diff --git a/config.example.json b/config.example.json
index 6c6e05ee..7762cf83 100644
--- a/config.example.json
+++ b/config.example.json
@@ -30,8 +30,8 @@
     //threads_num:num of threads,1 by default
     "threads_num": 16,
     //enable_session:false by default
-    "enable_session": false,
-    "session_timeout": 0,
+    "enable_session": true,
+    "session_timeout": 1200,
     //document_root:Root path of HTTP document,defaut path is ./
     "document_root": "./",
     /* file_types:
diff --git a/lib/inc/drogon/CacheMap.h b/lib/inc/drogon/CacheMap.h
index afc09f53..e38edba9 100755
--- a/lib/inc/drogon/CacheMap.h
+++ b/lib/inc/drogon/CacheMap.h
@@ -84,26 +84,35 @@ class CacheMap
         {
             _wheels[i].resize(_bucketsNumPerWheel);
         }
-        _timerId = _loop->runEvery(_tickInterval, [=]() {
-            _ticksCounter++;
-            size_t t = _ticksCounter;
-            size_t pow = 1;
-            for (size_t i = 0; i < _wheelsNum; i++)
-            {
-                if ((t % pow) == 0)
+        if (_tickInterval > 0 &&
+            _wheelsNum > 0 &&
+            _bucketsNumPerWheel > 0)
+        {
+            _timerId = _loop->runEvery(_tickInterval, [=]() {
+                _ticksCounter++;
+                size_t t = _ticksCounter;
+                size_t pow = 1;
+                for (size_t i = 0; i < _wheelsNum; i++)
                 {
-                    CallbackBucket tmp;
+                    if ((t % pow) == 0)
                     {
-                        std::lock_guard<std::mutex> lock(bucketMutex_);
-                        //use tmp val to make this critical area as short as possible.
-                        _wheels[i].front().swap(tmp);
-                        _wheels[i].pop_front();
-                        _wheels[i].push_back(CallbackBucket());
+                        CallbackBucket tmp;
+                        {
+                            std::lock_guard<std::mutex> lock(bucketMutex_);
+                            //use tmp val to make this critical area as short as possible.
+                            _wheels[i].front().swap(tmp);
+                            _wheels[i].pop_front();
+                            _wheels[i].push_back(CallbackBucket());
+                        }
                     }
+                    pow = pow * _bucketsNumPerWheel;
                 }
-                pow = pow * _bucketsNumPerWheel;
-            }
-        });
+            });
+        }
+        else
+        {
+            _noWheels = true;
+        }
     };
     ~CacheMap()
     {
@@ -184,14 +193,14 @@ class CacheMap
         int timeout = 0;
 
         std::lock_guard<std::mutex> lock(mtx_);
-        if (_map.find(key) != _map.end())
+        auto iter = _map.find(key);
+        if (iter != _map.end())
         {
-            timeout = _map[key].timeout;
+            timeout = iter->second.timeout;
+            if (timeout > 0)
+                eraseAfter(timeout, key);
+            return iter->second.value;
         }
-
-        if (timeout > 0)
-            eraseAfter(timeout, key);
-
         return _map[key].value;
     }
     bool find(const T1 &key)
@@ -200,9 +209,10 @@ class CacheMap
         bool flag = false;
 
         std::lock_guard<std::mutex> lock(mtx_);
-        if (_map.find(key) != _map.end())
+        auto iter = _map.find(key);
+        if (iter != _map.end())
         {
-            timeout = _map[key].timeout;
+            timeout = iter->second.timeout;
             flag = true;
         }
 
@@ -235,6 +245,8 @@ class CacheMap
     size_t _wheelsNum;
     size_t _bucketsNumPerWheel;
 
+    bool _noWheels = false;
+
     void insertEntry(size_t delay, CallbackEntryPtr entryPtr)
     {
         //protected by bucketMutex;
@@ -270,6 +282,8 @@ class CacheMap
     }
     void eraseAfter(size_t delay, const T1 &key)
     {
+        if (_noWheels)
+            return;
         assert(_map.find(key) != _map.end());
 
         CallbackEntryPtr entryPtr;
diff --git a/lib/src/HttpAppFrameworkImpl.cc b/lib/src/HttpAppFrameworkImpl.cc
index e39c86cb..62b2ce13 100755
--- a/lib/src/HttpAppFrameworkImpl.cc
+++ b/lib/src/HttpAppFrameworkImpl.cc
@@ -473,7 +473,30 @@ void HttpAppFrameworkImpl::run()
     }
     if (_useSession)
     {
-        _sessionMapPtr = std::unique_ptr<CacheMap<std::string, SessionPtr>>(new CacheMap<std::string, SessionPtr>(&_loop));
+        if (_sessionTimeout > 0)
+        {
+            size_t wheelNum = 1;
+            size_t bucketNum = 0;
+            if (_sessionTimeout < 500)
+            {
+                bucketNum = _sessionTimeout + 1;
+            }
+            else
+            {
+                auto tmpTimeout = _sessionTimeout;
+                bucketNum = 100;
+                while (tmpTimeout > 100)
+                {
+                    wheelNum++;
+                    tmpTimeout = tmpTimeout / 100;
+                }
+            }
+            _sessionMapPtr = std::unique_ptr<CacheMap<std::string, SessionPtr>>(new CacheMap<std::string, SessionPtr>(&_loop, 1.0, wheelNum, bucketNum));
+        }
+        else if (_sessionTimeout == 0)
+        {
+            _sessionMapPtr = std::unique_ptr<CacheMap<std::string, SessionPtr>>(new CacheMap<std::string, SessionPtr>(&_loop, 0, 0, 0));
+        }
     }
     _responseCacheMap = std::unique_ptr<CacheMap<std::string, HttpResponsePtr>>(new CacheMap<std::string, HttpResponsePtr>(&_loop, 1.0, 4, 50)); //Max timeout up to about 70 days;
     _loop.loop();
diff --git a/tests/CacheMapTest2.cc b/tests/CacheMapTest2.cc
index 7fd0fa5f..e0319a5f 100755
--- a/tests/CacheMapTest2.cc
+++ b/tests/CacheMapTest2.cc
@@ -31,9 +31,12 @@ int main()
     });
     trantor::EventLoop mainLoop;
     mainLoop.runAt(now.after(3).roundSecond().after(0.0013), [&]() {
+        (*main_cachePtr)["new"]="new";
         if (main_cachePtr->find("1"))
         {
-            LOG_DEBUG << "find item 1";
+            LOG_DEBUG << "find item 1:" << (*main_cachePtr)["1"];
+            (*main_cachePtr)["1"] = "22";
+            LOG_DEBUG << (*main_cachePtr)["1"];
         }
         else
         {