Restart Service when Exception is thrown

Question

I am writing a windows service that needs to be running 24/7. It is a pretty simple service that monitors a directory where files are dropped into and processes those files. I need to restart the service if an unhandled exception is thrown.

Is there a way for a service to restart itself in the event of an unhandled exception?

Answer 1

Have you tried using the Recovery tab of the Service entry - you can set rules for failures, including "Restart the Service" - by default this is on "No Action"

Answer 2

Wrap your service code in a runner which can catch any errors and restart your service.

Answer 3

The best way is to wrap Try / Catch blocks around the methods in the service you can afford to let throw exceptions.

However, there may be serious exceptions thrown that should result in the service being stopped immediately. Don't ignore these! In these cases, handle the exception, log it, email it and then rethrow it. That way you will be informed that the exception has occurred and will know what went wrong. You can then fix the problem and re-start the service manually.

Just ignoring it could cause a major failure in your system which you would not know about. It could also be very expensive on CPU/RAM if the service stops then restarts then stops ad infinitum.

Answer 4

This is able to be done programatically if you wanted, this code was not written by me. I am posting the link to the Authors CodeProject page that contains the source / binaries. Below the link I have explained how I implemented the authors code.

http://www.codeproject.com/KB/install/sercviceinstallerext.aspx

1. Add a reference to the DLL.

2. Open ProjectInstaller.Designer.vb in notepad
   In the InitializeComponent Sub
   CHANGE
   Me.ServiceProcessInstaller1 = New System.ServiceProcess.ServiceProcessInstaller
Me.ServiceInstaller1 = New System.ServiceProcess.ServiceInstaller
   TO
   Me.ServiceProcessInstaller1 = New System.ServiceProcess.ServiceProcessInstaller
Me.ServiceInstaller1 = New Verifide.ServiceUtils.ServiceInstallerEx

3. With the Friend Declarations in the ProjectInstaller.Designer.vb
   CHANGE
   Friend WithEvents ServiceProcessInstaller1 As System.ServiceProcess.ServiceProcessInstaller
Friend WithEvents ServiceInstaller1 As System.ServiceProcess.ServiceInstaller
   TO
   Friend WithEvents ServiceProcessInstaller1 As System.ServiceProcess.ServiceProcessInstaller
Friend WithEvents ServiceInstaller1 As Verifide.ServiceUtils.ServiceInstallerEx

4. CHANGE
   Me.Installers.AddRange(New System.Configuration.Install.Installer() {Me.ServiceProcessInstaller1, Me.ServiceInstaller1})
   TO
   Me.Installers.AddRange(New System.Configuration.Install.Installer() {Me.ServiceInstaller1, Me.ServiceProcessInstaller1})

5. Import The Namespace On ProjectInstaller.vb

6. In ProjectInstaller.vb in the Public Sub New Function After Initialize component function has been called
   ADD
   'Set Reset Time Count - This Is 4 Days Before Count Is Reset
ServiceInstaller1.FailCountResetTime = 60 * 60 * 24 * 4
'ServiceInstaller1.FailRebootMsg = "Houston! We have a problem"

   'Add Failure Actions
ServiceInstaller1.FailureActions.Add(New FailureAction(RecoverAction.Restart, 60000))
ServiceInstaller1.FailureActions.Add(New FailureAction(RecoverAction.Restart, 60000))
ServiceInstaller1.FailureActions.Add(New FailureAction(RecoverAction.None, 3000))

   ServiceInstaller1.StartOnInstall = True

7. Build installer and install. Voila

Answer 5

Hi Aaron.

As suggested by "John Saunders" and "theGecko", you can monitor the service and restart it when it fails. The builtin Windows Service Recovery functionality will get you a long way, but if you find that you need some more advanced features (for example, CPU hogging and hang detection) then please check out Service Protector. It is designed to keep your important Windows Services operating 24x7.

Good luck!