Merge pull request #2427 from hashicorp/f-gc-limit

Limit parallelism during garbage collection

command/agent/agent.go

@@ -310,6 +310,7 @@ func (a *Agent) clientConfig() (*clientconfig.Config, error) {
 
 	// Set the GC related configs
 	conf.GCInterval = a.config.Client.GCInterval
+	conf.GCParallelDestroys = a.config.Client.GCParallelDestroys
 	conf.GCDiskUsageThreshold = a.config.Client.GCDiskUsageThreshold
 	conf.GCInodeUsageThreshold = a.config.Client.GCInodeUsageThreshold
 	conf.NoHostUUID = a.config.Client.NoHostUUID

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

@@ -54,6 +54,7 @@ client {
         collection_interval = "5s"
     }
     gc_interval = "6s"
+    gc_parallel_destroys = 6
     gc_disk_usage_threshold = 82
     gc_inode_usage_threshold = 91
     no_host_uuid = true

command/agent/config.go

@@ -202,6 +202,10 @@ type ClientConfig struct {
 	// collection
 	GCInterval time.Duration `mapstructure:"gc_interval"`
 
+	// GCParallelDestroys is the number of parallel destroys the garbage
+	// collector will allow.
+	GCParallelDestroys int `mapstructure:"gc_parallel_destroys"`
+
 	// GCInodeUsageThreshold is the inode usage threshold beyond which the Nomad
 	// client triggers GC of the terminal allocations
 	GCDiskUsageThreshold float64 `mapstructure:"gc_disk_usage_threshold"`
@@ -524,6 +528,7 @@ func DefaultConfig() *Config {
 			ClientMaxPort:         14512,
 			Reserved:              &Resources{},
 			GCInterval:            1 * time.Minute,
+			GCParallelDestroys:    2,
 			GCInodeUsageThreshold: 70,
 			GCDiskUsageThreshold:  80,
 		},
@@ -929,6 +934,9 @@ func (a *ClientConfig) Merge(b *ClientConfig) *ClientConfig {
 	if b.GCInterval != 0 {
 		result.GCInterval = b.GCInterval
 	}
+	if b.GCParallelDestroys != 0 {
+		result.GCParallelDestroys = b.GCParallelDestroys
+	}
 	if b.GCDiskUsageThreshold != 0 {
 		result.GCDiskUsageThreshold = b.GCDiskUsageThreshold
 	}

command/agent/config_parse.go

@@ -344,6 +344,7 @@ func parseClient(result **ClientConfig, list *ast.ObjectList) error {
 		"gc_interval",
 		"gc_disk_usage_threshold",
 		"gc_inode_usage_threshold",
+		"gc_parallel_destroys",
 		"no_host_uuid",
 	}
 	if err := checkHCLKeys(listVal, valid); err != nil {

command/agent/config_parse_test.go

@@ -71,6 +71,7 @@ func TestConfig_Parse(t *testing.T) {
 						ParsedReservedPorts: []int{1, 10, 11, 12, 100},
 					},
 					GCInterval:            6 * time.Second,
+					GCParallelDestroys:    6,
 					GCDiskUsageThreshold:  82,
 					GCInodeUsageThreshold: 91,
 					NoHostUUID:            true,

command/agent/config_test.go

@@ -212,6 +212,7 @@ func TestConfig_Merge(t *testing.T) {
 				ParsedReservedPorts: []int{1, 2, 3},
 			},
 			GCInterval:            6 * time.Second,
+			GCParallelDestroys:    6,
 			GCDiskUsageThreshold:  71,
 			GCInodeUsageThreshold: 86,
 		},