fix: avoid fetching empty metrics (kubewharf#98)

As metricsFetcher.GetContainerMetric and cpuResourceAdvisor.update are called in separate goroutines,
the latter may be executed before the former, resulting in obtaining empty metrics and
falling back to using pod requests as estimated resources, which leads to a sharp decrease in headroom.

Signed-off-by: linzhecheng <linzhecheng@bytedance.com>

pkg/agent/sysadvisor/plugin/qosaware/resource/cpu/advisor.go

@@ -155,6 +155,12 @@ func (cra *cpuResourceAdvisor) update() {
 	cra.mutex.Lock()
 	defer cra.mutex.Unlock()
 
+	// skip updating during startup
+	if time.Now().Before(cra.startTime.Add(types.StartUpPeriod)) {
+		klog.Infof("[qosaware-cpu] skip updating: starting up")
+		return
+	}
+
 	// sanity check: if reserve pool exists
 	reservePoolInfo, ok := cra.metaCache.GetPoolInfo(state.PoolNameReserve)
 	if !ok || reservePoolInfo == nil {
@@ -192,12 +198,6 @@ func (cra *cpuResourceAdvisor) update() {
 
 	klog.Infof("[qosaware-cpu] region map: %v", general.ToString(cra.regionMap))
 
-	// skip notifying cpu server during startup
-	if time.Now().Before(cra.startTime.Add(types.StartUpPeriod)) {
-		klog.Infof("[qosaware-cpu] skip notifying cpu server: starting up")
-		return
-	}
-
 	// assemble provision result from each region and notify cpu server
 	calculationResult, err := cra.assembleProvision()
 	if err != nil {