diff --git a/kernel/server/port.go b/kernel/server/port.go
new file mode 100644
index 000000000..d4814516d
--- /dev/null
+++ b/kernel/server/port.go
@@ -0,0 +1,154 @@
+// SiYuan - Build Your Eternal Digital Garden
+// Copyright (c) 2020-present, b3log.org
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package server
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/88250/gulu"
+	goPS "github.com/mitchellh/go-ps"
+	"github.com/siyuan-note/logging"
+	"github.com/siyuan-note/siyuan/kernel/util"
+)
+
+func killRunningKernel() {
+	defer logging.Recover()
+
+	if "dev" == util.Mode {
+		return
+	}
+
+	if util.ContainerStd != util.Container {
+		return
+	}
+
+	processes, err := goPS.Processes()
+	if nil != err {
+		logging.LogErrorf("get processes failed: %s", err)
+		killByPort(util.FixedPort)
+		return
+	}
+
+	killed := false
+	for _, process := range processes {
+		procName := strings.ToLower(process.Executable())
+		if strings.Contains(procName, "siyuan-kernel") {
+			kill(fmt.Sprintf("%d", process.Pid()))
+			killed = true
+		}
+	}
+
+	if killed {
+		portJSON := filepath.Join(util.HomeDir, ".config", "siyuan", "port.json")
+		os.RemoveAll(portJSON)
+	}
+}
+
+func killByPort(port string) {
+	if !isPortOpen(port) {
+		return
+	}
+
+	portJSON := filepath.Join(util.HomeDir, ".config", "siyuan", "port.json")
+	os.RemoveAll(portJSON)
+
+	pid := pidByPort(port)
+	if "" == pid {
+		return
+	}
+
+	pidInt, _ := strconv.Atoi(pid)
+	proc, _ := goPS.FindProcess(pidInt)
+	var name string
+	if nil != proc {
+		name = proc.Executable()
+	}
+	kill(pid)
+	logging.LogInfof("killed process [name=%s, pid=%s]", name, pid)
+}
+
+func isPortOpen(port string) bool {
+	timeout := time.Second
+	conn, err := net.DialTimeout("tcp", net.JoinHostPort("127.0.0.1", port), timeout)
+	if nil != err {
+		return false
+	}
+	if nil != conn {
+		conn.Close()
+		return true
+	}
+	return false
+}
+
+func kill(pid string) {
+	var killCmd *exec.Cmd
+	if gulu.OS.IsWindows() {
+		killCmd = exec.Command("cmd", "/c", "TASKKILL /F /PID "+pid)
+	} else {
+		killCmd = exec.Command("kill", "-9", pid)
+	}
+	gulu.CmdAttr(killCmd)
+	killCmd.CombinedOutput()
+}
+
+func pidByPort(port string) (ret string) {
+	if gulu.OS.IsWindows() {
+		cmd := exec.Command("cmd", "/c", "netstat -ano | findstr "+port)
+		gulu.CmdAttr(cmd)
+		data, err := cmd.CombinedOutput()
+		if nil != err {
+			logging.LogErrorf("netstat failed: %s", err)
+			return
+		}
+		output := string(data)
+		lines := strings.Split(output, "\n")
+		for _, l := range lines {
+			if strings.Contains(l, "LISTENING") {
+				l = l[strings.Index(l, "LISTENING")+len("LISTENING"):]
+				l = strings.TrimSpace(l)
+				ret = l
+				return
+			}
+		}
+		return
+	}
+
+	cmd := exec.Command("lsof", "-Fp", "-i", ":"+port)
+	gulu.CmdAttr(cmd)
+	data, err := cmd.CombinedOutput()
+	if nil != err {
+		logging.LogErrorf("lsof failed: %s", err)
+		return
+	}
+	output := string(data)
+	lines := strings.Split(output, "\n")
+	for _, l := range lines {
+		if strings.HasPrefix(l, "p") {
+			l = l[1:]
+			ret = l
+			return
+		}
+	}
+	return
+}
diff --git a/kernel/server/serve.go b/kernel/server/serve.go
index eb88e50a6..941517f9f 100644
--- a/kernel/server/serve.go
+++ b/kernel/server/serve.go
@@ -24,10 +24,8 @@ import (
 	"net/http/pprof"
 	"net/url"
 	"os"
-	"os/exec"
 	"path"
 	"path/filepath"
-	"strconv"
 	"strings"
 	"time"
 
@@ -36,7 +34,6 @@ import (
 	"github.com/gin-contrib/sessions"
 	"github.com/gin-contrib/sessions/cookie"
 	"github.com/gin-gonic/gin"
-	goPS "github.com/mitchellh/go-ps"
 	"github.com/mssola/user_agent"
 	"github.com/olahol/melody"
 	"github.com/siyuan-note/logging"
@@ -458,124 +455,3 @@ func corsMiddleware() gin.HandlerFunc {
 		c.Next()
 	}
 }
-
-func killRunningKernel() {
-	defer logging.Recover()
-
-	if "dev" == util.Mode {
-		return
-	}
-
-	if util.ContainerStd != util.Container {
-		return
-	}
-
-	processes, err := goPS.Processes()
-	if nil != err {
-		logging.LogErrorf("get processes failed: %s", err)
-		killByPort(util.FixedPort)
-		return
-	}
-
-	killed := false
-	for _, process := range processes {
-		procName := strings.ToLower(process.Executable())
-		if strings.Contains(procName, "siyuan-kernel") {
-			kill(fmt.Sprintf("%d", process.Pid()))
-			killed = true
-		}
-	}
-
-	if killed {
-		portJSON := filepath.Join(util.HomeDir, ".config", "siyuan", "port.json")
-		os.RemoveAll(portJSON)
-	}
-}
-
-func killByPort(port string) {
-	if !isPortOpen(port) {
-		return
-	}
-
-	portJSON := filepath.Join(util.HomeDir, ".config", "siyuan", "port.json")
-	os.RemoveAll(portJSON)
-
-	pid := pidByPort(port)
-	if "" == pid {
-		return
-	}
-
-	pidInt, _ := strconv.Atoi(pid)
-	proc, _ := goPS.FindProcess(pidInt)
-	var name string
-	if nil != proc {
-		name = proc.Executable()
-	}
-	kill(pid)
-	logging.LogInfof("killed process [name=%s, pid=%s]", name, pid)
-}
-
-func isPortOpen(port string) bool {
-	timeout := time.Second
-	conn, err := net.DialTimeout("tcp", net.JoinHostPort("127.0.0.1", port), timeout)
-	if nil != err {
-		return false
-	}
-	if nil != conn {
-		conn.Close()
-		return true
-	}
-	return false
-}
-
-func kill(pid string) {
-	var killCmd *exec.Cmd
-	if gulu.OS.IsWindows() {
-		killCmd = exec.Command("cmd", "/c", "TASKKILL /F /PID "+pid)
-	} else {
-		killCmd = exec.Command("kill", "-9", pid)
-	}
-	gulu.CmdAttr(killCmd)
-	killCmd.CombinedOutput()
-}
-
-func pidByPort(port string) (ret string) {
-	if gulu.OS.IsWindows() {
-		cmd := exec.Command("cmd", "/c", "netstat -ano | findstr "+port)
-		gulu.CmdAttr(cmd)
-		data, err := cmd.CombinedOutput()
-		if nil != err {
-			logging.LogErrorf("netstat failed: %s", err)
-			return
-		}
-		output := string(data)
-		lines := strings.Split(output, "\n")
-		for _, l := range lines {
-			if strings.Contains(l, "LISTENING") {
-				l = l[strings.Index(l, "LISTENING")+len("LISTENING"):]
-				l = strings.TrimSpace(l)
-				ret = l
-				return
-			}
-		}
-		return
-	}
-
-	cmd := exec.Command("lsof", "-Fp", "-i", ":"+port)
-	gulu.CmdAttr(cmd)
-	data, err := cmd.CombinedOutput()
-	if nil != err {
-		logging.LogErrorf("lsof failed: %s", err)
-		return
-	}
-	output := string(data)
-	lines := strings.Split(output, "\n")
-	for _, l := range lines {
-		if strings.HasPrefix(l, "p") {
-			l = l[1:]
-			ret = l
-			return
-		}
-	}
-	return
-}