Excel hangs at exit after running RDVBA tests

user_17472988 0
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The following example contains three VBA modules: two classes and one regular. After I run RubberDuck VBA tests and then try to close Excel, Excel hangs while actively using the CPU. Running the tests once does not reproduce this issue every time, but when I do at least two runs, it seems that the issue is reproduced every time.

RDVBA Version 2.5.2.5871
OS: Microsoft Windows NT 6.2.9200.0, x64

Test environment 1:
Host Product: Microsoft Office XP x86
Host Version: 10.0.6501
Host Executable: EXCEL.EXE

Test environment 2:
Host Product: Microsoft Office 2016 x64
Host Version: 16.0.4266.1001
Host Executable: EXCEL.EXE

ModuleTests.bas

'@TestModule
Option Explicit
Option Private Module

Private Assert As Rubberduck.PermissiveAssertClass

#Const USE_ASSERT_OBJECT = True

'@ModuleInitialize
Private Sub ModuleInitialize()
    Set Assert = New Rubberduck.PermissiveAssertClass
End Sub

'@ModuleCleanup
Private Sub ModuleCleanup()
    Set Assert = Nothing
    Debug.Print CStr(Timer()) & ": Assert = Nothing"
End Sub

'@TestMethod("Factory")
Private Sub ztcCreate_VerifiesDefaultManager()
    Dim dbm As Class2
    Set dbm = Class2.Create(ThisWorkbook.Path)
    #If USE_ASSERT_OBJECT Then
        Assert.IsNotNothing dbm
    #Else
        Assert.IsTrue Not dbm Is Nothing
    #End If
End Sub

Class1.cls

'@PredeclaredId
Option Explicit

Public Function Create(Optional ByVal DefaultPath As String = vbNullString) As Class1
    Dim Instance As Class1
    Set Instance = New Class1
    Set Create = Instance
End Function

Private Sub Class_Terminate()
    Debug.Print CStr(Timer()) & ": Class1 Class_Terminate"
End Sub

Class2.cls

'@PredeclaredId
Option Explicit

Private Type TClass2
    DllMan As Class1
End Type
Private this As TClass2

'@DefaultMember
Public Function Create(ByVal DllPath As String) As Class2
    Dim Instance As Class2
    Set Instance = New Class2
    Instance.Init DllPath
    Set Create = Instance
End Function

Friend Sub Init(ByVal DllPath As String)
    Dim FileNames As Variant
    Set this.DllMan = Class1.Create(DllPath)
End Sub

Private Sub Class_Terminate()
    Debug.Print CStr(Timer()) & ": Class2 Class_Terminate"
End Sub
rubberduck vba excel
2 Answers

That flickering that you are seeing when Excel is hanging is basically Excel trying to clear an object from memory but failing. I know that for sure because the same thing happens if inside a userform there is a private custom class that doesn't get set to Nothing before the form unloads.

If you add this code to your Class2:

Friend Sub Clear()
    Set this.DllMan = Nothing
End Sub

and then update this:

Assert.IsNotNothing dbm

to this:

Assert.IsNotNothing dbm
dbm.Clear

inside the test method then the issue is gone.

Moreover, if I update the test method:

'@TestMethod("Factory")
Private Sub ztcCreate_VerifiesDefaultManager()
    Dim dbm As Class2
    Set dbm = Class2.Create(ThisWorkbook.Path)
    #If USE_ASSERT_OBJECT Then
        Assert.IsNotNothing dbm
        Debug.Print "Before Clear"
        dbm.Clear
        Debug.Print "After Clear"
    #Else
        Assert.IsTrue Not dbm Is Nothing
    #End If
    Debug.Print "After Test"
End Sub

then after I run the test I get this in the Immediate window:
image1

and only after about 7 seconds I get the last line:
image2

This suggests to me that the Assert.IsNotNothing holds on to the reference for longer than it should.

Edit #1

Removing the Clear method and changing the Terminate event for Class2 to this:

Private Sub Class_Terminate()
    Set this.DllMan = Nothing
    Debug.Print CStr(Timer()) & ": Class2 Class_Terminate"
End Sub

seems to also solve the issue. The only difference is that now both classes get delayed, as expected. So, the delay itself doesn't seem to be an issue.

user_84889130

I have amended the original code and ran a few more experiments exposing some odd behavior as illustrated below. While the nature of the problem is still unclear and appears to be associated with RDVBA (I think I now have sufficient evidence to create an RDVBA issue), I have narrowed down the problem and found a workaround.

In short, I originally had this test Assert.IsNotNothing dbm, and with instrumented code, I observed odd termination timing/sequence. The amended code includes a conditional compilation structure for illustrative purposes. When Assert.IsTrue Not dbm Is Nothing construct is selected instead, both symptoms and the issue are gone.

user_174729880
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