How can I prevent launching multiple instances of apps and programs?

Fellwalker · 22 Jul 2020

Is there a way in Windows 10 to prevent apps and programs from opening more than one instance? I am aware of a very few that have an internal setting to prevent this (eg Irfanview), but most do not.
I am finding that I am being asked for help because older friends' computers have slowed, to find that they have 2 or 3 browser windows open (as well as tabs in them), and sometimes a couple of instances of other apps.

This is particularly a problem on older slower PCs - which they are likely to have.
The issue seems to be that if an app does not immediately start up or show an egg timer, the expectation is that the click to open did not register, so a second or third click is made. Then when I log in using TeamViewer, I find all of those instances open, and the computer almost at standstill. In some cases it is the user pressing the windows key and typing the app name - which instead of opening the existing instance, creates a new one.

I've searched, and there are no threads I can find that cover this issue. Some cover problems with corrupted apps when many multiple instances are launched, or by a system error. There is one website that is shown in search results with a summary recommending an app called 'single instance', but I cannot find any reviews of that site, nor of the app, nor other mentions. I am not inclined to risk either visiting that site or that of the app, let alone installing it.

Does anyone please have any solutions to restrict apps to a single instance?

Windows 10 v1909. Build 18363.959.
Most of the people I help out have v 1909, one still has 1903 because their hardware is inadequate.

dalchina · 22 Jul 2020

As you've noted, that's something built into programs- or not.

You could...
- for each program type to be launched, replace the shortcut with a schortcut to a script that checks if there is an existing instance of that program, and if so, exit, else launch the program. Easy with Autohotkey.
- More generically: create a script that detects a new program being launched,
Windows Security Log Event ID 4688 - A new process has been created
then test if an instance of that process already exists, and if so, terminate the new program. That could be set as a scheduled task triggered by an event id, or simply run in a continuous loop.
I see all sorts of potential issues with that though.

There are programs that limit CPU use per process, such as BES and Process Tamer (free).
There's Process Lassoo (not free) that claims to balance resource use, and allows setting CPU affinity. I tried it many years ago and didn't find it useful.

Fellwalker · 22 Jul 2020

Thanks @dalchina.
Unfortunately as you say, that isn't really feasible - especially considering that the computers aren't mine, but belonging to friends and relatives that I help out. As such, they are all over the UK and not accessible except by TeamViewer.

TONPumper · 23 Jul 2020

Process Lasso is what I use. It can be pretty useful for limiting certain processes and services, but lately I've decided that I don't like a program that tugs on my CPU more. I do, however, keep it installed for the performance plan that it offers in the Power Settings.