MySQL Bugs: #84791: Memory leak in Connector/Net

Bug #84791	Memory leak in Connector/Net
Submitted:	2 Feb 2017 9:25	Modified:	30 Mar 2017 7:44
Reporter:	Antonis Pa	Email Updates:
Status:	Can't repeat	Impact on me:	None
Category:	Connector / NET	Severity:	S1 (Critical)
Version:	6.9.9	OS:	Windows
Assigned to:		CPU Architecture:	Any
Tags:	memory leak

Description:
I have a database with a table that contains 1,200,000 rows and about 30 columns. I use MySql.Data and MySql.Data.Entity  to read data from this table. 
More specific I have use 10 tasks to read the entire table. I can see that my memory increases to 3GB+ which us insanely crazy without dropping even though when the reading finishes.

How to repeat:
This is my code

 public void MultiThreading()
        {
            try
            {
                IEnumerable<IEnumerable<int>> splittedLists = ...

                Task[] listOfTasks = new Task[10];
                foreach (var listOfUsers in splittedLists)
                {
                    Task tsk = new Task(() => GetProducts(listOfProducts.ToList()));
                    listOfTasks[count] = tsk;
                    tsk.Start();
                }

                Task.WaitAll(listOfTasks);

            }
            catch (Exception ex)
            {

            }
        }

        public void GetProducts(List<int> listOfProducts)
        {
            using (MySqlConnection connection = new MySqlConnection(connectionString))
            {
                try
                {
                    using (MT4DbContext context = new MT4DbContext(connection, false))
                    {
                        connection.Open();

                        foreach (var product in listOfProducts)
                        {
                            var products = (from prod in context.Products
                                              where prod.Id == product.Id
                                              select prod).ToList();
                        }
                    }

                }
                catch (Exception ex)
                {

                }
            }
        }

As per my mem profiler I can see that these objects get a lot of memory

Type, Objects count, Bytes, Minimum retained bytes
System.Data.Entity.Core.Objects.EntityEntry, 695673, 72349992, 1291162080
System.Data.Entity.Core.Objects.Internal.EntityWrapperWithoutRelationships<Products>, 695673, 61219224, 172526904
System.Data.Entity.Core.EntityKey, 695675, 50088600, 66784980
System.Data.Entity.Core.Objects.DataClasses.RelationshipManager, 695673, 44523072, 77915376
System.Collections.Generic.List<StateManagerValue>, 695672, 27826880, 1046286536

The largest object type is this

Nodes from "All objects in the snapshot"

Type, Objects count, Bytes, Minimum retained bytes
System.Data.Entity.Core.Objects.StateManagerValue[], 695675, 550970760, 1018460496

This is a screenshot of my mem profiler

Attachment: memleak.PNG (image/png, text), 15.80 KiB.

Hello  Antonis,

Thank you for the bug report.
I could not repeat the issue at our end using with Visual Studio 2013, Connector/NET 6.9.9 with .net core and EF Core.
Could you please provide repeatable test case (exact steps/sample project, screenshot etc. - please make it as private if you prefer) to confirm this issue at our end?

Thanks,
Chiranjeevi.

Unfortunately I cannot provide sample as this is part of a huge enterprise project.

I am using VS2015, I am using

<packages>
  <package id="EntityFramework" version="6.0.0" targetFramework="net46" />
  <package id="MySql.Data" version="6.9.9" targetFramework="net46" />
  <package id="MySql.Data.Entity" version="6.9.9" targetFramework="net46" />
</packages>

Try to run the read process with the code that I attached in my first comment with multiple threads.

Thanks

Hello  Antonis,

Thank you for the bug report.
I could not repeat the issue at our end using with Visual Studio 2015, Connector/NET 6.9.9.
If you can provide more information, feel free to add it to this bug and change the status back to 'Open'.

Thank you for your interest in MySQL.

Thanks,
Chiranjeevi.