if i == 0 {
					ready.Done()
				}
				if ctx.Err() == nil {
					go churn(i + 1)
				}
			}
			go func() {
				churn(0)
			}()
			ready.Wait()

			fn(b)
			b.ReportMetric(float64(atomic.LoadInt64(&count))/float64(b.N), "concurrent_launches/op")
		}
	}

	benchWriteTo := func(b *testing.B) {
		goroutineProf := Lookup("goroutine")
		b.ResetTimer()