Activity Monitor glossary
What the processes, columns and figures in Activity Monitor mean, when they are a problem, and what to do about it. 34 terms.
Processes you will see
The system processes near the top of the list, what they do, and when they are worth a look.
- kernel_task kernel_task is the macOS kernel as it appears in Activity Monitor.
- WindowServer WindowServer is the macOS system process that manages windows, composites what apps draw into the final image on your displays, and routes input events such as clicks and key presses to the right app.
- mds_stores and mdworker mds, mds_stores and mdworker are the macOS processes that build and maintain the Spotlight search index.
- launchd launchd is the first process macOS starts at boot, with process ID 1.
- Helper processes Helper processes are separate processes an app starts to do part of its work, such as rendering web pages, running extensions, or handling graphics.
- coreaudiod coreaudiod is the macOS background process for Core Audio, the system that handles sound input and output.
- backupd backupd is the Time Machine backup process in macOS.
- photoanalysisd photoanalysisd is the macOS process that analyzes your Photos library in the background.
- syspolicyd syspolicyd is the macOS system policy process.
- cloudd cloudd is the macOS process behind CloudKit, which apps use to store and sync data with iCloud.
Memory
What each figure on the Memory tab means, and which one tells you whether you need more.
- Memory pressure Memory pressure is Activity Monitor's graph of how well the Mac's RAM is meeting current demand.
- App Memory App Memory is the amount of RAM being used by apps and their processes.
- Wired Memory Wired Memory is RAM the system needs to operate that must stay in physical memory.
- Compressed memory Compressed memory is data in RAM that macOS has compressed to make more RAM available.
- Cached Files Cached Files is the size of files macOS has kept in otherwise unused memory to improve performance.
- Swap Used Swap Used is the amount of space on the startup disk that macOS is using to move memory out of RAM and back again.
- Memory column The Memory column in Activity Monitor shows how much memory each process is using.
CPU, GPU and energy
The columns on the CPU, GPU and Energy tabs, and why the numbers look the way they do.
- % CPU % CPU is the share of processor capacity a process is using, measured per CPU core.
- Energy Impact Energy Impact is a relative measure of how much energy an app is using right now, shown in the Energy tab of Activity Monitor.
- Idle Wake Ups Idle Wake Ups counts how many times a process has woken the CPU from an idle state.
- Load average Load average is the average amount of work that is running or waiting to run on the CPU, usually shown as three numbers for the last 1, 5, and 15 minutes.
- Threads A thread is a separate line of execution inside a process, and a process can run several threads at the same time on different CPU cores.
- App Nap App Nap is a macOS feature that slows down apps you are not using, such as apps whose windows are hidden and that are not playing audio.
- Preventing Sleep Preventing Sleep is a column in the Energy tab of Activity Monitor that shows whether an app is currently keeping the Mac from going to sleep.
- % GPU % GPU is the share of the graphics processor's capacity that a process is using.
- Thermal throttling Thermal throttling is when a computer lowers its processor speed to keep temperatures in a safe range.
When something goes wrong
Stuck apps, stuck ports and the tools for finding out why.
- Force Quit Force Quit ends an app or process immediately, without letting it save or clean up.
- Sample Process Sample Process is an Activity Monitor tool that records what a selected process is doing over a few seconds and produces a text report of where its threads spend their time.
- Spindump A spindump is a diagnostic report that records what processes on a Mac were doing, used to investigate apps that hang or stop responding.
- PID A PID, or process ID, is a number macOS assigns to each running process to identify it.
- Listening port A listening port is a network port where a process is waiting for incoming connections, such as a web server on port 3000.
- Spinning wait cursor The spinning wait cursor, often called the spinning beach ball, is the rainbow pointer macOS shows when an app has not responded to input for a few seconds.
- Not Responding Not Responding is the label macOS gives an app that has stopped handling input.
- Zombie process A zombie process is a process that has finished running but still has an entry in the process table, because its parent process has not yet collected its exit status.