diff --git a/f7/app.py b/f7/app.py
index b113d36..e8cf826 100644
--- a/f7/app.py
+++ b/f7/app.py
@@ -23,6 +23,7 @@ class _App:
         return cls._instance
 
     def __init__(self):
+        self._listened = False
         self._requestHandler = {}
         self._app = tornado.web.Application([
             (r"/webapp/index[\.]php", _mainHandler),
@@ -34,10 +35,14 @@ class _App:
         f7.udplog.setLogDirAndCreate(log_dir)
 
     def start(self):
-        tornado.ioloop.IOLoop.current().start()
+        if self._listened:
+            tornado.ioloop.IOLoop.current().start()
+        f7.timer.unInit()
+        f7.udplog.unInit()
 
     def listen(self, port):
         self._app.listen(port)
+        self._listened = True
 
     def callAt(self, when, callback):
         tornado.ioloop.IOLoop.current().call_at(when, callback)
diff --git a/f7/timer.py b/f7/timer.py
index b92697e..d776b8f 100644
--- a/f7/timer.py
+++ b/f7/timer.py
@@ -15,6 +15,9 @@ class _Timer:
     def __init__(self):
         pass
 
+    def unInit(self):
+        pass
+
     def callAt(self, when, callback):
         f7.app.callAt(when, callback)
 
diff --git a/f7/udplog.py b/f7/udplog.py
index 9a3a07f..3148e09 100644
--- a/f7/udplog.py
+++ b/f7/udplog.py
@@ -4,7 +4,6 @@ import os
 import time
 import datetime
 import traceback
-import _thread
 import threading
 
 import q7
@@ -28,19 +27,26 @@ class _UdpLog:
         self._topNode = None
         self._botNode = None
         self._workNode = None
+        self._terminated = False
+        self._cond = threading.Condition()
         self._msgLock = threading.Lock()
+        self._workerThread = threading.Thread(target = self._saveToFile, args = ())
 
     def init(self):
-        _thread.start_new_thread(self._saveToFile, ())
+        self._workerThread.start()
+
+    def unInit(self):
+        self._terminated = True
+        self._cond.acquire()
+        self._cond.notifyAll()
+        self._cond.release()
+        self._workerThread.join()
 
     def setLogDirAndCreate(self, logdir):
         if not os.path.exists(logdir):
             os.makedirs(logdir)
         self._logDir = logdir
 
-    def unInit(self):
-        pass
-
     def info(self, msg):
         self._addLog(str(datetime.datetime.now()) + '[INFO]' + str(msg))
 
@@ -71,28 +77,34 @@ class _UdpLog:
 
     def _saveToFile(self):
         try:
-            while True:
-                if not self._workNode and self._topNode:
-                    self._msgLock.acquire()
-                    try:
-                        self._workNode = self._topNode
-                        self._topNode = None
-                        self._botNode = None
-                    finally:
-                        self._msgLock.release()
-                if self._workNode:
-                    filename = datetime.datetime.now().strftime('log_' + str(os.getpid()) + '_%Y%m%d.log')
-                    try:
-                        with open(os.path.join(self._logDir, filename), 'a') as f:
-                            while self._workNode:
-                                nextNode = self._workNode.nextNode
-                                f.write(self._workNode.msg + '\r\n')
-                                self._workNode = nextNode
-                    except Exception as e:
-                        print(str(e), flush=True)
-                time.sleep(10)
+            while not self._terminated:
+                self._internalSave()
+                self._cond.acquire()
+                self._cond.wait(10)
+                self._cond.release()
+            self._internalSave()
         except:
             traceback.print_exec()
 
+    def _internalSave(self):
+        if not self._workNode and self._topNode:
+            self._msgLock.acquire()
+            try:
+                self._workNode = self._topNode
+                self._topNode = None
+                self._botNode = None
+            finally:
+                self._msgLock.release()
+        if self._workNode:
+            filename = datetime.datetime.now().strftime('log_' + str(os.getpid()) + '_%Y%m%d.log')
+            try:
+                with open(os.path.join(self._logDir, filename), 'a') as f:
+                    while self._workNode:
+                        nextNode = self._workNode.nextNode
+                        f.write(self._workNode.msg + '\r\n')
+                        self._workNode = nextNode
+            except Exception as e:
+                print(str(e), flush=True)
+
 def instance():
     return _UdpLog.instance()