GODEBUG=gctrace=1 in the environment to get log output from a Go program whenever the garbage collector runs.
gc 1 @10.282s 0%: 0.12+0.17+0.10 ms clock, 0.38+0/0.053/0.19+0.30 ms cpu, 4->4->0 MB, 5 MB goal, 4 P
The clock and cpu sections give us details on how long the GC cycle took. In this case we can see that it took well under 1ms.
See https://golang.org/pkg/runtime/ for details on what the output means.Tweet