每个请求的dbContext aspboilerplate [英] DbContext per request aspboilerplate

问题描述

我需要为导入文件实现多线程后台作业.我已经用后台作业(Hangfire)实现了它.但是，如果我使用一个线程，它将非常慢.函数看起来像这样.

I need to implement multithreading background job for import file. I have implemented it with background job(Hangfire). But if i use one thread it goes very slow. The function look like this.

我使用非事务处理单元将更改立即保存到db.

I using non-transaction unit to save changes to db immediately.

var contactFound = await _contactRepository.FirstOrDefaultAsync(x => x.Email.ToLower() == contact.Email.ToLower());

            if (contactFound != null)
            {
                await _bjInfoManager.AddLog(args.JobId, "Found duplicated email: " + contact.Email);

            }
            else
            {
                contact.ContactListId = args.ContactListId;
                contact.Email = contact.Email.ToLower();

                await _contactRepository.InsertAsync(contact);

                //Save changes in db
                await CurrentUnitOfWork.SaveChangesAsync();
            }

当我尝试将其与Producer-Consumer Dataflow Pattern结合使用时，会出现问题.我抛出异常在先前的异步操作完成之前，在此上下文上启动了第二个操作."

The problem occur when I tries to use this with Producer-Consumer Dataflow Pattern. I throws the exception "A second operation started on this context before a previous asynchronous operation completed."

问题是如何在此方法内创建隔离的DbContext.请帮助我.

The question is how to create isolated DbContext inside this method. Please help me.

推荐答案

事务不应该是多线程的.如果您在UOW中创建新的任务/线程，则可以在using块中使用IUnitOfWork.Begin(TransactionScopeOption.RequiresNew)创建单独的UOW.

Transactions should not be multi-threaded. If you create a new task/thread in a UOW, you can create a seperated UOW using IUnitOfWork.Begin(TransactionScopeOption.RequiresNew) in a using block.

查看链接

• https://github.com/aspnetboilerplate/aspnetboilerplate/issues/619
• 实体框架是否支持多线程?
• 实体框架和多线程

如果使用的是Microsoft SQL Server，则建议您使用批量插入.它比实体框架超级快.

If you are using Microsoft SQL Server, then I recommend you to use bulk insert. It's super fast than entity framework.

https://docs.microsoft.com/en-us/sql/t-sql/statements/bulk-insert-transact-sql

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