From d55fa88dd0d6eb77a2cd263c31206f975c9cb6c4 Mon Sep 17 00:00:00 2001
From: Konstantin Kulikov <k.kulikov2@gmail.com>
Date: Fri, 17 Jun 2016 23:14:29 +0300
Subject: [PATCH] fix datarace in input apache plugin

---
 plugins/inputs/apache/apache.go      | 14 ++++++++------
 plugins/inputs/apache/apache_test.go |  3 ++-
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/plugins/inputs/apache/apache.go b/plugins/inputs/apache/apache.go
index dc5dddb9d..be891bb31 100644
--- a/plugins/inputs/apache/apache.go
+++ b/plugins/inputs/apache/apache.go
@@ -8,7 +8,6 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/influxdata/telegraf"
@@ -38,8 +37,8 @@ func (n *Apache) Gather(acc telegraf.Accumulator) error {
 		n.Urls = []string{"http://localhost/server-status?auto"}
 	}
 
-	var wg sync.WaitGroup
 	var outerr error
+	var errch = make(chan error)
 
 	for _, u := range n.Urls {
 		addr, err := url.Parse(u)
@@ -47,14 +46,17 @@ func (n *Apache) Gather(acc telegraf.Accumulator) error {
 			return fmt.Errorf("Unable to parse address '%s': %s", u, err)
 		}
 
-		wg.Add(1)
 		go func(addr *url.URL) {
-			defer wg.Done()
-			outerr = n.gatherUrl(addr, acc)
+			errch <- n.gatherUrl(addr, acc)
 		}(addr)
 	}
 
-	wg.Wait()
+	// Drain channel, waiting for all requests to finish and save last error.
+	for range n.Urls {
+		if err := <-errch; err != nil {
+			outerr = err
+		}
+	}
 
 	return outerr
 }
diff --git a/plugins/inputs/apache/apache_test.go b/plugins/inputs/apache/apache_test.go
index 8eed61ca6..2a80b3868 100644
--- a/plugins/inputs/apache/apache_test.go
+++ b/plugins/inputs/apache/apache_test.go
@@ -36,7 +36,8 @@ func TestHTTPApache(t *testing.T) {
 	defer ts.Close()
 
 	a := Apache{
-		Urls: []string{ts.URL},
+		// Fetch it 2 times to catch possible data races.
+		Urls: []string{ts.URL, ts.URL},
 	}
 
 	var acc testutil.Accumulator