MacOS – Monitoring network usage of individual applications

There is a bug in Activity Monitor v10.8.0 (806). If you select Dock Icon > Show CPU History, is automatically closes the floating window and appears in the dock. If you attempt to switch back to the floating window, sometimes only one core appears.

Solution: - Close floating windows - Dock Icon > Show Memory Usage - Quit and Restart Activity Monitor - Dock Icon > Show Application Icon - Quit and Restart Activity Monitor - Monitors > Show CPU History

Now you should see all of your cores/vccores. :-)

This bug is not always reproducible, but I've experienced it before.

To see if CPU or memory is the issue you might start with iostat and vm_stat You would run these from a Terminal.

To get it to continually record you need to run it as

iostat n

where n is the number of seconds between executions.

If you need to look at memory usage then you would want

vm_stat n

If you want to get information on a particular program then you would probably need to write a script that called something like

ps wwaux | grep your_program_name 

over and over.