Move runtime metrics reporting to a separate timer routine.

config.go

@@ -28,6 +28,7 @@ type Config struct {
 	OmitEmptyHostname             bool      `yaml:"omit_empty_hostname"`
 	Percentiles                   []float64 `yaml:"percentiles"`
 	ReadBufferSizeBytes           int       `yaml:"read_buffer_size_bytes"`
+	RuntimeMetricsFlushInterval   string    `yaml:"runtime_metrics_flush_interval"`
 	SentryDsn                     string    `yaml:"sentry_dsn"`
 	SsfAddress                    string    `yaml:"ssf_address"`
 	SsfBufferSize                 int       `yaml:"ssf_buffer_size"`

config_parse.go

@@ -6,7 +6,6 @@ import (
 	"io/ioutil"
 	"net/url"
 	"os"
-	"time"
 
 	"github.com/kelseyhightower/envconfig"
 
@@ -137,10 +136,10 @@ func readConfig(r io.Reader) (c Config, err error) {
 	}
 	c.SsfListenAddresses = append(c.SsfListenAddresses, ssfAddrs...)
 
-	return c, nil
-}
+	if c.RuntimeMetricsFlushInterval == "" {
+		// Default the runtime metrics to the flush interval if not overriden
+		c.RuntimeMetricsFlushInterval = c.Interval
+	}
 
-// ParseInterval handles parsing the flush interval as a time.Duration
-func (c Config) ParseInterval() (time.Duration, error) {
-	return time.ParseDuration(c.Interval)
+	return c, nil
 }

config_test.go

@@ -22,7 +22,7 @@ func TestReadConfig(t *testing.T) {
 	assert.Equal(t, "https://app.datadoghq.com", c.DatadogAPIHostname)
 	assert.Equal(t, 96, c.NumWorkers)
 
-	interval, err := c.ParseInterval()
+	interval, err := time.ParseDuration(c.Interval)
 	assert.NoError(t, err)
 	assert.Equal(t, interval, 10*time.Second)
 

example.yaml

@@ -105,7 +105,6 @@ num_workers: 96
 num_readers: 1
 
 
-
 # == LIMITS ==
 
 # How big of a buffer to allocate for incoming metrics. Metrics longer than this
@@ -127,7 +126,6 @@ read_buffer_size_bytes: 2097152
 # will post multiple times in parallel if the limit is exceeded.
 flush_max_per_body: 25000
 
-
 # == DIAGNOSTICS ==
 
 # Sets the log level to DEBUG
@@ -139,6 +137,9 @@ sentry_dsn: ""
 # Enables Go profiling
 enable_profiling: false
 
+# Veneur emits metrics about itself. By default it matches the `interval`, but
+# you can tune it to a different interval if desired.
+runtime_metrics_flush_interval: "10s"
 
 
 # == SINKS ==

flusher.go

@@ -10,7 +10,6 @@ import (
 	"net"
 	"net/http"
 	"net/url"
-	"runtime"
 	"time"
 
 	"github.com/DataDog/datadog-go/statsd"
@@ -26,13 +25,6 @@ func (s *Server) Flush() {
 	span := tracer.StartSpan("flush").(*trace.Span)
 	defer span.Finish()
 
-	mem := &runtime.MemStats{}
-	runtime.ReadMemStats(mem)
-
-	s.Statsd.Gauge("mem.heap_alloc_bytes", float64(mem.HeapAlloc), nil, 1.0)
-	s.Statsd.Gauge("gc.number", float64(mem.NumGC), nil, 1.0)
-	s.Statsd.Gauge("gc.pause_total_ns", float64(mem.PauseTotalNs), nil, 1.0)
-
 	// right now we have only one destination plugin
 	// but eventually, this is where we would loop over our supported
 	// destinations

server.go

@@ -11,6 +11,7 @@ import (
 	"io"
 	"net"
 	"net/http"
+	"runtime"
 	"strings"
 	"sync"
 	"syscall"
@@ -87,10 +88,11 @@ type Server struct {
 	SSFListenAddrs    []net.Addr
 	RcvbufBytes       int
 
-	interval            time.Duration
-	numReaders          int
-	metricMaxLength     int
-	traceMaxLengthBytes int
+	interval              time.Duration
+	runtimeMetricInterval time.Duration
+	numReaders            int
+	metricMaxLength       int
+	traceMaxLengthBytes   int
 
 	tlsConfig      *tls.Config
 	tcpReadTimeout time.Duration
@@ -146,6 +148,12 @@ func NewFromConfig(conf Config) (ret Server, err error) {
 	if err != nil {
 		return
 	}
+
+	ret.runtimeMetricInterval, err = time.ParseDuration(conf.RuntimeMetricsFlushInterval)
+	if err != nil {
+		return
+	}
+
 	ret.HTTPClient = &http.Client{
 		// make sure that POSTs to datadog do not overflow the flush interval
 		Timeout: ret.interval * 9 / 10,
@@ -429,6 +437,30 @@ func (s *Server) Start() {
 		logrus.Info("Tracing sockets are configured - not reading trace socket")
 	}
 
+	// Emit runtime metrics about ourselves on a timer.
+	go func() {
+		defer func() {
+			ConsumePanic(s.Sentry, s.Statsd, s.Hostname, recover())
+		}()
+		ticker := time.NewTicker(s.runtimeMetricInterval)
+		for {
+			select {
+			case <-s.shutdown:
+				// stop flushing on graceful shutdown
+				ticker.Stop()
+				return
+			case <-ticker.C:
+				mem := &runtime.MemStats{}
+				runtime.ReadMemStats(mem)
+
+				s.Statsd.Gauge("mem.heap_alloc_bytes", float64(mem.HeapAlloc), nil, 1.0)
+				s.Statsd.Gauge("gc.number", float64(mem.NumGC), nil, 1.0)
+				s.Statsd.Gauge("gc.pause_total_ns", float64(mem.PauseTotalNs), nil, 1.0)
+				s.Statsd.Gauge("goroutines", float64(runtime.NumGoroutine()), nil, 1.0)
+			}
+		}
+	}()
+
 	// Flush every Interval forever!
 	go func() {
 		defer func() {

server_test.go

@@ -76,7 +76,8 @@ func generateConfig(forwardAddr string) Config {
 		Hostname:           "localhost",
 
 		// Use a shorter interval for tests
-		Interval:              DefaultFlushInterval.String(),
+		Interval:                    DefaultFlushInterval.String(),
+		RuntimeMetricsFlushInterval: DefaultFlushInterval.String(),
 		Key:                   "",
 		MetricMaxLength:       4096,
 		Percentiles:           []float64{.5, .75, .99},
@@ -189,7 +190,7 @@ type fixture struct {
 }
 
 func newFixture(t *testing.T, config Config) *fixture {
-	interval, err := config.ParseInterval()
+	interval, err := time.ParseDuration(config.Interval)
 	assert.NoError(t, err)
 
 	// Set up a remote server (the API that we're sending the data to)