addBuiltin(sSTWStopTrace, "stop trace")
	addBuiltin(sSTWCountPagesInUse, "CountPagesInUse (test)")
	addBuiltin(sSTWReadMetricsSlow, "ReadMetricsSlow (test)")
	addBuiltin(sSTWReadMemStatsSlow, "ReadMemStatsSlow (test)")
	addBuiltin(sSTWPageCachePagesLeaked, "PageCachePagesLeaked (test)")
	addBuiltin(sSTWResetDebugLog, "ResetDebugLog (test)")

	if addErr != nil {
		// This should be impossible but let's be safe.

	}
}

func init() {
	// Enable ReadMemStats' double-check mode.
	*runtime.DoubleCheckReadMemStats = true
}

func TestReadMemStats(t *testing.T) {
	base, slow := runtime.ReadMemStatsSlow()
	if base != slow {
		logDiff(t, "MemStats", reflect.ValueOf(base), reflect.ValueOf(slow))
		t.Fatal("memstats mismatch")
	}
}

func logDiff(t *testing.T, prefix string, got, want reflect.Value) {

		getg().racectx = 0
	})
	metricsUnlock()

	startTheWorld(stw)
}

var DoubleCheckReadMemStats = &doubleCheckReadMemStats

// ReadMemStatsSlow returns both the runtime-computed MemStats and
// MemStats accumulated by scanning the heap.
func ReadMemStatsSlow() (base, slow MemStats) {
	stw := stopTheWorld(stwForTestReadMemStatsSlow)

	// Run on the system stack to avoid stack growth allocation.

	stwForTestCountPagesInUse                       // "CountPagesInUse (test)"
	stwForTestReadMetricsSlow                       // "ReadMetricsSlow (test)"
	stwForTestReadMemStatsSlow                      // "ReadMemStatsSlow (test)"
	stwForTestPageCachePagesLeaked                  // "PageCachePagesLeaked (test)"
	stwForTestResetDebugLog                         // "ResetDebugLog (test)"
)

func (r stwReason) String() string {