Added support for memory ballast (#327)

* Added support for memory ballast

---------

Co-authored-by: sbylica-splunk <[email protected]>

README.md

@@ -113,6 +113,7 @@ This is recommended for dev environments only.
 * `SELECTED_MONITORING_METRICS`: Name of the metrics that you want to monitor and add using comma seprated values. List of the metrics that are supported in the metrics modules are given below
 * `REFRESH_SPLUNK_CONNECTION`: If set to true, PCF will periodically refresh connection to Splunk (how often depends on KEEP_ALIVE_TIMER value). If set to false connection will be kept alive and reused. (Default: false)
 * `KEEP_ALIVE_TIMER`: Time after which connection to Splunk will be refreshed, if REFRESH_SPLUNK_CONNECTION is set to true (in s/m/h. For example, 3600s or 60m or 1h). (Default: 30s)
+* `MEMORY_BALLAST_SIZE`: Size of memory allocated to reduce GC cycles. Default is 0, Size should be less than the total memory.
 
 __About app cache params:__
 

main.go

@@ -27,6 +27,11 @@ func main() {
 	signal.Notify(shutdownChan, syscall.SIGINT, syscall.SIGTERM)
 
 	config := splunknozzle.NewConfigFromCmdFlags(version, branch, commit, buildos)
+	if config.MemoryBallastSize > 0 {
+		ballast := make([]byte, config.MemoryBallastSize<<20)
+		_ = ballast
+	}
+
 	if config.AppCacheTTL == 0 && config.OrgSpaceCacheTTL > 0 {
 		logger.Info("Apps are not being cached. When apps are not cached, the org and space caching TTL is ineffective")
 	}

splunknozzle/config.go

@@ -60,6 +60,7 @@ type Config struct {
 	StatusMonitorInterval     time.Duration `json:"mem-queue-monitor-interval"`
 	SelectedMonitoringMetrics string        `json:"selected-monitoring-metrics"`
 	SplunkMetricIndex         string        `json:"splunk-metric-index"`
+	MemoryBallastSize         int           `json:"memory-ballast-size"`
 }
 
 func NewConfigFromCmdFlags(version, branch, commit, buildos string) *Config {
@@ -150,6 +151,8 @@ func NewConfigFromCmdFlags(version, branch, commit, buildos string) *Config {
 		OverrideDefaultFromEnvar("SELECTED_MONITORING_METRICS").Default("nozzle.queue.percentage,splunk.events.dropped.count,splunk.events.sent.count,firehose.events.dropped.count,firehose.events.received.count,splunk.events.throughput,nozzle.usage.ram,nozzle.usage.cpu,nozzle.cache.memory.hit,nozzle.cache.memory.miss,nozzle.cache.remote.hit,nozzle.cache.remote.miss,nozzle.cache.boltdb.hit,nozzle.cache.boltdb.miss").StringVar(&c.SelectedMonitoringMetrics)
 	kingpin.Flag("splunk-metric-index", "Splunk metric index").
 		OverrideDefaultFromEnvar("SPLUNK_METRIC_INDEX").StringVar(&c.SplunkMetricIndex)
+	kingpin.Flag("memory-ballast-size", "Size of ballast in MB").
+		OverrideDefaultFromEnvar("MEMORY_BALLAST_SIZE").Default("0").IntVar(&c.MemoryBallastSize)
 
 	kingpin.Parse()
 	c.ApiEndpoint = strings.TrimSpace(c.ApiEndpoint)

splunknozzle/config_test.go

@@ -65,6 +65,7 @@ var _ = Describe("Config", func() {
 			os.Setenv("ENABLE_EVENT_TRACING", "true")
 			os.Setenv("DEBUG", "true")
 			os.Setenv("DROP_WARN_THRESHOLD", "100")
+			os.Setenv("MEMORY_BALLAST_SIZE", "512")
 
 			c := NewConfigFromCmdFlags(version, branch, commit, buildos)
 
@@ -110,6 +111,7 @@ var _ = Describe("Config", func() {
 
 			Expect(c.TraceLogging).To(BeTrue())
 			Expect(c.Debug).To(BeTrue())
+			Expect(c.MemoryBallastSize).To(Equal(512))
 		})
 
 		It("check defaults", func() {
@@ -141,6 +143,7 @@ var _ = Describe("Config", func() {
 
 			Expect(c.TraceLogging).To(BeFalse())
 			Expect(c.Debug).To(BeFalse())
+			Expect(c.MemoryBallastSize).To(Equal(0))
 		})
 	})
 
@@ -187,6 +190,7 @@ var _ = Describe("Config", func() {
 				"--enable-event-tracing",
 				"--debug",
 				"--splunk-metric-index=metric",
+				"--memory-ballast-size=512",
 			}
 			os.Args = args
 		})
@@ -230,6 +234,8 @@ var _ = Describe("Config", func() {
 
 			Expect(c.Debug).To(BeTrue())
 			Expect(c.TraceLogging).To(BeTrue())
+			Expect(c.MemoryBallastSize).To(Equal(512))
+
 			Expect(c.Version).To(Equal(version))
 			Expect(c.Branch).To(Equal(branch))
 			Expect(c.Commit).To(Equal(commit))

tile/tile.yml

@@ -272,6 +272,11 @@ forms:
         label: Keep alive timer
         description: Interval used to close and refresh connection to Splunk
         optional: true
+      - name: memory_ballast_size
+        type: integer
+        label: Memory Ballast Size
+        default: 0
+        description: Size of memory allocated to reduce GC cycles. Default is 0, Size should be less than the total memory.
 
 migration: |
   if (typeof properties['properties']['.properties.add_app_info']['value'] == "boolean") {