Handling SQL Server Deadlocks When Using Parallel Transactions with EF Core 6
I'm trying to configure I'm currently developing an ASP.NET Core application using Entity Framework Core 6, and I'm encountering deadlock issues when multiple parallel transactions are being executed. The application has a scenario where several users can submit orders simultaneously, which leads to deadlocks on the 'Orders' table when trying to update inventory stock. I've implemented a simplified version of the order processing code as follows: ```csharp public async Task ProcessOrderAsync(Order order) { using (var transaction = await _context.Database.BeginTransactionAsync()) { try { var product = await _context.Products.FindAsync(order.ProductId); if (product.Quantity < order.Quantity) { throw new InvalidOperationException("Not enough stock available."); } product.Quantity -= order.Quantity; await _context.SaveChangesAsync(); // Other processing logic await transaction.CommitAsync(); } catch (DbUpdateConcurrencyException ex) { // Log or handle concurrency exception await transaction.RollbackAsync(); throw; } catch (Exception ex) { // Log the exception await transaction.RollbackAsync(); throw; } } } ``` Despite using transactions, deadlocks occur frequently, especially under load. The SQL Server error log shows messages like, "Transaction (Process ID 123) was deadlocked on lock resources with another process and has been chosen as the deadlock victim." I've tried adding retries for the transaction logic, but that doesn't seem to resolve the underlying deadlock situation. I've also enabled trace flags 1204 and 1222 to get more insight into the deadlocks occurring, and I'm seeing that the deadlocks are mostly due to conflicting updates on the same rows in the 'Products' table. What strategies can I implement to avoid these deadlocks in my EF Core application? Is it a good idea to use optimistic concurrency, or should I consider using a different approach for handling orders in parallel? Any best practices or design patterns to recommend would be greatly appreciated. For context: I'm using Csharp on macOS. What's the best practice here? For reference, this is a production application. I appreciate any insights!