htop on Mac shows 0% CPU for some processes

Short answer

macOS only lets a process read CPU and memory counters for processes owned by the same user. htop runs as you, so for processes owned by root or system users (WindowServer, mds_stores, kernel_task) it gets nothing and shows 0.0%, 0 memory and 0:00.00 CPU time. Run it with sudo htop, or use top or ps.

See it for yourself

Here is WindowServer in htop 3.4.1, run without sudo:

  606 _windowser  17   0     0     0 ?   0.0  0.0  0:00.00 WindowServer

At the same moment, top reported it at about 63% CPU:

top -l 2 -n 10 -o cpu -stats pid,command,cpu,user

606    WindowServer     63.7 _windowserver

The difference is how they are installed:

ls -l /usr/bin/top /bin/ps

-r-sr-xr-x  1 root  wheel  240624 Aug  1 17:15 /usr/bin/top
-rwsr-xr-x  1 root  wheel  170432 Aug  1 17:15 /bin/ps

The s in the permissions means setuid: Apple's top and ps run as root, so they can read every process. A Homebrew htop is an ordinary binary owned by you.

Your options

• sudo htop shows everything, for as long as that session runs.
• top or ps -axo pid,user,%cpu,comm already see every process.
• Avoid making htop itself setuid root. Anything it can do (including sending signals to any process) would then be available without a password.

The easier way: GaugeMon

GaugeMon is an htop-style process list for the Mac: per-core meters, load average, tree view and signals. It lists every process without sudo, and its optional privileged helper, installed from Settings, fills in CPU and memory for root and system processes so nothing reads 0% by mistake.

Related guides

• WindowServer high CPU on Mac
• kernel_task using high CPU on Mac