connection.BeginTransaction cause memory leak

[wzl-bxg]

Hello, when using connection.BeginTransaction, the below code will cause memory leak:

public static ICapTransaction BeginTransaction(this IDbConnection dbConnection, ICapPublisher publisher, bool autoCommit = false)
{
    if (dbConnection.State == ConnectionState.Closed)
    {
        dbConnection.Open();
    }

    var dbTransaction = dbConnection.BeginTransaction();
    publisher.Transaction.Value = publisher.ServiceProvider.GetService<ICapTransaction>();
    return publisher.Transaction.Value.Begin(dbTransaction, autoCommit);
}

ICapPublisher is registered as singleton, ICapTransaction is registered as transient; you create transient object(ICapTransaction) by singleton object(ServiceProvider), and the transient object(ICapTransaction) implements IDisposable, so the transient object(ICapTransaction) will never GC because the IOC container is not released.

I simulate 100000+ calls to the action AdonetWithTransaction, see the below code:

[Route("~/adonet/transaction")]
public IActionResult AdonetWithTransaction()
{
using (var connection = new MySqlConnection(AppDbContext.ConnectionString))
{
    using (var transaction = connection.BeginTransaction(_capBus, true))
    {
        //your business code
    }
}

return Ok();
}

Then I turn on VS diagnostics tools to monitor memory changes, I found the objects that inherit ICapTransaction will persist in memory,see below:

You can use ActivatorUtilities.GetServiceOrCreateInstance to create transient object(ICapTransaction) in method connection.BeginTransaction

[xiangxiren]

Cannot use ActivatorUtilities.GetServiceOrCreateInstance, it still gets an instance from IServiceProvider first. Should use ActivatorUtilities.CreateInstance(provider, type)

[yang-xiaodong]

Hello,

This is indeed a bug, we haven't found it for a long time, thank you for your feedback and suggestions

[yang-xiaodong]

I re-tested the fixed code and it looks good

root@yxd-server03:~# wrk -c 200 -t 4 -d 15 http://192.168.2.2:5000/adonet/transaction
Running 15s test @ http://192.168.2.2:5000/adonet/transaction
  4 threads and 200 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency   182.72ms  153.25ms   1.80s    89.43%
    Req/Sec   282.62    207.65     0.87k    61.99%
  9542 requests in 15.06s, 857.29KB read
  Socket errors: connect 0, read 0, write 0, timeout 200
Requests/sec:    633.63
Transfer/sec:     56.93K

  [Route("~/adonet/transaction")]
  public IActionResult AdonetWithTransaction()
  {
      using (var connection = new SqlConnection(AppDbContext.ConnectionString))
      {
          using (var transaction = connection.BeginTransaction(_capBus, true))
          {
              //your business code
              connection.Execute("insert into test(name) values('test')", transaction: transaction);

              _capBus.Publish("sample.rabbitmq.sqlserver", new Person()
              {
                  Id = 123,
                  Name = "Bar"
              });


              transaction.Dispose();
          }

      }

      return Ok();
  }

[yang-xiaodong]

Issue was fixed in 5.0.1 and released to NuGet a few minutes ago

[maulik-modi]

@wzl-bxg , what tool did you use here?