pool/pool.go

@@ -107,7 +107,7 @@ var errPoolClientUnhealthy = errors.New("pool client unhealthy")
 type clientStatusMonitor struct {
 	logger         *zap.Logger
 	addr           string
-	healthy        *atomic.Bool
+	healthy        *atomic.Uint32
 	errorThreshold uint32
 
 	mu                sync.RWMutex // protect counters
@@ -116,6 +116,22 @@ type clientStatusMonitor struct {
 	methods           []*methodStatus
 }
 
+// values for healthy status of clientStatusMonitor.
+const (
+	// statusUnhealthyOnDial is set when dialing to the endpoint is failed,
+	// so there is no connection to the endpoint, and pool should not close it
+	// before re-establishing connection once again.
+	statusUnhealthyOnDial = iota
+
+	// statusUnhealthyOnRequest is set when communication after dialing to the
+	// endpoint is failed due to immediate or accumulated errors, connection is
+	// available and pool should close it before re-establishing connection once again.
+	statusUnhealthyOnRequest
+
+	// statusHealthy is set when connection is ready to be used by the pool.
+	statusHealthy
+)
+
 // methodStatus provide statistic for specific method.
 type methodStatus struct {
 	name string
@@ -197,8 +213,8 @@ func newClientStatusMonitor(logger *zap.Logger, addr string, errorThreshold uint
 		methods[i] = &methodStatus{name: i.String()}
 	}
 
-	healthy := new(atomic.Bool)
-	healthy.Store(true)
+	healthy := new(atomic.Uint32)
+	healthy.Store(statusHealthy)
 
 	return clientStatusMonitor{
 		logger:         logger,
@@ -324,7 +340,7 @@ func (c *clientWrapper) dial(ctx context.Context) error {
 	prmDial.SetGRPCDialOptions(c.prm.dialOptions...)
 
 	if err = cl.Dial(ctx, prmDial); err != nil {
-		c.setUnhealthy()
+		c.setUnhealthyOnDial()
 		return err
 	}
 
@@ -341,6 +357,12 @@ func (c *clientWrapper) restartIfUnhealthy(ctx context.Context) (healthy, change
 		wasHealthy = true
 	}
 
+	// if connection is dialed before, to avoid routine / connection leak,
+	// pool has to close it and then initialize once again.
+	if c.isDialed() {
+		_ = c.close()
+	}
+
 	var cl sdkClient.Client
 	var prmInit sdkClient.PrmInit
 	prmInit.SetDefaultPrivateKey(c.prm.key)
@@ -355,7 +377,7 @@ func (c *clientWrapper) restartIfUnhealthy(ctx context.Context) (healthy, change
 	prmDial.SetGRPCDialOptions(c.prm.dialOptions...)
 
 	if err := cl.Dial(ctx, prmDial); err != nil {
-		c.setUnhealthy()
+		c.setUnhealthyOnDial()
 		return false, wasHealthy
 	}
 
@@ -1008,15 +1030,23 @@ func (c *clientWrapper) sessionCreate(ctx context.Context, prm prmCreateSession)
 }
 
 func (c *clientStatusMonitor) isHealthy() bool {
-	return c.healthy.Load()
+	return c.healthy.Load() == statusHealthy
+}
+
+func (c *clientStatusMonitor) isDialed() bool {
+	return c.healthy.Load() != statusUnhealthyOnDial
 }
 
 func (c *clientStatusMonitor) setHealthy() {
-	c.healthy.Store(true)
+	c.healthy.Store(statusHealthy)
 }
 
 func (c *clientStatusMonitor) setUnhealthy() {
-	c.healthy.Store(false)
+	c.healthy.Store(statusUnhealthyOnRequest)
+}
+
+func (c *clientStatusMonitor) setUnhealthyOnDial() {
+	c.healthy.Store(statusUnhealthyOnDial)
 }
 
 func (c *clientStatusMonitor) address() string {