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dotnet component services : The object that wouldn't die
I have a COM+ application with one object that is never destroyed. Each time
I run the client application that uses it, the a new instance of the object is created. Even though the object is set to null by the client, it never gets garbage collected. The only way to destroy the object instances that have accumulated during sucessive runs is to shut down the application in the Component Services snap-in. But, this only happens when running on Win2003. Running the application on a 2000 or XP box, it works fine. I have found one other reference to this in an archive of this newsgroup (see http://www.dotnet247.com/247reference//msgs/53/267739.aspx). Does anyone know what causes this, and is a solution to it known? Paul Taylor
Below is code to demonstrate the problem.=20
Create a VS solution with three projects: a.. a Class Library called NeverDies to contain Immortal.vb,=20 b.. a Console app called Client to contain Module1.vb=20 c.. a setup program to deploy the app to a Windows 2003 server. Note that the Finalize method in the Immortal class contains code to = show whether the object gets garbage collected (it doesn't). a.. Deploy the application to a W2K3 server=20 b.. Open the Component Services snap-in c.. Open a trace viewer application (download a freeware version of = DebugView if required from http://www.sysinternals.com/) d.. run Client.exe (this may cause an error on the first run) e.. refresh the COM+ Applications node and open the properties dialog = for the NeverDies application f.. if you got an error when running client.exe, set the application's = Identity to the LocalService account,=20 g.. on the Advanced tab, select "Leave running when idle" h.. OK the changes, select the components node underneath the = NeverDies application and switch the snap-in to Status view i.. if you got an error first time round, run client.exe again j.. observe that the Immortal object has not been destroyed k.. observe that the Finalize method produced no output in the Trace = Viewer, demonstrating that the object was not garbage collected ********************* Immortal.vb ********************* Imports System.Threading Imports System.EnterpriseServices <EventTrackingEnabled()> _ Public Class Immortal Inherits ServicedComponent Private _start As DateTime Public Sub New() _start =3D Now End Sub Public Function Live() As Long Dim rnd As New Random Thread.CurrentThread.Sleep(rnd.Next(1, 3000)) Return Now.Subtract(_start).TotalMilliseconds End Function Protected Overrides Sub Finalize() Trace.WriteLine("Finalized") MyBase.Finalize() End Sub End Class ********************* Add the following attributes to AssemblyInfo.vb in NeverDies project ********************* <Assembly: ApplicationName("NeverDies")>=20 <Assembly: ApplicationID("{49CC81DB-C910-40ec-B5DA-DADF6DFDE917}")>=20 <Assembly: ApplicationActivation(ActivationOption.Server)>=20 <Assembly: ApplicationAccessControl(False)>=20 ********************* Module1.vb ********************* Imports NeverDies Imports System.EnterpriseServices Module Module1 Sub Main() Dim imm As New NeverDies.Immortal Dim iLifeSpan As Integer =3D imm.Live() imm =3D Nothing 'Force garbage collection System.GC.Collect() Console.WriteLine(String.Format("The object lived for {0} = milliseconds", iLifeSpan)) Console.WriteLine("Press a key to continue...") Console.Read() End Sub
You need to dispose the server object, setting it to null will not =
release it. Regards Simon. [quoted text, click to view] "Paul Taylor" <paul.2.taylor@atosorigin.com> wrote in message = Below is code to demonstrate the problem.=20news:OlVQW8ujGHA.3588@TK2MSFTNGP02.phx.gbl... Create a VS solution with three projects: a.. a Class Library called NeverDies to contain Immortal.vb,=20 b.. a Console app called Client to contain Module1.vb=20 c.. a setup program to deploy the app to a Windows 2003 server. Note that the Finalize method in the Immortal class contains code to = show whether the object gets garbage collected (it doesn't). a.. Deploy the application to a W2K3 server=20 b.. Open the Component Services snap-in=20 c.. Open a trace viewer application (download a freeware version of = DebugView if required from http://www.sysinternals.com/)=20 d.. run Client.exe (this may cause an error on the first run)=20 e.. refresh the COM+ Applications node and open the properties = dialog for the NeverDies application=20 f.. if you got an error when running client.exe, set the = application's Identity to the LocalService account,=20 g.. on the Advanced tab, select "Leave running when idle"=20 h.. OK the changes, select the components node underneath the = NeverDies application and switch the snap-in to Status view=20 i.. if you got an error first time round, run client.exe again=20 j.. observe that the Immortal object has not been destroyed=20 k.. observe that the Finalize method produced no output in the Trace = Viewer, demonstrating that the object was not garbage collected ********************* Immortal.vb ********************* Imports System.Threading Imports System.EnterpriseServices <EventTrackingEnabled()> _ Public Class Immortal Inherits ServicedComponent Private _start As DateTime Public Sub New() _start =3D Now End Sub Public Function Live() As Long Dim rnd As New Random Thread.CurrentThread.Sleep(rnd.Next(1, 3000)) Return Now.Subtract(_start).TotalMilliseconds End Function Protected Overrides Sub Finalize() Trace.WriteLine("Finalized") MyBase.Finalize() End Sub End Class ********************* Add the following attributes to AssemblyInfo.vb in NeverDies project ********************* <Assembly: ApplicationName("NeverDies")>=20 <Assembly: ApplicationID("{49CC81DB-C910-40ec-B5DA-DADF6DFDE917}")>=20 <Assembly: ApplicationActivation(ActivationOption.Server)>=20 <Assembly: ApplicationAccessControl(False)>=20 ********************* Module1.vb ********************* Imports NeverDies Imports System.EnterpriseServices Module Module1 Sub Main() Dim imm As New NeverDies.Immortal Dim iLifeSpan As Integer =3D imm.Live() imm =3D Nothing 'Force garbage collection System.GC.Collect() Console.WriteLine(String.Format("The object lived for {0} = milliseconds", iLifeSpan)) Console.WriteLine("Press a key to continue...") Console.Read() End Sub
Thanks Simon, that does the trick. I was surprised - I didn't =
implemented a Dispose method on the object as it doesn't use any = unmanaged resources. It must be the base class (ServicedComponent) that = requires to be Disposed before it can be released. I guess it must = create an external reference to itself in COM+ that prevents it from = being garbage collected. Some clear documentation from Microsoft about = this would be welcome. Paul [quoted text, click to view] "Simon Hart" <srhartone@yahoo.com> wrote in message = You need to dispose the server object, setting it to null will not =news:ew3glZxkGHA.4596@TK2MSFTNGP02.phx.gbl... release it. Regards Simon. [quoted text, click to view] "Paul Taylor" <paul.2.taylor@atosorigin.com> wrote in message = Below is code to demonstrate the problem.=20news:OlVQW8ujGHA.3588@TK2MSFTNGP02.phx.gbl... Create a VS solution with three projects: a.. a Class Library called NeverDies to contain Immortal.vb,=20 b.. a Console app called Client to contain Module1.vb=20 c.. a setup program to deploy the app to a Windows 2003 server. Note that the Finalize method in the Immortal class contains code to = show whether the object gets garbage collected (it doesn't). a.. Deploy the application to a W2K3 server=20 b.. Open the Component Services snap-in=20 c.. Open a trace viewer application (download a freeware version = of DebugView if required from http://www.sysinternals.com/)=20 d.. run Client.exe (this may cause an error on the first run)=20 e.. refresh the COM+ Applications node and open the properties = dialog for the NeverDies application=20 f.. if you got an error when running client.exe, set the = application's Identity to the LocalService account,=20 g.. on the Advanced tab, select "Leave running when idle"=20 h.. OK the changes, select the components node underneath the = NeverDies application and switch the snap-in to Status view=20 i.. if you got an error first time round, run client.exe again=20 j.. observe that the Immortal object has not been destroyed=20 k.. observe that the Finalize method produced no output in the = Trace Viewer, demonstrating that the object was not garbage collected ********************* Immortal.vb ********************* Imports System.Threading Imports System.EnterpriseServices <EventTrackingEnabled()> _ Public Class Immortal Inherits ServicedComponent Private _start As DateTime Public Sub New() _start =3D Now End Sub Public Function Live() As Long Dim rnd As New Random Thread.CurrentThread.Sleep(rnd.Next(1, 3000)) Return Now.Subtract(_start).TotalMilliseconds End Function Protected Overrides Sub Finalize() Trace.WriteLine("Finalized") MyBase.Finalize() End Sub End Class ********************* Add the following attributes to AssemblyInfo.vb in NeverDies project ********************* <Assembly: ApplicationName("NeverDies")>=20 <Assembly: ApplicationID("{49CC81DB-C910-40ec-B5DA-DADF6DFDE917}")>=20 <Assembly: ApplicationActivation(ActivationOption.Server)>=20 <Assembly: ApplicationAccessControl(False)>=20 ********************* Module1.vb ********************* Imports NeverDies Imports System.EnterpriseServices Module Module1 Sub Main() Dim imm As New NeverDies.Immortal Dim iLifeSpan As Integer =3D imm.Live() imm =3D Nothing 'Force garbage collection System.GC.Collect() Console.WriteLine(String.Format("The object lived for {0} = milliseconds", iLifeSpan)) Console.WriteLine("Press a key to continue...") Console.Read() End Sub
I am not sure you guys are still out there, but where did you add the
dispose? I've a similar problem with a VB6.0 dll in COM+ pack A calling a ..NET Serviced Component in COM+ pack B. THe counters in B just keep increasing, and never go down. In my scenario I am unsure where I would put a dispose? Did you mean my serviced component needs to implement a dispose or the VB app somehow(???) should call dispose. Stan [quoted text, click to view] "Paul Taylor" wrote:
> Thanks Simon, that does the trick. I was surprised - I didn't implemented a Dispose method on the object as it doesn't use any unmanaged resources. It must be the base class (ServicedComponent) that requires to be Disposed before it can be released. I guess it must create an external reference to itself in COM+ that prevents it from being garbage collected. Some clear documentation from Microsoft about this would be welcome. > > Paul > "Simon Hart" <srhartone@yahoo.com> wrote in message news:ew3glZxkGHA.4596@TK2MSFTNGP02.phx.gbl... > You need to dispose the server object, setting it to null will not release it. > > Regards > Simon. > "Paul Taylor" <paul.2.taylor@atosorigin.com> wrote in message news:OlVQW8ujGHA.3588@TK2MSFTNGP02.phx.gbl... > Below is code to demonstrate the problem. > > Create a VS solution with three projects: > a.. a Class Library called NeverDies to contain Immortal.vb, > b.. a Console app called Client to contain Module1.vb > c.. a setup program to deploy the app to a Windows 2003 server. > Note that the Finalize method in the Immortal class contains code to show whether the object gets garbage collected (it doesn't). > a.. Deploy the application to a W2K3 server > b.. Open the Component Services snap-in > c.. Open a trace viewer application (download a freeware version of DebugView if required from http://www.sysinternals.com/) > d.. run Client.exe (this may cause an error on the first run) > e.. refresh the COM+ Applications node and open the properties dialog for the NeverDies application > f.. if you got an error when running client.exe, set the application's Identity to the LocalService account, > g.. on the Advanced tab, select "Leave running when idle" > h.. OK the changes, select the components node underneath the NeverDies application and switch the snap-in to Status view > i.. if you got an error first time round, run client.exe again > j.. observe that the Immortal object has not been destroyed > k.. observe that the Finalize method produced no output in the Trace Viewer, demonstrating that the object was not garbage collected > > ********************* > Immortal.vb > ********************* > Imports System.Threading > Imports System.EnterpriseServices > > <EventTrackingEnabled()> _ > Public Class Immortal > Inherits ServicedComponent > > Private _start As DateTime > > Public Sub New() > _start = Now > End Sub > > Public Function Live() As Long > Dim rnd As New Random > Thread.CurrentThread.Sleep(rnd.Next(1, 3000)) > Return Now.Subtract(_start).TotalMilliseconds > End Function > > Protected Overrides Sub Finalize() > Trace.WriteLine("Finalized") > MyBase.Finalize() > End Sub > > End Class > > ********************* > Add the following attributes to AssemblyInfo.vb in NeverDies project > ********************* > <Assembly: ApplicationName("NeverDies")> > <Assembly: ApplicationID("{49CC81DB-C910-40ec-B5DA-DADF6DFDE917}")> > <Assembly: ApplicationActivation(ActivationOption.Server)> > <Assembly: ApplicationAccessControl(False)> > > > ********************* > Module1.vb > ********************* > Imports NeverDies > Imports System.EnterpriseServices > > > Module Module1 > Sub Main() > Dim imm As New NeverDies.Immortal > Dim iLifeSpan As Integer = imm.Live() > imm = Nothing > 'Force garbage collection > System.GC.Collect() > Console.WriteLine(String.Format("The object lived for {0} milliseconds", iLifeSpan)) > Console.WriteLine("Press a key to continue...") > Console.Read() > End Sub
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