debug.go

Documentation: github.com/rcrowley/go-metrics

     1  package metrics
     2  
     3  import (
     4  	"runtime/debug"
     5  	"sync"
     6  	"time"
     7  )
     8  
     9  var (
    10  	debugMetrics struct {
    11  		GCStats struct {
    12  			LastGC Gauge
    13  			NumGC  Gauge
    14  			Pause  Histogram
    15  			//PauseQuantiles Histogram
    16  			PauseTotal Gauge
    17  		}
    18  		ReadGCStats Timer
    19  	}
    20  	gcStats                  debug.GCStats
    21  	registerDebugMetricsOnce = sync.Once{}
    22  )
    23  
    24  // Capture new values for the Go garbage collector statistics exported in
    25  // debug.GCStats.  This is designed to be called as a goroutine.
    26  func CaptureDebugGCStats(r Registry, d time.Duration) {
    27  	for _ = range time.Tick(d) {
    28  		CaptureDebugGCStatsOnce(r)
    29  	}
    30  }
    31  
    32  // Capture new values for the Go garbage collector statistics exported in
    33  // debug.GCStats.  This is designed to be called in a background goroutine.
    34  // Giving a registry which has not been given to RegisterDebugGCStats will
    35  // panic.
    36  //
    37  // Be careful (but much less so) with this because debug.ReadGCStats calls
    38  // the C function runtime·lock(runtime·mheap) which, while not a stop-the-world
    39  // operation, isn't something you want to be doing all the time.
    40  func CaptureDebugGCStatsOnce(r Registry) {
    41  	lastGC := gcStats.LastGC
    42  	t := time.Now()
    43  	debug.ReadGCStats(&gcStats)
    44  	debugMetrics.ReadGCStats.UpdateSince(t)
    45  
    46  	debugMetrics.GCStats.LastGC.Update(int64(gcStats.LastGC.UnixNano()))
    47  	debugMetrics.GCStats.NumGC.Update(int64(gcStats.NumGC))
    48  	if lastGC != gcStats.LastGC && 0 < len(gcStats.Pause) {
    49  		debugMetrics.GCStats.Pause.Update(int64(gcStats.Pause[0]))
    50  	}
    51  	//debugMetrics.GCStats.PauseQuantiles.Update(gcStats.PauseQuantiles)
    52  	debugMetrics.GCStats.PauseTotal.Update(int64(gcStats.PauseTotal))
    53  }
    54  
    55  // Register metrics for the Go garbage collector statistics exported in
    56  // debug.GCStats.  The metrics are named by their fully-qualified Go symbols,
    57  // i.e. debug.GCStats.PauseTotal.
    58  func RegisterDebugGCStats(r Registry) {
    59  	registerDebugMetricsOnce.Do(func() {
    60  		debugMetrics.GCStats.LastGC = NewGauge()
    61  		debugMetrics.GCStats.NumGC = NewGauge()
    62  		debugMetrics.GCStats.Pause = NewHistogram(NewExpDecaySample(1028, 0.015))
    63  		//debugMetrics.GCStats.PauseQuantiles = NewHistogram(NewExpDecaySample(1028, 0.015))
    64  		debugMetrics.GCStats.PauseTotal = NewGauge()
    65  		debugMetrics.ReadGCStats = NewTimer()
    66  
    67  		r.Register("debug.GCStats.LastGC", debugMetrics.GCStats.LastGC)
    68  		r.Register("debug.GCStats.NumGC", debugMetrics.GCStats.NumGC)
    69  		r.Register("debug.GCStats.Pause", debugMetrics.GCStats.Pause)
    70  		//r.Register("debug.GCStats.PauseQuantiles", debugMetrics.GCStats.PauseQuantiles)
    71  		r.Register("debug.GCStats.PauseTotal", debugMetrics.GCStats.PauseTotal)
    72  		r.Register("debug.ReadGCStats", debugMetrics.ReadGCStats)
    73  	})
    74  }
    75  
    76  // Allocate an initial slice for gcStats.Pause to avoid allocations during
    77  // normal operation.
    78  func init() {
    79  	gcStats.Pause = make([]time.Duration, 11)
    80  }
    81
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