From 02735ee64db14784f7ca1a740461e65db502559b Mon Sep 17 00:00:00 2001
From: Chris Hines <github@cs-guy.com>
Date: Sun, 22 May 2016 22:02:25 -0400
Subject: [PATCH] Improve log.testConcurrency to check errors and control total
 event count.

---
 log/concurrency_test.go   | 36 ++++++++++++++++++++++++------------
 log/json_logger_test.go   |  3 ++-
 log/logfmt_logger_test.go |  3 ++-
 log/sync_test.go          |  7 ++++---
 4 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/log/concurrency_test.go b/log/concurrency_test.go
index e68d16a3e..95a749e77 100644
--- a/log/concurrency_test.go
+++ b/log/concurrency_test.go
@@ -1,8 +1,7 @@
 package log_test
 
 import (
-	"strconv"
-	"sync"
+	"math"
 	"testing"
 
 	"github.com/go-kit/kit/log"
@@ -10,19 +9,32 @@ import (
 
 // These test are designed to be run with the race detector.
 
-func testConcurrency(t *testing.T, logger log.Logger) {
-	for _, n := range []int{10, 100, 500} {
-		wg := sync.WaitGroup{}
-		wg.Add(n)
-		for i := 0; i < n; i++ {
-			go func() { spam(logger); wg.Done() }()
+func testConcurrency(t *testing.T, logger log.Logger, total int) {
+	n := int(math.Sqrt(float64(total)))
+	share := total / n
+
+	errC := make(chan error, n)
+
+	for i := 0; i < n; i++ {
+		go func() {
+			errC <- spam(logger, share)
+		}()
+	}
+
+	for i := 0; i < n; i++ {
+		err := <-errC
+		if err != nil {
+			t.Fatalf("concurrent logging error: %v", err)
 		}
-		wg.Wait()
 	}
 }
 
-func spam(logger log.Logger) {
-	for i := 0; i < 100; i++ {
-		logger.Log("key", strconv.FormatInt(int64(i), 10))
+func spam(logger log.Logger, count int) error {
+	for i := 0; i < count; i++ {
+		err := logger.Log("key", i)
+		if err != nil {
+			return err
+		}
 	}
+	return nil
 }
diff --git a/log/json_logger_test.go b/log/json_logger_test.go
index 78697b6cf..42df70c1c 100644
--- a/log/json_logger_test.go
+++ b/log/json_logger_test.go
@@ -153,5 +153,6 @@ func BenchmarkJSONLoggerContextual(b *testing.B) {
 }
 
 func TestJSONLoggerConcurrency(t *testing.T) {
-	testConcurrency(t, log.NewJSONLogger(ioutil.Discard))
+	t.Parallel()
+	testConcurrency(t, log.NewJSONLogger(ioutil.Discard), 10000)
 }
diff --git a/log/logfmt_logger_test.go b/log/logfmt_logger_test.go
index 9e7361ff3..91bbca15c 100644
--- a/log/logfmt_logger_test.go
+++ b/log/logfmt_logger_test.go
@@ -48,7 +48,8 @@ func BenchmarkLogfmtLoggerContextual(b *testing.B) {
 }
 
 func TestLogfmtLoggerConcurrency(t *testing.T) {
-	testConcurrency(t, log.NewLogfmtLogger(ioutil.Discard))
+	t.Parallel()
+	testConcurrency(t, log.NewLogfmtLogger(ioutil.Discard), 10000)
 }
 
 type mymap map[int]int
diff --git a/log/sync_test.go b/log/sync_test.go
index 07960c9b6..3d915ec7b 100644
--- a/log/sync_test.go
+++ b/log/sync_test.go
@@ -52,7 +52,8 @@ func TestSwapLogger(t *testing.T) {
 }
 
 func TestSwapLoggerConcurrency(t *testing.T) {
-	testConcurrency(t, &log.SwapLogger{})
+	t.Parallel()
+	testConcurrency(t, &log.SwapLogger{}, 10000)
 }
 
 func TestSyncLoggerConcurrency(t *testing.T) {
@@ -60,12 +61,12 @@ func TestSyncLoggerConcurrency(t *testing.T) {
 	w = &bytes.Buffer{}
 	logger := log.NewLogfmtLogger(w)
 	logger = log.NewSyncLogger(logger)
-	testConcurrency(t, logger)
+	testConcurrency(t, logger, 10000)
 }
 
 func TestSyncWriterConcurrency(t *testing.T) {
 	var w io.Writer
 	w = &bytes.Buffer{}
 	w = log.NewSyncWriter(w)
-	testConcurrency(t, log.NewLogfmtLogger(w))
+	testConcurrency(t, log.NewLogfmtLogger(w), 10000)
 }