diff --git a/README.md b/README.md
index 51e45ab..e759450 100644
--- a/README.md
+++ b/README.md
@@ -42,7 +42,7 @@ Atlas is a MySQL protocol-based database middleware project developed and mainta
 
 ### 5.Requirement and feedback
 
-If You have new functional requirements about Atlas in the production environment, or find a bug in the process of using Atlas. Welcome to send a mail to g-atlas@360.cn, we will reply as soon as possible. Also you can contact us in [Google group](https://groups.google.com/forum/#!forum/atlas-proxy). Enthusiastic user has established a QQ group:326544838, the developers of Atlas have also been in the QQ group.
+If You have new functional requirements about Atlas in the production environment, or find a bug in the process of using Atlas. Welcome to send a mail to g-atlas[at]360.cn, we will reply as soon as possible. Also you can contact us in [Google group](https://groups.google.com/forum/#!forum/atlas-proxy). Enthusiastic user has established a QQ group:326544838, the developers of Atlas have also been in the QQ group.
 
 ### 6.The origin of the name
 
diff --git a/README_ZH.md b/README_ZH.md
index 2eea989..73da456 100644
--- a/README_ZH.md
+++ b/README_ZH.md
@@ -1,7 +1,7 @@
 
 我们团队开发了另外一个有意思的项目 pika, pika 是一个兼容redis 协议的大容量的存储, 用来解决redis 内存不够的问题, 欢迎大家试试
 
-由于团队精力有限, 目前Atlas 依据满足了公司大部分的需求, 因此很多Issue 我们很难再继续满足. 但是我们欢迎社区里面喜欢Atlas, 愿意给Atlas 做贡献的小伙伴可以一起来改善Atlas, 给Atlas 提交代码. 欢迎联系 chenzongzhi@360.cn
+由于团队精力有限, 目前Atlas 依据满足了公司大部分的需求, 因此很多Issue 我们很难再继续满足. 但是我们欢迎社区里面喜欢Atlas, 愿意给Atlas 做贡献的小伙伴可以一起来改善Atlas, 给Atlas 提交代码. 欢迎联系 g-infra@360.cn!
 ### 一、简介
 
 
diff --git a/example.cnf b/example.cnf
new file mode 100644
index 0000000..8b7c2dd
--- /dev/null
+++ b/example.cnf
@@ -0,0 +1,22 @@
+[mysql-proxy]
+admin-username=admin
+admin-password=admin_password
+admin-lua-script=/usr/local/mysql-proxy/lib/mysql-proxy/lua/admin.lua
+log-level=message
+log-path=./log
+plugin-dir=./lib
+daemon=false
+keepalive=false
+event-threads=2
+instance=3470
+proxy-address=0.0.0.0:13470
+admin-address=0.0.0.0:23470
+proxy-backend-addresses=192.168.1.1:3306
+proxy-read-only-backend-addresses=192.168.1.2:3306
+client-ips=127.0.0.1,192.168.1,192.168.2.35
+lvs-ips=192.168.0.1
+pwds=user_name:user_password
+charset=utf8
+sql-log=ON
+max_conn_for_a_backend=0
+wait-timeout=60
diff --git a/plugins/proxy/proxy-plugin.c b/plugins/proxy/proxy-plugin.c
index c9b20ca..9e1cbfe 100644
--- a/plugins/proxy/proxy-plugin.c
+++ b/plugins/proxy/proxy-plugin.c
@@ -2103,6 +2103,16 @@ NETWORK_MYSQLD_PLUGIN_PROTO(proxy_disconnect_client) {
 		st->backend->connected_clients--;
 	}
 */
+
+    if (st && st->backend) {
+        if (!g_atomic_int_compare_and_exchange(&st->backend->connected_clients, 0, 0)) {
+            g_atomic_int_dec_and_test(&st->backend->connected_clients);
+        }
+        //g_critical("last in proxy_disconnect_client: %08x's connected_clients is %d\n", st->backend, st->backend->connected_clients);
+    }
+
+
+
 #ifdef HAVE_LUA_H
 	/* remove this cached script from registry */
 	if (st->L_ref > 0) {
diff --git a/src/chassis-mainloop.h b/src/chassis-mainloop.h
index b40b58d..195a462 100644
--- a/src/chassis-mainloop.h
+++ b/src/chassis-mainloop.h
@@ -69,6 +69,8 @@ struct chassis {
 	
 	chassis_stats_t *stats;			/**< the overall chassis stats, includes lua and glib allocation stats */
 
+    gint max_conn_for_a_backend;
+
 	/* network-io threads */
 	guint event_thread_count;
 
diff --git a/src/mysql-proxy-cli.c b/src/mysql-proxy-cli.c
index 56c2bdc..cce59ed 100644
--- a/src/mysql-proxy-cli.c
+++ b/src/mysql-proxy-cli.c
@@ -127,6 +127,8 @@ typedef struct {
 
 	gint max_files_number;
 
+    gint max_conn_for_a_backend;
+
 	gint event_thread_count;
 
 	gchar *log_level;
@@ -152,6 +154,7 @@ chassis_frontend_t *chassis_frontend_new(void) {
 	frontend->event_thread_count = 1;
 	frontend->max_files_number = 0;
 	frontend->wait_timeout = 0;
+    frontend->max_conn_for_a_backend = 0;
 
 	return frontend;
 }
@@ -201,7 +204,8 @@ int chassis_frontend_set_chassis_options(chassis_frontend_t *frontend, chassis_o
 	chassis_options_add(opts, "lua-cpath", 0, 0, G_OPTION_ARG_STRING, &(frontend->lua_cpath), "set the LUA_CPATH", "<...>");
 	chassis_options_add(opts, "instance", 0, 0, G_OPTION_ARG_STRING, &(frontend->instance_name), "instance name", "<name>");
 	chassis_options_add(opts, "wait-timeout", 0, 0, G_OPTION_ARG_INT, &(frontend->wait_timeout), "the number of seconds which Atlas waits for activity on a connection before closing it (default:0)", NULL);
-
+	chassis_options_add(opts, "max_conn_for_a_backend", 0, 0, G_OPTION_ARG_INT, &(frontend->max_conn_for_a_backend), "max conn for a backend(default: 0)", NULL);
+    
 	return 0;	
 }
 
@@ -349,6 +353,14 @@ int main_cmdline(int argc, char **argv) {
 	}
 	srv->wait_timeout = frontend->wait_timeout;
 
+	if (frontend->max_conn_for_a_backend <= 0) {
+		g_critical("--max_conn_for_a_backend is %d, which means there is not any conn limitation for a backend", frontend->max_conn_for_a_backend);
+	} else {
+		g_message("--max_conn_for_a_backend is %d ", frontend->max_conn_for_a_backend);
+    }
+
+    srv->max_conn_for_a_backend = frontend->max_conn_for_a_backend;
+
 	/* assign the mysqld part to the */
 	network_mysqld_init(srv, frontend->default_file); /* starts the also the lua-scope, LUA_PATH and LUA_CPATH have to be set before this being called */
 
diff --git a/src/network-backend.h b/src/network-backend.h
index 85ce855..d5ebde2 100644
--- a/src/network-backend.h
+++ b/src/network-backend.h
@@ -59,7 +59,7 @@ typedef struct {
 //	network_connection_pool *pool; /**< the pool of open connections */
 	GPtrArray *pools;
 
-	guint connected_clients; /**< number of open connections to this backend for SQF */
+	gint connected_clients; /**< number of open connections to this backend for SQF */
 
 	GString *uuid;           /**< the UUID of the backend */
 
diff --git a/src/network-conn-pool-lua.c b/src/network-conn-pool-lua.c
index dae6e29..ac56935 100644
--- a/src/network-conn-pool-lua.c
+++ b/src/network-conn-pool-lua.c
@@ -125,7 +125,12 @@ int network_connection_pool_lua_add_connection(network_mysqld_con *con) {
 		event_set(&(con->server->event), con->server->fd, EV_READ, network_mysqld_con_idle_handle, pool_entry);
 		chassis_event_add_local(con->srv, &(con->server->event)); /* add a event, but stay in the same thread */
 	}
-	
+
+    if (!g_atomic_int_compare_and_exchange(&st->backend->connected_clients, 0, 0)) {
+        g_atomic_int_dec_and_test(&st->backend->connected_clients);    
+        //g_critical("add_connection: %08x's connected_clients is %d\n", backend,  backend->connected_clients);
+    }
+
 //	st->backend->connected_clients--;
 	st->backend = NULL;
 	st->backend_ndx = -1;
@@ -136,7 +141,16 @@ int network_connection_pool_lua_add_connection(network_mysqld_con *con) {
 }
 
 network_socket *self_connect(network_mysqld_con *con, network_backend_t *backend, GHashTable *pwd_table) {
-	//1. connect DB
+
+    /*make sure that the max conn for the backend is no more than the config number
+     *when max_conn_for_a_backend is no more than 0, there is no limitation for max connection for a backend;
+     * */
+    if (con->srv->max_conn_for_a_backend > 0 && backend->connected_clients >= con->srv->max_conn_for_a_backend) {
+        g_critical("%s.%d: self_connect:%08x's connected_clients is %d, which are too many!",__FILE__, __LINE__, backend,  backend->connected_clients);
+        return NULL;
+    }
+    
+    //1. connect DB
 	network_socket *sock = network_socket_new();
 	network_address_copy(sock->dst, backend->addr);
 	if (-1 == (sock->fd = socket(sock->dst->addr.common.sa_family, sock->socket_type, 0))) {
@@ -267,7 +281,7 @@ network_socket *self_connect(network_mysqld_con *con, network_backend_t *backend
 
 	sock->challenge = challenge;
 	sock->response = network_mysqld_auth_response_copy(con->client->response);
-
+    g_atomic_int_inc(&backend->connected_clients);
 	return sock;
 }
 
@@ -304,11 +318,13 @@ network_socket *network_connection_pool_lua_swap(network_mysqld_con *con, int ba
 #ifdef DEBUG_CONN_POOL
 	g_debug("%s: (swap) check if we have a connection for this user in the pool '%s'", G_STRLOC, con->client->response ? con->client->response->username->str: "empty_user");
 #endif
+       int flag = 0;
 	network_connection_pool* pool = chassis_event_thread_pool(backend);
 	if (NULL == (send_sock = network_connection_pool_get(pool))) {
 		/**
 		 * no connections in the pool
 		 */
+        flag = 1;
 		if (NULL == (send_sock = self_connect(con, backend, pwd_table))) {
 			st->backend_ndx = -1;
 			return NULL;
@@ -325,6 +341,11 @@ network_socket *network_connection_pool_lua_swap(network_mysqld_con *con, int ba
 	st->backend = backend;
 //	st->backend->connected_clients++;
 	st->backend_ndx = backend_ndx;
+    
+        if (flag == 0 && !g_atomic_int_compare_and_exchange(&st->backend->connected_clients, 0, 0)) {
+            g_atomic_int_dec_and_test(&st->backend->connected_clients);
+            //g_critical("pool_lua_swap:%08x's connected_clients is %d\n", backend,  backend->connected_clients);
+        }
 
 	return send_sock;
 }
diff --git a/src/network-mysqld.c b/src/network-mysqld.c
index 82238ee..0d1ad6d 100644
--- a/src/network-mysqld.c
+++ b/src/network-mysqld.c
@@ -204,6 +204,14 @@ void network_mysqld_con_free(network_mysqld_con *con) {
 
 	if (con->server) network_socket_free(con->server);
 	if (con->client) network_socket_free(con->client);
+    
+    network_mysqld_con_lua_t *st = con->plugin_con_state;
+    if (st && st->backend) {
+        if (!g_atomic_int_compare_and_exchange(&st->backend->connected_clients, 0, 0)) {
+            g_atomic_int_dec_and_test(&st->backend->connected_clients);    
+            //g_critical("last in CON_STATE_CONNECT_SERVER: %08x's connected_clients is %d\n", st->onnected_clients);
+        }
+    }
 
 	/* we are still in the conns-array */
 /*
@@ -982,7 +990,10 @@ void network_mysqld_con_handle(int event_fd, short events, void *user_data) {
 				network_socket_free(con->server);
 				con->server = NULL;
 				ostate = CON_STATE_INIT;
-
+                if (!g_atomic_int_compare_and_exchange(&st->backend->connected_clients, 0, 0)) {
+                    g_atomic_int_dec_and_test(&st->backend->connected_clients);         
+                    //g_critical("last in CON_STATE_CONNECT_SERVER: %08x's connected_clients is %d\n", st->onnected_clients);
+                }
 				g_warning("timeout in connecting server");
 				break;
 			}
@@ -1120,6 +1131,10 @@ void network_mysqld_con_handle(int event_fd, short events, void *user_data) {
 			break;
 		case CON_STATE_READ_AUTH: {
 			/* read auth from client */
+            if (events == EV_TIMEOUT) {
+                con->state = CON_STATE_ERROR; 
+                break;
+            }
 			network_socket *recv_sock;
 
 			recv_sock = con->client;
@@ -1130,7 +1145,7 @@ void network_mysqld_con_handle(int event_fd, short events, void *user_data) {
 			case NETWORK_SOCKET_SUCCESS:
 				break;
 			case NETWORK_SOCKET_WAIT_FOR_EVENT:
-				WAIT_FOR_EVENT(con->client, EV_READ, 0);
+				WAIT_FOR_EVENT(con->client, EV_READ, srv->wait_timeout);
 				NETWORK_MYSQLD_CON_TRACK_TIME(con, "wait_for_event::read_auth");
 
 				return;