Asp.net问题随笔： An attempt was made to use the context while it is…nce members are not guaranteed to be thread safe

用.net 5在做Vue的webapi开发的时候，一个页面调多个接口的时候就会返回这样的红色报错：An attempt was made to use the context while it is…nce members are not guaranteed to be thread safe。

查看了一下线程；两个Action使用的不一样。

//查看线程
Thread.GetCurrentProcessorId();

 

初步判断是两个接口的间隙时间太短，前一个还没完成的情况下又来一个，两个线程同时使用了EF Core的同一服务导致的不安全。

于是跟了下服务的生命周期，官方代码如下

namespace Microsoft.Extensions.DependencyInjection
{
    //
    // 摘要:
    //     Specifies the lifetime of a service in an Microsoft.Extensions.DependencyInjection.IServiceCollection.
    public enum ServiceLifetime
    {
        //
        // 摘要:
        //     Specifies that a single instance of the service will be created.
        Singleton,
        //
        // 摘要:
        //     Specifies that a new instance of the service will be created for each scope.
        //
        // 言论：
        //     In ASP.NET Core applications a scope is created around each server request.
        Scoped,
        //
        // 摘要:
        //     Specifies that a new instance of the service will be created every time it is
        //     requested.
        Transient
    }
}

 

 

解决方法是将之前Startup里用的

ServiceLifetime.Scoped 换成 ServiceLifetime.Transient;每次请求时，都创建一个服务的新实例。这样就不会冲突了。代码如下：

services.AddDbContext<MySqlDbContext>(options => options.UseMySql(connection).UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking), ServiceLifetime.Transient);
services.AddTransient<IRepositoryBase, RepositoryBase>();