I’ve previously covered one issue here about overheating macs, but kernel_task is not the only process that can get out of hand. For example, there’s a known issue with some releases of Parallels that can cause a process called prl_disp_service to run up to 99% too, leaving your mac sweating on the desktop even on a cold Winter’s eve!
In general, ‘hot’ issues can be found by looking at what’s going on in your Activity monitor, and solved by quitting (or force quitting) the process. Also, don’t wait to discover these by how hot your mac feels to the touch. Download and install a free copy of smcFanControl and have it running in the menubar. Now you’ll have a reliable means of seeing exactly how hot your mac is. 🙂
However, some processes may not re-start correctly after being quit in Activity monitor unless you reboot the machine or work a bit of Terminal magic. In the case of Parallels, for example, if you’ve identified prl-disp_service as the culprit, the correct solution is to first stop your VM and quit Parallels. Then, open Terminal.app and follow this procedure:
1. Paste this command into Terminal
sudo launchctl stop com.parallels.desktop.launchdaemon
Press ‘Return’. You will be prompted for your password. Note that when you type it in, your typing will be invisible. Press ‘Return’ again.
2. Now paste this command:
sudo launchctl start com.parallels.desktop.launchdaemon
and press ‘Return’.
3. You need to check that the process has correctly restarted before trying to start up Parallels, so one last command:
sudo launchctl list | grep com.parallels.desktop.launchdaemon
The output should look something like this:
36468 – com.parallels.desktop.launchdaemon
The number on the left will be different, but so long as it is anything except 0, you are good to go!
4. Finally, in Terminal, hold down the ‘control‘ key and press the ‘c‘ key at the same time. Now you can quit Terminal and get back to a cool Mac and your Parallels VM. 🙂
You can use these same ‘stop’, ‘start’, and ‘grep’ commands for other errant processes, but you need to find the correct name of the process. You can do this by first noting its name in Activity monitor, then in Terminal, paste:
sudo launchctl list
Look for a launchdaemon that corresponds with the name you found in Activity monitor. Then use the commands above but replace ‘com.parallels.destkop.launchdaemon’ with the name of the process you want to kill.**
**Warning: The sudo command gives you root privileges to the computer and can cause irreparable harm to your OS if used incorrectly. Never mess around with the sudo command unless you have a recent bootable clone of your system.