address review comments

chain/consensus/compute_state.go

@@ -196,6 +196,7 @@ func (t *TipSetExecutor) ApplyBlocks(ctx context.Context,
 	cronGas = 0
 	partDone = metrics.Timer(ctx, metrics.VMApplyMessages)
 
+	// TODO reorg the code to minimize the execution critical section
 	vmi, err := makeVm(pstate, epoch, ts.MinTimestamp())
 	if err != nil {
 		return cid.Undef, cid.Undef, xerrors.Errorf("making vm: %w", err)

chain/gen/genesis/miners.go

@@ -108,6 +108,7 @@ func SetupStorageMiners(ctx context.Context, cs *store.ChainStore, sys vm.Syscal
 	if err != nil {
 		return cid.Undef, fmt.Errorf("creating vm: %w", err)
 	}
+	// Note: genesisVm is mutated, so this has to happen in a deferred func; go horror show.
 	defer func() { genesisVm.Done() }()
 
 	if len(miners) == 0 {

chain/stmgr/call.go

@@ -159,6 +159,7 @@ func (sm *StateManager) callInternal(ctx context.Context, msg *types.Message, pr
 	if err != nil {
 		return nil, xerrors.Errorf("failed to set up vm: %w", err)
 	}
+	// Note: vmi is mutated, so this has to happen in a deferred func; go horror show.
 	defer func() { vmi.Done() }()
 
 	for i, m := range priorMsgs {

chain/vm/execution.go

@@ -17,8 +17,14 @@ import (
 )
 
 const (
+	// DefaultAvailableExecutionLanes is the number of available execution lanes; it is the bound of
+	// concurrent active executions.
+	// This is the default value in filecoin-ffi
 	DefaultAvailableExecutionLanes = 4
-	DefaultPriorityExecutionLanes  = 2
+	// DefaultPriorityExecutionLanes is the number of reserved execution lanes for priority computations.
+	// This is purely userspace, but we believe it is a reasonable default, even with more available
+	// lanes.
+	DefaultPriorityExecutionLanes = 2
 )
 
 var ErrExecutorDone = errors.New("executor has been released")
@@ -118,7 +124,7 @@ func (e *executionEnv) getToken(lane ExecutionLane) *executionToken {
 
 		e.available--
 
-		metricsUp(metrics.VMExecutionActive, lane)
+		metricsUp(metrics.VMExecutionRunning, lane)
 		return &executionToken{lane: lane, reserved: 0}
 
 	case ExecutionLanePriority:
@@ -134,7 +140,7 @@ func (e *executionEnv) getToken(lane ExecutionLane) *executionToken {
 			reserving = 1
 		}
 
-		metricsUp(metrics.VMExecutionActive, lane)
+		metricsUp(metrics.VMExecutionRunning, lane)
 		return &executionToken{lane: lane, reserved: reserving}
 
 	default:
@@ -152,7 +158,7 @@ func (e *executionEnv) putToken(token *executionToken) {
 
 	e.cond.Broadcast()
 
-	metricsDown(metrics.VMExecutionActive, token.lane)
+	metricsDown(metrics.VMExecutionRunning, token.lane)
 }
 
 func metricsUp(metric *stats.Int64Measure, lane ExecutionLane) {

chain/vm/vmi.go

@@ -37,7 +37,7 @@ type Interface interface {
 	Flush(ctx context.Context) (cid.Cid, error)
 }
 
-// Executor is the general vm execution interface, which is prioritized according to execution langes.
+// Executor is the general vm execution interface, which is prioritized according to execution lanes.
 // User must call Done when it is done with this executor to release resource holds by the execution
 // environment
 type Executor interface {

metrics/metrics.go

@@ -125,7 +125,7 @@ var (
 	VMSends                             = stats.Int64("vm/sends", "Counter for sends processed by the VM", stats.UnitDimensionless)
 	VMApplied                           = stats.Int64("vm/applied", "Counter for messages (including internal messages) processed by the VM", stats.UnitDimensionless)
 	VMExecutionWaiting                  = stats.Int64("vm/execution_waiting", "Counter for VM executions waiting to be assigned to a lane", stats.UnitDimensionless)
-	VMExecutionActive                   = stats.Int64("vm/execution_default", "Counter for active VM executions", stats.UnitDimensionless)
+	VMExecutionRunning                  = stats.Int64("vm/execution_running", "Counter for running VM executions", stats.UnitDimensionless)
 
 	// miner
 	WorkerCallsStarted           = stats.Int64("sealing/worker_calls_started", "Counter of started worker tasks", stats.UnitDimensionless)
@@ -373,8 +373,8 @@ var (
 		Aggregation: view.LastValue(),
 		TagKeys:     []tag.Key{ExecutionLane},
 	}
-	VMExecutionActiveView = &view.View{
+	VMExecutionRunningView = &view.View{
-		Measure:     VMExecutionActive,
+		Measure:     VMExecutionRunning,
 		Aggregation: view.LastValue(),
 		TagKeys:     []tag.Key{ExecutionLane},
 	}