多线程执行DbContext

A second operation was started on this context before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913

问题出现场景

多线程操作EFCore 获取数据库上下文姿势不对；以下是正确姿势！

需求

使用 ef core v5.0.9 对数据库表新增数据。

多线程操作EFCore

步骤1：设置程序线程池最大化

public static void Main(string[] args)
{
    int maxWorkerThreads, maxIoThreads;
    ThreadPool.GetMaxThreads(out maxWorkerThreads, out maxIoThreads);

    CreateHostBuilder(args).Build().Run();
}

有利于程序中线程创建速度加快。

步骤2：OrderingContext 数据上下文注入为瞬时

public void ConfigureServices(IServiceCollection services)
        services.AddDbContext<OrderingContext>(options =>
            {
                if (Startup.EfLoggerFactory != null)
                    options.UseLoggerFactory(Startup.EfLoggerFactory);
                options.UseSqlServer(configuration["OrderCommandDBConfig:ConnectionString"]);//, builder => builder.EnableRetryOnFailure()
            },
            ServiceLifetime.Transient,
            ServiceLifetime.Transient
            ).AddUnitOfWork<OrderingContext>();

注入DbContext声明周期为， ServiceLifetime.Transient ， 其他Ioc容器也设置为这个瞬时状态；

步骤3：仓储注入IServiceProvider

public class OrderRepository : Repository<Order, OrderingContext>, IOrderRepository
{
    private IServiceProvider _serviceProvider;


    public OrderRepository(OrderingContext context, IServiceProvider serviceProvider) : base(context)
    {
        _serviceProvider = serviceProvider;
    }

业务代码调用数据库上下文， 从_serviceProvider获取数据库上下文实例

using (var ct = _serviceProvider.GetService<OrderingContext>())
{
	...业务代码...
}