Split serial and parallel collectors. Read in parallel first

collectors/collectorManager.go

@@ -40,13 +40,16 @@ var AvailableCollectors = map[string]MetricCollector{
 
 // Metric collector manager data structure
 type collectorManager struct {
-	collectors []MetricCollector          // List of metric collectors to use
+	collectors   []MetricCollector          // List of metric collectors to read in parallel
+	serial       []MetricCollector          // List of metric collectors to read serially
 	output       chan lp.CCMetric           // Output channels
 	done         chan bool                  // channel to finish / stop metric collector manager
 	ticker       mct.MultiChanTicker        // periodically ticking once each interval
 	duration     time.Duration              // duration (for metrics that measure over a given duration)
 	wg           *sync.WaitGroup            // wait group for all goroutines in cc-metric-collector
 	config       map[string]json.RawMessage // json encoded config for collector manager
+	collector_wg sync.WaitGroup             // internally used wait group for the parallel reading of collector
+	parallel_run bool                       // Flag whether the collectors are currently read in parallel
 }
 
 // Metric collector manager access functions
@@ -66,6 +69,7 @@ type CollectorManager interface {
 // Initialization is done for all configured collectors
 func (cm *collectorManager) Init(ticker mct.MultiChanTicker, duration time.Duration, wg *sync.WaitGroup, collectConfigFile string) error {
 	cm.collectors = make([]MetricCollector, 0)
+	cm.serial = make([]MetricCollector, 0)
 	cm.output = nil
 	cm.done = make(chan bool)
 	cm.wg = wg
@@ -100,7 +104,11 @@ func (cm *collectorManager) Init(ticker mct.MultiChanTicker, duration time.Durat
 			continue
 		}
 		cclog.ComponentDebug("CollectorManager", "ADD COLLECTOR", collector.Name())
+		if collector.Parallel() {
 			cm.collectors = append(cm.collectors, collector)
+		} else {
+			cm.serial = append(cm.serial, collector)
+		}
 	}
 	return nil
 }
@@ -116,6 +124,10 @@ func (cm *collectorManager) Start() {
 		// Collector manager is done
 		done := func() {
 			// close all metric collectors
+			if cm.parallel_run {
+				cm.collector_wg.Wait()
+				cm.parallel_run = false
+			}
 			for _, c := range cm.collectors {
 				c.Close()
 			}
@@ -130,7 +142,26 @@ func (cm *collectorManager) Start() {
 				done()
 				return
 			case t := <-tick:
+				cm.parallel_run = true
 				for _, c := range cm.collectors {
+					// Wait for done signal or execute the collector
+					select {
+					case <-cm.done:
+						done()
+						return
+					default:
+						// Read metrics from collector c via goroutine
+						cclog.ComponentDebug("CollectorManager", c.Name(), t)
+						cm.collector_wg.Add(1)
+						go func(myc MetricCollector) {
+							myc.Read(cm.duration, cm.output)
+							cm.collector_wg.Done()
+						}(c)
+					}
+				}
+				cm.collector_wg.Wait()
+				cm.parallel_run = false
+				for _, c := range cm.serial {
 					// Wait for done signal or execute the collector
 					select {
 					case <-cm.done: