Fix err race condition and partial failure issues

closes #1439
closes #1440
closes #1441
closes #1442
closes #1443
closes #1444
closes #1445

plugins/inputs/nsq/nsq.go

@@ -32,6 +32,7 @@ import (
 	"time"
 
 	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/internal/errchan"
 	"github.com/influxdata/telegraf/plugins/inputs"
 )
 
@@ -65,19 +66,17 @@ func (n *NSQ) Description() string {
 
 func (n *NSQ) Gather(acc telegraf.Accumulator) error {
 	var wg sync.WaitGroup
-	var outerr error
-
+	errChan := errchan.New(len(n.Endpoints))
 	for _, e := range n.Endpoints {
 		wg.Add(1)
 		go func(e string) {
 			defer wg.Done()
-			outerr = n.gatherEndpoint(e, acc)
+			errChan.C <- n.gatherEndpoint(e, acc)
 		}(e)
 	}
 
 	wg.Wait()
-
-	return outerr
+	return errChan.Error()
 }
 
 var tr = &http.Transport{