Average memory metrics instead of summing (#362)

* Average RSS and VMS memory metrics and update unit tests for average mem metrics

---------

Co-authored-by: Oliver O'Mahony <[email protected]>

src/core/metrics/metrics_util.go

@@ -242,8 +242,8 @@ func GetCalculationMap() map[string]string {
 		"nginx.workers.cpu.system":                           "sum",
 		"nginx.workers.cpu.total":                            "sum",
 		"nginx.workers.fds_count":                            "avg",
-		"nginx.workers.mem.vms":                              "sum",
-		"nginx.workers.mem.rss":                              "sum",
+		"nginx.workers.mem.vms":                              "avg",
+		"nginx.workers.mem.rss":                              "avg",
 		"nginx.workers.mem.rss_pct":                          "avg",
 		"nginx.workers.io.kbs_r":                             "sum",
 		"nginx.workers.io.kbs_w":                             "sum",

src/core/metrics/sources/nginx_worker.go

@@ -86,16 +86,6 @@ func (c *NginxWorker) Collect(ctx context.Context, wg *sync.WaitGroup, m chan<-
 			cpuSystem = stats.Workers.CPUSystem
 		}
 
-		memRss := stats.Workers.MemRss - c.prevStats[pid].Workers.MemRss
-		if stats.Workers.MemRss < c.prevStats[pid].Workers.MemRss {
-			memRss = stats.Workers.MemRss
-		}
-
-		memVms := stats.Workers.MemVms - c.prevStats[pid].Workers.MemVms
-		if stats.Workers.MemVms < c.prevStats[pid].Workers.MemVms {
-			memVms = stats.Workers.MemVms
-		}
-
 		KbsR := stats.Workers.KbsR - c.prevStats[pid].Workers.KbsR
 		if stats.Workers.KbsR < c.prevStats[pid].Workers.KbsR {
 			KbsR = stats.Workers.KbsR
@@ -113,8 +103,8 @@ func (c *NginxWorker) Collect(ctx context.Context, wg *sync.WaitGroup, m chan<-
 			"cpu.system":    float64(cpuSystem),
 			"cpu.total":     float64(cpuSystem + cpuUser),
 			"fds_count":     float64(stats.Workers.FdsCount),
-			"mem.vms":       float64(memVms),
-			"mem.rss":       float64(memRss),
+			"mem.vms":       float64(stats.Workers.MemVms),
+			"mem.rss":       float64(stats.Workers.MemRss),
 			"mem.rss_pct":   float64(stats.Workers.MemRssPct),
 			"io.kbs_r":      float64(KbsR),
 			"io.kbs_w":      float64(KbsW),

src/core/metrics/sources/nginx_worker_test.go

@@ -108,15 +108,15 @@ func TestNginxWorkerCollector(t *testing.T) {
 		case "nginx.workers.io.kbs_r":
 			assert.Equal(t, float64(0), metric.Value)
 		case "nginx.workers.mem.rss":
-			assert.Equal(t, float64(0), metric.Value)
+			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.mem.rss_pct":
 			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.rlimit_nofile":
 			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.count":
 			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.mem.vms":
-			assert.Equal(t, float64(0), metric.Value)
+			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.fds_count":
 			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.cpu.user":
@@ -148,15 +148,15 @@ func TestNginxWorkerCollector(t *testing.T) {
 		case "nginx.workers.io.kbs_r":
 			assert.Equal(t, float64(0), metric.Value)
 		case "nginx.workers.mem.rss":
-			assert.Equal(t, float64(0), metric.Value)
+			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.mem.rss_pct":
 			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.rlimit_nofile":
 			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.count":
 			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.mem.vms":
-			assert.Equal(t, float64(0), metric.Value)
+			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.fds_count":
 			assert.Equal(t, float64(1), metric.Value)
 		case "nginx.workers.cpu.user":