Execution Tracing and the Flight Recorder

An airliner carries a flight data recorder, a box that records the aircraft's instruments throughout every flight. It does not keep everything from the first flight onward. It records over its oldest data and always holds the most recent stretch, so that after an incident, investigators can read what happened in the minutes before it.

A Go program can run the same kind of recorder for its own execution. The runtime can record, with nanosecond timestamps, when each goroutine started, when it blocked and on what, when it was woken, and which P ran it. That record is called an execution trace