Making GC related fields tunable

client/client.go

@@ -225,10 +225,18 @@ func NewClient(cfg *config.Config, consulSyncer *consul.Syncer, logger *log.Logg
 		return nil, fmt.Errorf("failed to initialize client: %v", err)
 	}
 
-	// Add the stats collector and the garbage collector
+	// Add the stats collector
 	statsCollector := stats.NewHostStatsCollector(logger, c.config.AllocDir)
 	c.hostStatsCollector = statsCollector
-	c.garbageCollector = NewAllocGarbageCollector(logger, statsCollector, cfg.Node.Reserved.DiskMB)
+
+	// Add the garbage collector
+	gcConfig := &GCConfig{
+		DiskUsageThreshold:  cfg.GCDiskUsageThreshold,
+		InodeUsageThreshold: cfg.GCInodeUsageThreshold,
+		Interval:            cfg.GCInterval,
+		ReservedDiskMB:      cfg.Node.Reserved.DiskMB,
+	}
+	c.garbageCollector = NewAllocGarbageCollector(logger, statsCollector, gcConfig)
 
 	// Setup the node
 	if err := c.setupNode(); err != nil {

client/config/config.go

@@ -151,6 +151,18 @@ type Config struct {
 	// TLSConfig holds various TLS related configurations
 	TLSConfig *config.TLSConfig
 
+	// GCInterval is the time interval at which the client triggers garbage
+	// collection
+	GCInterval time.Duration
+
+	// GCDiskUsageThreshold is the disk usage threshold beyond which the Nomad
+	// client triggers GC of terminal allocations
+	GCDiskUsageThreshold float64
+
+	// GCInodeUsageThreshold is the inode usage threshold beyond which the Nomad
+	// client triggers GC of the terminal allocations
+	GCInodeUsageThreshold float64
+
 	// LogLevel is the level of the logs to putout
 	LogLevel string
 }
@@ -177,6 +189,9 @@ func DefaultConfig() *Config {
 		StatsCollectionInterval: 1 * time.Second,
 		TLSConfig:               &config.TLSConfig{},
 		LogLevel:                "DEBUG",
+		GCInterval:              1 * time.Minute,
+		GCDiskUsageThreshold:    80,
+		GCInodeUsageThreshold:   70,
 	}
 }
 

client/gc.go

@@ -12,18 +12,6 @@ import (
 )
 
 const (
-	// diskUsageThreshold is the percent of used disk space beyond which Nomad
-	// GCs terminated allocations
-	diskUsageThreshold = 80
-
-	// gcInterval is the interval at which Nomad runs the garbage collector
-	gcInterval = 1 * time.Minute
-
-	// inodeUsageThreshold is the percent of inode usage that Nomad tries to
-	// maintain, whenever we are over it we will attempt to GC terminal
-	// allocations
-	inodeUsageThreshold = 70
-
 	// MB is a constant which converts values in bytes to MB
 	MB = 1024 * 1024
 )
@@ -134,22 +122,30 @@ func (i *IndexedGCAllocPQ) Length() int {
 	return len(i.heap)
 }
 
+// GCConfig allows changing the behaviour of the garbage collector
+type GCConfig struct {
+	DiskUsageThreshold  float64
+	InodeUsageThreshold float64
+	Interval            time.Duration
+	ReservedDiskMB      int
+}
+
 // AllocGarbageCollector garbage collects terminated allocations on a node
 type AllocGarbageCollector struct {
 	allocRunners   *IndexedGCAllocPQ
 	statsCollector stats.NodeStatsCollector
-	reservedDiskMB int
+	config         *GCConfig
 	logger         *log.Logger
 	shutdownCh     chan struct{}
 }
 
 // NewAllocGarbageCollector returns a garbage collector for terminated
 // allocations on a node.
-func NewAllocGarbageCollector(logger *log.Logger, statsCollector stats.NodeStatsCollector, reservedDiskMB int) *AllocGarbageCollector {
+func NewAllocGarbageCollector(logger *log.Logger, statsCollector stats.NodeStatsCollector, config *GCConfig) *AllocGarbageCollector {
 	gc := &AllocGarbageCollector{
 		allocRunners:   NewIndexedGCAllocPQ(),
 		statsCollector: statsCollector,
-		reservedDiskMB: reservedDiskMB,
+		config:         config,
 		logger:         logger,
 		shutdownCh:     make(chan struct{}),
 	}
@@ -159,7 +155,7 @@ func NewAllocGarbageCollector(logger *log.Logger, statsCollector stats.NodeStats
 }
 
 func (a *AllocGarbageCollector) run() {
-	ticker := time.NewTicker(gcInterval)
+	ticker := time.NewTicker(a.config.Interval)
 	for {
 		select {
 		case <-ticker.C:
@@ -195,8 +191,8 @@ func (a *AllocGarbageCollector) keepUsageBelowThreshold() error {
 			break
 		}
 
-		if diskStats.UsedPercent <= diskUsageThreshold &&
-			diskStats.InodesUsedPercent <= inodeUsageThreshold {
+		if diskStats.UsedPercent <= a.config.DiskUsageThreshold &&
+			diskStats.InodesUsedPercent <= a.config.InodeUsageThreshold {
 			break
 		}
 
@@ -266,10 +262,10 @@ func (a *AllocGarbageCollector) MakeRoomFor(allocations []*structs.Allocation) e
 	// we don't need to garbage collect terminated allocations
 	if hostStats := a.statsCollector.Stats(); hostStats != nil {
 		var availableForAllocations uint64
-		if hostStats.AllocDirStats.Available < uint64(a.reservedDiskMB*MB) {
+		if hostStats.AllocDirStats.Available < uint64(a.config.ReservedDiskMB*MB) {
 			availableForAllocations = 0
 		} else {
-			availableForAllocations = hostStats.AllocDirStats.Available - uint64(a.reservedDiskMB*MB)
+			availableForAllocations = hostStats.AllocDirStats.Available - uint64(a.config.ReservedDiskMB*MB)
 		}
 		if uint64(totalResource.DiskMB*MB) < availableForAllocations {
 			return nil

command/agent/agent.go

@@ -288,6 +288,11 @@ func (a *Agent) clientConfig() (*clientconfig.Config, error) {
 	conf.TLSConfig = a.config.TLSConfig
 	conf.Node.TLSEnabled = conf.TLSConfig.EnableHTTP
 
+	// Set the GC related configs
+	conf.GCInterval = a.config.Client.GCInterval
+	conf.GCDiskUsageThreshold = a.config.Client.GCDiskUsageThreshold
+	conf.GCInodeUsageThreshold = a.config.Client.GCInodeUsageThreshold
+
 	return conf, nil
 }
 

command/agent/config-test-fixtures/basic.hcl

@@ -53,6 +53,9 @@ client {
         data_points = 35
         collection_interval = "5s"
     }
+    gc_interval = "6s"
+    gc_disk_usage_threshold = 82
+    gc_inode_usage_threshold = 91
 }
 server {
 	enabled = true

command/agent/config.go

@@ -197,6 +197,18 @@ type ClientConfig struct {
 	// be used to target a certain utilization or to prevent Nomad from using a
 	// particular set of ports.
 	Reserved *Resources `mapstructure:"reserved"`
+
+	// GCInterval is the time interval at which the client triggers garbage
+	// collection
+	GCInterval time.Duration `mapstructure:"gc_interval"`
+
+	// GCInodeUsageThreshold is the inode usage threshold beyond which the Nomad
+	// client triggers GC of the terminal allocations
+	GCDiskUsageThreshold float64 `mapstructure:"gc_disk_usage_threshold"`
+
+	// GCInodeUsageThreshold is the inode usage threshold beyond which the Nomad
+	// client triggers GC of the terminal allocations
+	GCInodeUsageThreshold float64 `mapstructure:"gc_inode_usage_threshold"`
 }
 
 // ServerConfig is configuration specific to the server mode
@@ -465,6 +477,9 @@ func DevConfig() *Config {
 	conf.Client.Options = map[string]string{
 		"driver.docker.volumes": "true",
 	}
+	conf.Client.GCInterval = 10 * time.Minute
+	conf.Client.GCDiskUsageThreshold = 99
+	conf.Client.GCInodeUsageThreshold = 99
 
 	return conf
 }
@@ -487,11 +502,14 @@ func DefaultConfig() *Config {
 		Consul:         config.DefaultConsulConfig(),
 		Vault:          config.DefaultVaultConfig(),
 		Client: &ClientConfig{
-			Enabled:        false,
-			MaxKillTimeout: "30s",
-			ClientMinPort:  14000,
-			ClientMaxPort:  14512,
-			Reserved:       &Resources{},
+			Enabled:               false,
+			MaxKillTimeout:        "30s",
+			ClientMinPort:         14000,
+			ClientMaxPort:         14512,
+			Reserved:              &Resources{},
+			GCInterval:            1 * time.Minute,
+			GCInodeUsageThreshold: 70,
+			GCDiskUsageThreshold:  80,
 		},
 		Server: &ServerConfig{
 			Enabled:          false,

command/agent/config_parse.go

@@ -341,6 +341,9 @@ func parseClient(result **ClientConfig, list *ast.ObjectList) error {
 		"client_min_port",
 		"reserved",
 		"stats",
+		"gc_interval",
+		"gc_disk_usage_threshold",
+		"gc_inode_usage_threshold",
 	}
 	if err := checkHCLKeys(listVal, valid); err != nil {
 		return err
@@ -358,7 +361,15 @@ func parseClient(result **ClientConfig, list *ast.ObjectList) error {
 	delete(m, "stats")
 
 	var config ClientConfig
-	if err := mapstructure.WeakDecode(m, &config); err != nil {
+	dec, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
+		DecodeHook:       mapstructure.StringToTimeDurationHookFunc(),
+		WeaklyTypedInput: true,
+		Result:           &config,
+	})
+	if err != nil {
+		return err
+	}
+	if err := dec.Decode(m); err != nil {
 		return err
 	}
 

command/agent/config_parse_test.go

@@ -70,6 +70,9 @@ func TestConfig_Parse(t *testing.T) {
 						ReservedPorts:       "1,100,10-12",
 						ParsedReservedPorts: []int{1, 10, 11, 12, 100},
 					},
+					GCInterval:            6 * time.Second,
+					GCDiskUsageThreshold:  82,
+					GCInodeUsageThreshold: 91,
 				},
 				Server: &ServerConfig{
 					Enabled:           true,

scripts/build.sh

@@ -84,3 +84,4 @@ done
 echo
 echo "==> Results:"
 tree pkg/
+

website/source/docs/agent/configuration/client.html.md

@@ -83,6 +83,15 @@ client {
  [data_dir](/docs/agent/configuration/index.html#data_dir) suffixed with
  "client", like `"/opt/nomad/client"`. This must be an absolute path.
 
+- `gc_interval` `(string: "1m")` - Specifies the interval at which Nomad
+  attempts to garbage collect terminal allocation directories. 
+
+- `gc_disk_usage_threshold` `(float: 80)` - Specifies the disk usage percent which
+  Nomad tries to maintain by garbage collecting terminal allocations.
+
+- `gc_inode_usage_threshold` `(float: 70)` - Specifies the inode usage percent
+  which Nomad tries to maintain by garbage collecting terminal allocations.
+
 ### `chroot_env` Parameters
 
 Drivers based on [isolated fork/exec](/docs/drivers/exec.html) implement file