What is spindump on a Mac, and why does it run when an app hangs?
spindump records what a frozen app was doing, for the hang report. It ran on our Mac for a few minutes after an app stopped responding. Where its reports go.
What is spindump?
When an app stops responding, or you ask for a diagnostic report, macOS runs spindump to sample every thread of the stuck process and record where it was waiting. It runs as root and quits when the report is written. On our Mac it had been running for six minutes at 1 MB, next to two ReportCrash processes.
Where do the reports go?
ls -lt /Library/Logs/DiagnosticReports ~/Library/Logs/DiagnosticReports | headHang reports end in .hang or .spin, crash reports in .ips. They are small and rotate, but a Mac with an app hanging often collects many. Larger diagnostic bundles are covered in sysdiagnose files.
Can I stop spindump?
It stops by itself once the report is done. The useful move is reading the newest report's first lines: the process name tells you which app hung, which is the problem to fix.
See it live
Free Mac's System tab ranks every process by processor use and energy impact, once a second, and marks the ones macOS will not let you quit as protected. See also logd and app logs.
Related: ControlCenter high CPU and Dock using high CPU.
Common questions
What is spindump on a Mac?
A macOS tool that samples a frozen app's threads to write a hang report. It quits when done.
Why is spindump using CPU?
An app has hung and spindump is recording what it was doing.
Where are spindump reports saved?
In /Library/Logs/DiagnosticReports and ~/Library/Logs/DiagnosticReports, as .hang or .spin files.