CODEWITHSUNDEEP
c#aspnetboilerplate
Yunhai
Yunhai

Reputation: 91

This MySqlConnection is already in use

I created an RecurringJob with Hangfire, but when the job is finish I'm getting the following ERROR:

ERROR 2018-12-05 15:20:05,982 [fc937] Hangfire.AutomaticRetryAttribute - Failed to process the job '81': an exception occurred.
System.InvalidOperationException: This MySqlConnection is already in use.   See https://fl.vu/mysql-conn-reuse
at MySqlConnector.Core.ServerSession.StartQuerying(MySqlCommand command) in    C:\projects\mysqlconnector\src\MySqlConnector\Core\ServerSession.cs:line 149
at MySqlConnector.Core.TextCommandExecutor.ExecuteReaderAsync(String commandText, MySqlParameterCollection parameterCollection, CommandBehavior  behavior, IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\Core\TextCommandExecutor.cs:line 33
at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQueryAsync(IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlCommand.cs:line 261
at MySql.Data.MySqlClient.MySqlTransaction.CommitAsync(IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlTransaction.cs:line 25
at MySql.Data.MySqlClient.MySqlTransaction.Commit() in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlTransaction.cs:line 12
at Microsoft.EntityFrameworkCore.Storage.RelationalTransaction.Commit()
at Abp.EntityFrameworkCore.Uow.DbContextEfCoreTransactionStrategy.Commit() in D:\Github\aspnetboilerplate\src\Abp.EntityFrameworkCore\EntityFrameworkCore\Uow\DbContextEfCoreTransactionStrategy.cs:line 66
at Abp.EntityFrameworkCore.Uow.EfCoreUnitOfWork.CommitTransaction() in D:\Github\aspnetboilerplate\src\Abp.EntityFrameworkCore\EntityFrameworkCore\Uow\EfCoreUnitOfWork.cs:line 92
at Abp.Domain.Uow.UnitOfWorkBase.Complete() in D:\Github\aspnetboilerplate\src\Abp\Domain\Uow\UnitOfWorkBase.cs:line 256
at Abp.Domain.Uow.UnitOfWorkInterceptor.PerformSyncUow(IInvocation invocation, UnitOfWorkOptions options) in D:\Github\aspnetboilerplate\src\Abp\Domain\Uow\UnitOfWorkInterceptor.cs:line 68
at Castle.DynamicProxy.AbstractInvocation.Proceed()

the code like this:

public class TestJob : ITransientDependency
{
    private readonly IDapperRepository<Customer> _customerDapperRepository;
    private readonly IRepository<Customer> _customerRepository;
    private readonly IRepository<User, long> _userRepository;
    public TestJob(...)
    {
     ...
    }
    [UnitOfWork]
    [AutomaticRetry(Attempts = 0)]
    public virtual void ExecuteJob()
    {
       var someCustomerList = GetSomeCustomerList();
       foreach (var customer in someCustomerList )
       {
          //do some db operations
       }
    }
    private List<Customer> GetSomeCustomerList()
    {
       //get some Customer with conditions
    }
}

The code above does not report an error during debugging,I'm confused what's wrong.

Upvotes: 9

Views: 20564

Answers (4)

Consule
Consule

Reputation: 1259

Im my case I just changed AddScoped to AddTransient

e.g

services.AddScoped<DbSession>();

To

services.AddTransient<DbSession>();

Upvotes: 0

Niels Schmidt
Niels Schmidt

Reputation: 411

If you are using Entity Framework and creating a new query using a property from a list of items that has not been resolved yet, then you can get this error.

What fixed it for me was simply adding .ToList() before using the property :)

In your case it would be:

var someCustomerList = GetSomeCustomerList().ToList() //adding ToList will resolve it;
       foreach (var customer in someCustomerList )
       {
          //do some db operations
       }```

Upvotes: 7

fhcimolin
fhcimolin

Reputation: 614

Although i'm not entirely sure of what's happening, consider doing the following:

  • Closing the connection each time you use it;
  • Consider doing all of your database operations inside a using scope. This way, each time you query your database, the connection instance is properly disposed, without you having to bother about closing it.

Upvotes: -1

Anderson Paiva
Anderson Paiva

Reputation: 978

If you are using asynchronous programming as was my case, make sure that in your flow you are not doing a round trip to DB using async Task and a new asynchronous round trip to DB without use Task, when I noticed and I changed my code, it was fixed

Upvotes: 6

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