fix(snmp): fix data race in health status map (#1365)

* fix(snmp): fix data race in health status map

* perf(snmp): add load-first

---------

Co-authored-by: peter <>

Author: c88888

inputs/snmp/health_check.go

@@ -33,21 +33,24 @@ func (ins *Instance) StartHealthMonitor() {
 }
 
 func (ins *Instance) checkAgentHealth(i int, agent string) {
-	status, exists := ins.targetStatus[agent]
+	val, exists := ins.targetStatus.Load(agent)
 	if !exists {
-		ins.targetStatus[agent] = &TargetStatus{healthy: true, lastSeen: time.Now()}
-		status = ins.targetStatus[agent]
+		newStatus := &TargetStatus{
+			healthy:  true,
+			lastSeen: time.Now(),
+		}
+		val, _ = ins.targetStatus.LoadOrStore(agent, newStatus)
 	}
+	status := val.(*TargetStatus)
 
 	// Don't check too frequently if already marked as unhealthy
-	if !status.healthy {
-		status.mu.RLock()
-		timeSinceLastCheck := time.Since(status.lastSeen)
-		status.mu.RUnlock()
+	status.mu.RLock()
+	healthy := status.healthy
+	timeSinceLastCheck := time.Since(status.lastSeen)
+	status.mu.RUnlock()
 
-		if timeSinceLastCheck < time.Duration(ins.RecoveryInterval) {
-			return
-		}
+	if !healthy && timeSinceLastCheck < time.Duration(ins.RecoveryInterval) {
+		return
 	}
 
 	// Create a connection with shorter timeout for health checking
@@ -111,12 +114,22 @@ func (ins *Instance) checkAgentHealth(i int, agent string) {
 }
 
 func (ins *Instance) markAgentUnhealthy(agent string) {
-	status, exists := ins.targetStatus[agent]
+	val, exists := ins.targetStatus.Load(agent)
 	if !exists {
-		ins.targetStatus[agent] = &TargetStatus{healthy: false, lastSeen: time.Now(), failCount: ins.MaxFailCount}
-		return
+		newStatus := &TargetStatus{
+			healthy:   false,
+			lastSeen:  time.Now(),
+			failCount: ins.MaxFailCount,
+		}
+		var loaded bool
+		val, loaded = ins.targetStatus.LoadOrStore(agent, newStatus)
+		if !loaded {
+			return
+		}
 	}
 
+	// Existing status found, update it
+	status := val.(*TargetStatus)
 	status.mu.Lock()
 	defer status.mu.Unlock()
 
@@ -131,11 +144,13 @@ func (ins *Instance) markAgentUnhealthy(agent string) {
 }
 
 func (ins *Instance) isAgentHealthy(agent string) bool {
-	status, exists := ins.targetStatus[agent]
+	val, exists := ins.targetStatus.Load(agent)
 	if !exists {
 		return true // Default to considering it healthy if no status exists
 	}
 
+	// Existing status found, update it
+	status := val.(*TargetStatus)
 	status.mu.RLock()
 	defer status.mu.RUnlock()
 	return status.healthy

inputs/snmp/instances.go

@@ -54,7 +54,7 @@ type Instance struct {
 	Mappings map[string]map[string]string `toml:"mappings"`
 
 	// Track health status of each agent
-	targetStatus         map[string]*TargetStatus
+	targetStatus         sync.Map // key: agent string, value: *TargetStatus
 	targetStatusInit     sync.Once
 	healthMonitorStarted bool
 
@@ -120,12 +120,11 @@ func (ins *Instance) Init() error {
 
 	// Initialize target status tracking
 	ins.targetStatusInit.Do(func() {
-		ins.targetStatus = make(map[string]*TargetStatus)
 		for _, agent := range ins.Agents {
-			ins.targetStatus[agent] = &TargetStatus{
+			ins.targetStatus.Store(agent, &TargetStatus{
 				healthy:  true,
 				lastSeen: time.Now(),
-			}
+			})
 		}
 	})
 
@@ -215,7 +214,8 @@ func (ins *Instance) Gather(slist *types.SampleList) {
 			if m, ok := ins.Mappings[agent]; ok {
 				extraTags = m
 			}
-			if status, exists := ins.targetStatus[agent]; exists {
+			if val, exists := ins.targetStatus.Load(agent); exists {
+				status := val.(*TargetStatus)
 				status.mu.Lock()
 				status.healthy = true
 				status.failCount = 0