CODEWITHSUNDEEP
c#memoryformclosing
Tin Chip
Tin Chip

Reputation: 135

Why does memory increase after closing a form?

I'm kinda new to C#. I read that closing a form instead of hiding can free memory. However, when I closed a form, it even made memory increases. To be specific, I have two form: Form1 and Form2. When I log in user successfully, Form2 will open (Memory is 20Mb). Form2 have a button to log out user, close it and turn back to Form1 (Memory now increases to 41Mb and continue increasing for the next user). I don't know why, is there anybody can help me? This is my code to close Form2:

private void doctorLogoutBtn_Click(object sender, EventArgs e)
{
    imgBox.Image.Dispose();
    this.Dispose();
    Form1 Login = new Form1();
    Login.Show();
    this.Close();   
}

Upvotes: 0

Views: 291

Answers (2)

Dmitrii Bychenko
Dmitrii Bychenko

Reputation: 186678

It should be something like this:

using System.Linq;

...

private void doctorLogoutBtn_Click(object sender, EventArgs e)
{
    // Free image resources (may appear to be optional, but doesn't spoil anything) 
    imgBox.Image.Dispose();

    // Do we have any Form1 instances?
    Form1 Login = Application
      .OpenForms
      .OfType<Form1>()
      .LastOrDefault(); // If we have several Form1's, let's take the last one

    // Only when we haven't any Form1 instances we have to create a new one
    if (null == Login) 
      Login = new Form1(); 

    Login.Show();

    // Close (and Dispose) 
    this.Close();   
}

In your current code

...
Form1 Login = new Form1();
Login.Show();
...

you are creating yet another Form1 instance while not looking for alreday created ones.

Upvotes: 1

Paweł Łukasik
Paweł Łukasik

Reputation: 4153

Well from your description you want to go back to Form1 that was already created but what I can see from this short piece of code you create a new Form.

Form1 Login = new Form1();

Is the old Form1 released when you are displaying Form2? Maybe the old one is not properly released? The discolosed part fo code doesn't tell that.

it's too little code that you show to be sure but you can run a Memory profiler (dotMemory, ANTS Memory) and check if there are some objects left that should not be.

Upvotes: 1

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