⚡ Connection Pooling and Performance Tuning in .NET Core

📖 What is Connection Pooling?

Connection Pooling is a technique where database connections are reused instead of being created and destroyed for each request. This reduces overhead and improves performance in high-traffic applications.

🛠 Example in .NET Core (SQL Server)

Connection pooling is enabled by default in ADO.NET and EF Core. You can configure it in the connection string:

"ConnectionStrings": {
  "DefaultConnection": 
    "Server=.;Database=ShopDb;Trusted_Connection=True;
     Max Pool Size=100;Min Pool Size=5;Connect Timeout=30;"
}
    

• Max Pool Size: Maximum number of connections in the pool.
• Min Pool Size: Minimum number of connections kept alive.
• Connect Timeout: Time to wait before failing a connection attempt.

🛠 EF Core Performance Tuning Techniques

• DbContext Pooling: Reuse DbContext instances with services.AddDbContextPool<AppDbContext>().
• AsNoTracking(): Use for read-only queries to avoid change tracking overhead.
• Compiled Queries: Cache query execution plans for repeated queries.
• Batching: EF Core automatically batches multiple INSERT/UPDATE statements.
• Indexes: Ensure proper indexing in the database for frequently queried columns.
• Projection: Select only required fields instead of entire entities.

✅ Advantages

• Reduces connection creation overhead.
• Improves scalability under high load.
• Optimizes resource utilization.
• EF Core pooling reduces memory allocations.

⚠️ Disadvantages

• Poorly tuned pool sizes can cause bottlenecks.
• Idle connections may consume resources unnecessarily.
• Long-running queries can block pooled connections.

🧭 Best Practices

• Use DbContext pooling for high-throughput apps.
• Set Max Pool Size based on workload and DB server capacity.
• Dispose DbContext and connections properly (using or DI scope).
• Use AsNoTracking() for queries that don’t modify data.
• Profile queries with logging and Application Insights.

🔒 Precautions

• Monitor connection pool usage with performance counters.
• Avoid connection leaks — always close/dispose connections.
• Be cautious with parallel queries; they may exhaust the pool.
• Secure connection strings (Azure Key Vault, user secrets).

🎯 Summary

Connection pooling and performance tuning are essential for building scalable .NET Core applications. Use EF Core features like DbContext pooling, AsNoTracking, compiled queries, and batching along with proper database indexing and monitoring to achieve optimal performance.