diff --git a/src/collector/collector.go b/src/collector/collector.go
index a41456152b8a751efa1b3f55d14ea4814ee2b476..6963f0a41ce040c252dfe32d9464c9202630b550 100644
--- a/src/collector/collector.go
+++ b/src/collector/collector.go
@@ -2,8 +2,13 @@
 package collector
 
 import (
+	"context"
 	"log"
 	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
 
 	config "csudata.com/zqpool/src/config"
 	"github.com/prometheus/client_golang/prometheus"
@@ -113,12 +118,32 @@ func IncreaseBackendConnectionLimitReachedTimes(labelValue string) {
 }
 
 func StartPromServer() {
+	_, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
 	port := config.Get("exporter_port")
 	if port == "" {
 		log.Println("exporter_port not set in configuration, set port of Exporter to '9816'.")
 		port = "9816"
 	}
 
-	http.Handle("/metrics", promhttp.Handler())
-	log.Fatal(http.ListenAndServe(":"+port, nil))
+	srv := &http.Server{
+		Addr:    ":" + port,
+		Handler: promhttp.Handler(),
+	}
+
+	sigint := make(chan os.Signal, 1)
+	signal.Notify(sigint, syscall.SIGINT, syscall.SIGTERM)
+
+	go func() {
+		<-sigint
+		cancel()
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		if err := srv.Shutdown(ctx); err != nil {
+			// 如果 Shutdown 不成功，就强制关闭
+			log.Printf("Server forced to shutdown: %v", err)
+		}
+	}()
+	log.Fatal(srv.ListenAndServe())
 }
diff --git a/src/poolserver/fe_be_logic.go b/src/poolserver/fe_be_logic.go
index 694988c17321d2b24ad42a7ac9b5d86421aebc39..76a49817a089e6e8811d0432ecae0a6c3bb6f762 100644
--- a/src/poolserver/fe_be_logic.go
+++ b/src/poolserver/fe_be_logic.go
@@ -234,6 +234,10 @@ func (ctx *ConnContext) forwardToClient() (error, error) {
 			zap.S().Infof("Client(%d): RB(%d): ERROR: %s", ctx.Pid, ctx.pBackConn.Id, backendErr.Error())
 			ctx.cliConn.Close()
 			ctx.BeReconnect()
+
+			zap.S().Debugf("Client(%d): release backend(%d)", ctx.Pid, ctx.pBackConn.Id)
+			atomic.StoreInt32(&ctx.pBackConn.State, 0)
+			ctx.isGetBackend = false
 			return nil, backendErr
 		}
 		pos += n
@@ -245,6 +249,10 @@ func (ctx *ConnContext) forwardToClient() (error, error) {
 			zap.S().Infof("Client(%d): SC: ERROR: %s", ctx.Pid, clientErr.Error())
 			ctx.cliConn.Close()
 			ctx.BeReconnect()
+
+			zap.S().Debugf("Client(%d): release backend(%d)", ctx.Pid, ctx.pBackConn.Id)
+			atomic.StoreInt32(&ctx.pBackConn.State, 0)
+			ctx.isGetBackend = false
 			return clientErr, nil
 		}