Posts { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.EnableThreadSafetyChecks(false);
        optionsBuilder.UseSqlServer(@"Server=.;Database=BlogDB;Trusted_Connection=True;TrustServerCertificate=True");
    }
}

[MemoryDiagnoser]
public class ThreadSafetyDisabledVsNormal
{
    private readonly BlogContext _context;
    private readonly BlogThreadContext _threadContext;

    public ThreadSafetyDisabledVsNormal()
    {
        _context = new BlogContext();
        _threadContext = new BlogThreadContext();
    }

    [Benchmark]
    public async Task<Blog> GetBlogsAsync()
    {
        return await _context.Blogs.AsNoTracking().FirstOrDefaultAsync(b => b.BlogId == 4000);
    }

    [Benchmark]
    public async Task<Blog> GetBlogsNoChecksAsync()
    {
        return await _threadContext.Blogs.AsNoTracking().FirstOrDefaultAsync(b => b.BlogId == 4000);
    }
}

• Always be certain of thread safety when turning off diagnostics. The safety of your data and operations should always be a priority.
• Disabling these checks doesn’t make DbContext thread-safe. It simply stops EF Core from notifying you about potential issues.
• Regularly review your code and ensure that newer parts of your application adhere to the necessary safety standards.

Conclusion

Entity Framework Core offers various tools and diagnostics to aid developers in creating stable, data-driven applications. While EnableThreadSafetyChecks provides a way to turn off specific diagnostics, it should be used judiciously. Being informed and cautious is the best way to leverage this option without compromising application stability.