diff --git a/src/chassis-event.c b/src/chassis-event.c
index d18b952..dd9b825 100644
--- a/src/chassis-event.c
+++ b/src/chassis-event.c
@@ -56,9 +56,7 @@ void
 chassis_event_add_with_timeout(chassis *chas, struct event *ev, struct timeval *tv)
 {
     event_base_set(chas->event_base, ev);
-#if NETWORK_DEBUG_TRACE_EVENT
     CHECK_PENDING_EVENT(ev);
-#endif
     event_add(ev, tv);
     g_debug("%s:event add ev:%p", G_STRLOC, ev);
 }
diff --git a/src/chassis-mainloop.c b/src/chassis-mainloop.c
index d45b64b..0154c6f 100644
--- a/src/chassis-mainloop.c
+++ b/src/chassis-mainloop.c
@@ -329,6 +329,7 @@ chassis_mainloop(void *_chas)
         }
     }
 
+#ifndef SIMPLE_PARSER
     chas->dist_tran_id = g_random_int_range(0, 100000000);
     int srv_id = g_random_int_range(0, 10000);
     if (chas->proxy_address) {
@@ -338,6 +339,7 @@ chassis_mainloop(void *_chas)
     }
     g_message("Initial dist_tran_id:%llu", chas->dist_tran_id);
     g_message("dist_tran_prefix:%s", chas->dist_tran_prefix);
+#endif
 
     /*
      * drop root privileges if requested
diff --git a/src/chassis-mainloop.h b/src/chassis-mainloop.h
index 2d4be32..be93cef 100644
--- a/src/chassis-mainloop.h
+++ b/src/chassis-mainloop.h
@@ -54,7 +54,9 @@ typedef struct chassis chassis;
 #define MAX_SERVER_NUM 64
 #define MAX_QUERY_TIME 1000
 #define MAX_WAIT_TIME 1024
+#define MAX_TRY_NUM 6
 #define MAX_DIST_TRAN_PREFIX 32
+#define DEFAULT_LIVE_TIME 7200
 
 #define MAX_ALLOWED_PACKET_CEIL    (1 * GB)
 #define MAX_ALLOWED_PACKET_DEFAULT (32 * MB)
diff --git a/src/chassis-options-utils.c b/src/chassis-options-utils.c
index 059f4a7..d46142b 100644
--- a/src/chassis-options-utils.c
+++ b/src/chassis-options-utils.c
@@ -532,7 +532,7 @@ show_max_alive_time(gpointer param) {
         return g_strdup_printf("%d (s)", srv->max_alive_time);
     }
     if(CAN_SAVE_OPTS_PROPERTY(opt_type)) {
-        if(srv->max_alive_time == 7200) {
+        if(srv->max_alive_time == DEFAULT_LIVE_TIME) {
             return NULL;
         }
         return g_strdup_printf("%d", srv->max_alive_time);
diff --git a/src/mysql-proxy-cli.c b/src/mysql-proxy-cli.c
index c9ca17a..84011a1 100644
--- a/src/mysql-proxy-cli.c
+++ b/src/mysql-proxy-cli.c
@@ -166,7 +166,7 @@ chassis_frontend_new(void)
 
     frontend->default_pool_size = 100;
     frontend->max_resp_len = 10 * 1024 * 1024;  /* 10M */
-    frontend->max_alive_time = 7200;
+    frontend->max_alive_time = DEFAULT_LIVE_TIME;
     frontend->merged_output_size = 8192;
     frontend->max_header_size = 65536;
     frontend->config_port = 3306;
diff --git a/src/network-backend.c b/src/network-backend.c
index 092fca6..512a5d2 100644
--- a/src/network-backend.c
+++ b/src/network-backend.c
@@ -31,7 +31,7 @@
 #include "cetus-users.h"
 
 const char *backend_state_t_str[] = {
-    "unkown",
+    "unknown",
     "online",
     "down",
     "maintaining",
@@ -39,7 +39,7 @@ const char *backend_state_t_str[] = {
 };
 
 const char *backend_type_t_str[] = {
-    "unkown",
+    "unknown",
     "read/write",
     "readonly"
 };
diff --git a/src/network-mysqld.c b/src/network-mysqld.c
index bf42df3..025bfc1 100644
--- a/src/network-mysqld.c
+++ b/src/network-mysqld.c
@@ -3304,6 +3304,7 @@ process_service_unavailable(network_mysqld_con *con)
         for (i = 0; i < con->servers->len; i++) {
             server_session_t *ss = g_ptr_array_index(con->servers, i);
             if (ss->fresh) {
+                CHECK_PENDING_EVENT(&(ss->server->event));
                 network_pool_add_idle_conn(ss->backend->pool, con->srv, ss->server);
                 ss->backend->connected_clients--;
                 g_message("%s: connected_clients sub:%d, %d ndx for con:%p", G_STRLOC,
@@ -4460,7 +4461,9 @@ chassis_event_add_with_timeout(srv, &(sock->event), timeout);
 static int
 process_self_event(server_connection_state_t *con, int events, int event_fd)
 {
+    g_debug("%s:events:%d, ev:%p, state:%d", G_STRLOC, events, (&con->server->event), con->state);
     if (events == EV_READ) {
+        g_debug("%s:EV_READ, ev:%p, state:%d", G_STRLOC, (&con->server->event), con->state);
         int b = -1;
         if (ioctl(con->server->fd, FIONREAD, &b)) {
             g_warning("ioctl(%d, FIONREAD, ...) failed: %s", event_fd, strerror(errno));
@@ -4477,7 +4480,7 @@ process_self_event(server_connection_state_t *con, int events, int event_fd)
             }
         }
     } else if (events == EV_TIMEOUT) {
-        g_debug("%s:timeout, ev:%p", G_STRLOC, (&con->server->event));
+        g_debug("%s:timeout, ev:%p, state:%d", G_STRLOC, (&con->server->event), con->state);
         if (con->state == ST_ASYNC_CONN) {
             g_message("%s: self conn timeout, state:%d, con:%p, server:%p", G_STRLOC, con->state, con, con->server);
             con->state = ST_ASYNC_ERROR;
@@ -4504,8 +4507,18 @@ process_self_server_read(server_connection_state_t *con)
     case NETWORK_SOCKET_SUCCESS:
         break;
     case NETWORK_SOCKET_WAIT_FOR_EVENT:{
+        con->retry_cnt++;
+        if (con->retry_cnt >= MAX_TRY_NUM) {
+            con->state = ST_ASYNC_ERROR;
+            break;
+        }
+        struct timeval timeout;
+        timeout.tv_sec = 3;
+        timeout.tv_usec = 0;
+        g_debug("%s: set timeout:%d for new conn:%p", G_STRLOC,
+                (int)timeout.tv_sec, con);
         /* call us again when you have a event */
-        ASYNC_WAIT_FOR_EVENT(con->server, EV_READ, NULL, con);
+        ASYNC_WAIT_FOR_EVENT(con->server, EV_READ, &timeout, con);
         return 0;
     }
     case NETWORK_SOCKET_ERROR:
@@ -4570,12 +4583,10 @@ process_self_read_auth_result(server_connection_state_t *con)
         network_mysqld_queue_reset(con->server);
         network_queue_clear(con->server->recv_queue);
         con->server->is_multi_stmt_set = con->is_multi_stmt_set;
-#if NETWORK_DEBUG_TRACE_EVENT
-        CHECK_PENDING_EVENT(&(con->server->event));
-#endif
         if (con->srv->is_back_compressed) {
             con->server->do_compress = 1;
         }
+        CHECK_PENDING_EVENT(&(con->server->event));
         network_pool_add_idle_conn(con->pool, con->srv, con->server);
         con->server = NULL;     /* tell _self_con_free we succeed */
         network_mysqld_self_con_free(con);
@@ -4639,10 +4650,18 @@ network_mysqld_self_con_handle(int event_fd, short events, void *user_data)
         case ST_ASYNC_READ_HANDSHAKE:
             g_assert(events == 0 || event_fd == con->server->fd);
 
+            g_debug("%s: ST_ASYNC_READ_HANDSHAKE for con:%p, connection %s and %s",
+                G_STRLOC, con, con->server->src->name->str, con->server->dst->name->str);
+
+
             if (!process_self_server_read(con)) {
                 return;
             }
 
+            if (con->state == ST_ASYNC_ERROR) {
+                break;
+            }
+
             switch (proxy_self_read_handshake(srv, con)) {
             case RET_SUCCESS:
                 break;
@@ -4882,6 +4901,8 @@ network_connection_pool_create_conns(chassis *srv)
                           G_STRLOC, i, scs->server, scs);
 
                 scs->backend->connected_clients++;
+                int create_err = 0;
+
                 switch (network_socket_connect(scs->server)) {
                 case NETWORK_SOCKET_ERROR_RETRY:{
                     scs->state = ST_ASYNC_CONN;
@@ -4900,6 +4921,7 @@ network_connection_pool_create_conns(chassis *srv)
                     g_message("%s: set backend conn:%p read handshake", G_STRLOC, scs);
                     break;
                 default:
+                    create_err = 1;
                     scs->backend->connected_clients--;
                     network_mysqld_self_con_free(scs);
                     if (scs->srv->disable_threads) {
@@ -4913,6 +4935,10 @@ network_connection_pool_create_conns(chassis *srv)
                     }
                     break;
                 }
+
+                if (create_err) {
+                    break;
+                }
             }
         }
     }
diff --git a/src/network-mysqld.h b/src/network-mysqld.h
index 60afd14..7ea8698 100644
--- a/src/network-mysqld.h
+++ b/src/network-mysqld.h
@@ -340,6 +340,7 @@ struct server_connection_state_t {
     chassis *srv;
     network_connection_pool *pool;
     unsigned int is_multi_stmt_set:1;
+    unsigned int retry_cnt:4;
     guint8 charset_code;
 };
 
diff --git a/src/plugin-common.c b/src/plugin-common.c
index 9fc7f5c..9a1cc7a 100644
--- a/src/plugin-common.c
+++ b/src/plugin-common.c
@@ -584,6 +584,7 @@ proxy_put_shard_conn_to_pool(network_mysqld_con *con)
 
             int alive_time = con->srv->current_time - server->create_time;
             if (alive_time > con->srv->max_alive_time) {
+                g_debug("%s: reach max_alive_time", G_STRLOC);
                 is_put_to_pool_allowed = 0;
             }