.Net 7 WinForms - process hangs after closing the app SOLVED

[zarkogajic]

Hi Support,

Can you shed some light on the following:

Attached are two super simple same WinForms applications using AxPXV_Control:

"DotNetFrameworkWinFormsSimple.zip" using ".NET Framework 4.8.9181.0"

DotNetFrameworkWinFormsSimple.zip

(10.64 KiB) Downloaded 5 times

"DotNetWinFormsSimple.zip" using ".NET 7.0.12".

DotNetWinFormsSimple.zip

(5.48 KiB) Downloaded 5 times

As you can see in (main) Form1's constructor I'm manually calling PXV_Inst.Init() and PXV_Inst.Shutdown() in both apps.

In the case of ".Net 7.x" - after closing the main form - the process is kept in memory and never actually terminates.

The same happens even if I do *not* manually call Init()/Shutdown() - but let the AxPXV_Control do the Init/Shutdown thingie.

In case of ".NET Framework 4.x" - all works as expected - the app closes and the process is also terminated.

The following is a kind of a workaround, for .Net 7, but does not smell nice

Code: Select all

// Workaround for process hang issue detected on PDFX version 10.0.1.380 / .Net 7
while (PxvInst.State != (int)PXV_InstStateFlags.PXV_InstState_ShutDown)
{
  PxvInst.Shutdown();
}

Is this a bug or expected or ?

-žarko

[Vasyl-Tracker Dev Team]

Hi Zarko.

We investigated it and found that under Net7 our ActiveX control doesn't receive the destroy-event from the system when the system destroys the control's window. Which is quite strange and critical for the control because it finalizes itself at this event. In the new upcoming build we added the workaround for this case, and it seems it works better now. Also, the second part of the fix needs to be done in your code too. You need to release (set to *null*) all used references to sdk-objects before cleaning the GC. I.e., instead of this:

Code: Select all

private readonly PXV_Inst pxvInst = new();

public Form1()
{
      pxvInst.Init();
      ....
}

private void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
      pxvInst.Shutdown(); 
      GC.Collect();
      GC.WaitForPendingFinalizers();
}

is better to use this way:

Code: Select all

private PXV_Inst pxvInst;

public Form1()
{
      pxvInst = new();
      pxvInst.Init();
      ....
}

private void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
      pxvInst.Shutdown(); 
      pxvInst = null; // important(!) to do it here
      GC.Collect();
      GC.WaitForPendingFinalizers();
}

HTH.

[zarkogajic]

Hi Vasyl,

Great, thanks!

ž

[Dimitar - Tracker Supp]