Every so often you Mac will use 100% of it system resources trying to complete a task. This is not normally a problem, however you may want to pause an application or a process so you can quickly complete another task. For example if iTunes is using 100% of our system, you may want to temporarily pause it to free up you system. You can then re-enable it and allow the application to resume. I like to use this trick if I want to quickly run a CPU intensive app while my system is running and I want to give it all of my system resources, but something is taking up the CPU cycles.
Pausing An Application
To pause an application we first need to find it’s PID. This is a unique number that identifies the application or process that is running. To find this ID open Activity Monitor located in your Applications > Utilities folder.
One of the columns should be named PID, if you can’t find this column, go to View > Columns and select the Process ID option. Find the process you want to pause and take a note of its number. You can sort the columns so it isn’t too hard to find the one that is taking up 100% of you system.
Now we have the number open Terminal located in your Applications > Utilities folder. Type the following into the Terminal window.
kill -STOP 1234
You will notice that the application will be paused and it will not be accepting inputs or outputs. This can be tested on pretty much any application, for example if you try it with iTunes, it will stop playing music, quick time will stop playing videos any app which have this command applied will be paused.
To start an application again type the following into Terminal. Note that the same PID number should be used.
kill -CONT 1234
It is a simple trick but one that is very useful. For example if iTunes is taking for ever to import a music video, or quicktime is taking its time to export a video, you can use this trick to pause the application, do something else and then restart the app.
I don’t recommend you use this trick every single day,simply because if the application is expecting an input and it paused it may cause the application to crash. However, if it is to pause an application only briefly while something else jumps in to use your system you may be able to get away with it.
There was an application out there that allowed you to do this from the Task bar, however this has since been discontinued.