.net core 多线程执行数据库操作时提示 “Cannot access a disposed object“ 解决办法

• 使用.net core 默认依赖注入时，数据库上下文dbcontext大部分使用的都是 scoped service

• .net core 在执行多线程操作时，如果主线程已经结束并返回，那么dbcontext也会被释放，此时子线程仍需要访问数据库上下文时，会出现无法访问已关闭资源的错误

• 先看示例

    public class UserController : Controller
    {
        private readonly IAccountService _accountService;

        public UserController(IAccountService accountService)
        {
            _accountService = accountService;
        }
        public IActionResult Test()
        {
            Task.Factory.StartNew(() =>
            {
                var account = _accountService.GetRoleList().FirstOrDefault();
                account.Name = "foo";
                _accountService.UpdateRole(account);
            });
            return View();
        }
    }

*解决方案

    public class UserController : Controller
    {
        private readonly IAccountService _accountService;
        private readonly IServiceScopeFactory _serviceScopeFactory;

        public UserController(IAccountService accountService,
            IServiceScopeFactory serviceScopeFactory)
        {
            _accountService = accountService;
            _serviceScopeFactory = serviceScopeFactory;
        }
        public IActionResult Test()
        {
            Task.Factory.StartNew(() =>
            {
                using (var scope = _serviceScopeFactory.CreateScope())
                {
                    var newAccountService = scope.ServiceProvider.GetRequiredService<IAccountService>();
                    var account = newAccountService.GetRoleList().FirstOrDefault();
                    account.Name = "foo";
                    newAccountService.UpdateRole(account);
                }
                
            });
            return View();
        }
    }

• 参考文档 https://go.microsoft.com/fwlink/?linkid=2097913