The Core Technologies Blog

Professional Software for Windows Services / 24×7 Operation


Q&A: How do I Rename my Application/Service in AlwaysUp?

Q & A - Rename AlwaysUp Application/Service
  I’m a long-time user of AlwaysUp. Can I rename a service?

— Bonnie

Hi Bonnie.

Unfortunately you can’t rename an application in AlwaysUp. This is because the underlying Windows Services API (which AlwaysUp employs to work its magic) simply does not support that operation. You can change many properties of a service — such as the login account, the startup type and the path to the executable — but not its name.

But all is not lost! You can use AlwaysUp’s “Add Copy” feature to implement a poor-man’s rename…

How to use “Add Copy” to rename your application/service

The basic idea is to duplicate your existing application, give it a different name and remove the original.

To do so:

  1. Highlight the entry you wish to rename in AlwaysUp. (We’ll work with Plex Media Server in this guide.)

  2. From the menu, select Application > Add Copy:

    AlwaysUp: Add Copy

    The familiar Add Application window will appear — containing a clone of the entry you highlighted.

  3. In the Name field, remove the default value (“Copy of…”) and enter the name you desire.

    We simply added a “NEW” prefix but your change will be more meaningful:

    AlwaysUp: Change Application Name
  4. Are you running your application in a specific user account? If so, switch to the Logon tab and enter the password for that Windows account:

    AlwaysUp: Set the Login Password

    You must do this because the “Add Copy” feature does not propagate any passwords — an important security precaution.

  5. And if you are using the email notification feature and have configured an email account with a password, you must re-enter that password as well.

    Switch to the Email tab, click the Configure button and type in your password:

    AlwaysUp: Set the Email Password
  6. We’re done making changes so click the Save button to record your new application. Here you can see our old and new entries, side-by-side:

    AlwaysUp: Copy Created
  7. And finally, delete the original application from AlwaysUp. You no longer need it since you have a new version with the correct name.

    Highlight the original, choose Application > Remove and confirm the prompt to complete the process:

    AlwaysUp: Remove the Original Application

That’s it! Apologies for the multiple steps, but that is the best we can do until Microsoft explicitly supports renaming a Windows Service.

As usual, please get in touch if you have any questions about the process.

Posted in AlwaysUp | Tagged , | Leave a comment

Q&A: Why Doesn’t AlwaysUp Catch my Endless Loop?

Q & A - Detect Infinite Loops
  Following your AlwaysUp documentation, I am using the “Monitor the application and stop it whenever it hangs” option. When I set its value to 1 minute, this feature does not work as I expect.

I wrote a simple application that goes into an endless loop after one minute of execution time. But the application is not restarted by AlwaysUp. Why not?

— Beatrix

Hi Beatrix. Not all infinite loops can be detected by AlwaysUp. Let me explain…

AlwaysUp catches non-responsive GUI applications

AlwaysUp’s hang detection feature is designed to identify a specific situation — where a Windows GUI application is not responding to the operating system.

We have all encountered this type of hang before. It happens when Firefox suddenly locks up, or when Excel goes gray and the cursor turns into a spinning wheel. The application is frozen and all input is ignored.

If you are lucky, the disruption only lasts a few seconds; if not, you may have to forcibly terminate the application from the Task Manager. Very annoying!

Beyond the gray window and spinning cursor, there are a couple of telltale signs when an application is hung/non-responsive:

  1. You will see “Not responding” in the application’s title bar.

    Outlook Not Responding
  2. The application’s process will be marked as “Not responding” in the Task Manager:

    Task Manager Process Not Responding

Furthermore, Windows may throw up a warning outlining your very limited options:

Excel Process Not Responding

The good news is that AlwaysUp has you covered in all of those situations!

How AlwaysUp checks if your application is hung

When you enable hang-checking, the AlwaysUp Windows Service component executes the following procedure every few seconds:

  1. Scans the desktop to identify all top-level windows belonging to the application being monitored.

  2. Sends each of those top-level windows a WM_NULL (no-op) message.

  3. Waits a few seconds for each of the windows to acknowledge the message.

  4. Declares the application a hang if no windows respond.

An application that remains hung over the user-supplied duration (1 minute, in your case) will be terminated and restarted.

Not all endless loops result in a frozen/non-responsive application

There are a couple of consequences stemming from the way that AlwaysUp checks for a hang.

First, an application without a top-level window can never be classified as a hang.

For example, this simple, non-GUI C# program that loops forever will escape detection:

using System;
namespace InfiniteLoop {
   class Program {
      static void Main(string[] args) {
         while (true) {
            Thread.Sleep(1000);
         }
      }
   }
}

Second, if an application creates multiple windows, all windows must be non-responsive for AlwaysUp to declare a hang. If even a single window processes the WM_NULL message, the application will be classified as responsive.

My guess is that your endless loop test fits into one of the scenarios above. Unfortunately AlwaysUp’s hang detection feature will not be able to help there. Sorry about that!

But all is not lost…

Use the Sanity Check feature to detect endless loops and other failures

There can be many indications that a program is stuck. For example, an application might:

  • stop responding to requests over the network;

  • stop writing entries to a status file;

  • report an “I have failed” message to a log file;

  • or leave files collecting dust in a specific “inbox” folder

In situations like these — where the failure is detectable by a script or simple utility — you should look to AlwaysUp’s powerful Sanity Check feature. It allows you to extend failure detection to encompass anything you like, including the issues listed above.

The Sanity Check page digs into the technical details, which we will not repeat here. Please review the documentation and get in touch if you need help to use that flexible functionality.

Posted in AlwaysUp | Tagged , , , , | Comments Off on Q&A: Why Doesn’t AlwaysUp Catch my Endless Loop?

Windows Service Patterns

Windows Service Patterns

Windows Services are special applications designed to run unattended on your PC. A service an do virtually anything its programmer demands, such as reading files, sending email, checking for viruses — whatever.

Yet in the midst of that tremendous diversity, the vast majority of services have a lot in common. With inspiration from Professional NT Services, it is our observation that the majority of windows services can be placed in one of four categories: Server, Agent, Processor or Canary.

  1. Server: Accept and fulfill requests for services and/or resources

    The majority of Windows services implement the Server pattern. They typically act as the proxy/gatekeeper to a well-defined area of the operating system, fulfilling requests as they come in.

    For example:

    • Spooler implements the Print Spooler API. It accepts print requests from desktop applications and negotiates with printers to ensure that they all documents are (eventually) printed.

    • User Profile Service is responsible for loading and unloading user information on behalf of all applications.

    • Windows Event Log records application, system and security events through the Event Log API.

  2. Agent: Perform a task regularly on behalf of a person

    Many services implement the Agent pattern. They run in the background, performing requested tasks at pre-defined times.

    For example:

    • Google Update Service keeps your Google software up to date, applying security patches and other improvements as they become available.

    • The Schedule service works in conjunction with the Windows Task Scheduler, launching each scheduled task at its appointed date and time.

    • Windows Update automatically detects, downloads, and installs of updates for Windows and other Microsoft programs.

  3. Processor: Watches for important events then takes action

    A Processor springs to life in response to a triggering event. It has the autonomy to take action and resolve the issue at hand.

    For example:

    • Windows Time ensures that your PC’s clock is correct, synchronizing it with clients and servers in the network.

    • Background Intelligent Transfer Service opportunistically transfers files in the background when network traffic is low.

    • Bluetooth Support Service supports the discovery and pairing of nearby Bluetooth devices.

  4. Canary: Notify a person (or application) when something important happens

    A Canary is a special kind of Processor. It too watches for important events, but its primary task is to shout loudly instead of taking definitive action.

    For example:

    • Windows Defender Advanced Threat Protection Service helps protect against advanced threats by monitoring and reporting security events that happen on the computer.

    • System Event Notification Service monitors system events and notifies subscribers to COM+ Event System of these events.

    • Connected User Experiences and Telemetry enables features that support in-application and connected user experiences. The service manages the event driven collection and transmission of diagnostic and usage information (used to improve the experience and quality of the Windows Platform) when the diagnostics and usage privacy option settings are enabled under Feedback and Diagnostics.

Many desktop applications follow a Windows Service pattern too!

Those four patterns apply to regular desktop applications as well. Most notably:

  • iTunes enables your Apple devices to play any track from your media library. iTunes is a Server.

  • SyncToy will synchronize two file systems on demand. SyncToy is an Agent.

  • Dropbox watches your file system and copies updated files to the server. Dropbox is a Processor.

  • SpeedFan monitors your computer’s voltage, fan speeds and temperatures and lets you know when something is wrong. SpeedFan is a Canary.

If you are responsible for a legacy/desktop application that aligns with one of the four service patterns, you should consider installing it as a Windows Service. It probably should have been built as a service in the first place!

Posted in Windows Services | Tagged , | Leave a comment


Essential Windows Services: Power

Windows Power Service

What is the Power service?

The Power service implements your computer’s power schemes, policies and notifications as configured in the Control Panel:

Control Panel Power Options

The service’s name (and display name) is Power and it runs inside the shared services host process, svchost.exe:

Power Windows Service

Is it safe to disable the Power service?

In their guidance on disabling system services on Windows Server 2016, Microsoft does not indicate that it is OK to disable the Power service. Indeed, they punt on specific guidance altogether, commenting that “the impact of disabling the service has not been fully evaluated”.

Their ultimate recommendation is to stick with the default configuration — automatic start at boot.

The “Stop” button is disabled. How can I stop the Power service?

If you examine the service’s screenshot, you will notice that the Stop button is disabled — indicating that the service cannot be stopped.

And even the versatile NET STOP command run as an administrator will fail, complaining that the service isn’t in the right “state”:

Net stop Power fails

This is different from the typical permission/rights problem seen when attempting to stop other important services. Here, the Power service is actively refusing to be stopped under any condition and there is no way around it.

What will happen if I kill the Power service’s process?

Your computer will shut down, immediately.

This is because the Power service is hosted by an instance of the shared service host process (svchost.exe) also running these core services:

  • Background Tasks Infrastructure Service / BrokerInfrastructure: Responsible for background tasks.

  • DCOM Server Process Launcher / DcomLaunch: Launches COM & DCOM servers.

  • Local Session Manager / LSM: Manages local user sessions.

Task Manager will confirm that all four services have the same PID (process identifier):

The Power Service in Task Manager

So killing that svchost process will stop all four services.

If you choose to press on and try to end the process, Task Manager will warn you of the dire consequences:

Kill Power Service warning

And that is no idle threat! We were greeted with this delightful blue screen of death after terminating the process on our Windows Server 2019 machine:

Blue screen of Death: A critical process died

Be careful!

The Power service isn’t starting. Help!

We suggest the following:

  1. Reboot your computer. Hopefully you have fallen victim to a temporary glitch and sanity will be restored when the operating system next starts.

  2. Manually run Windows Update. If you’re lucky, the Microsoft Windows engineers have already found and fixed the problem with their software.

  3. Seek expert help. Start with a google search for a quick fix; move on to your local administrator if no resolution is forthcoming.

  4. Reinstall Windows. You may have to start over from scratch if nothing else works… 🙁

Questions? Problems?

If you would like to know more about the Windows Power service, or you have a specific problem, please feel free to get in touch. We will do our best to help you!

Posted in Windows Services | Tagged , , | 1 Comment