diff --git a/src/plugins/http/http_timer.c b/src/plugins/http/http_timer.c
index 42fe690..c8fc632 100644
--- a/src/plugins/http/http_timer.c
+++ b/src/plugins/http/http_timer.c
@@ -71,6 +71,8 @@
   http_tw_ctx_t *twc = &http_tw_ctx;
   vlib_node_t *n;
 
+  if (twc->tw.timers)
+    return;
   tw_timer_wheel_init_2t_1w_2048sl (&twc->tw, http_timer_process_expired_cb,
 				    1.0 /* timer interval */, ~0);
   clib_spinlock_init (&twc->tw_lock);
diff --git a/src/plugins/unittest/session_test.c b/src/plugins/unittest/session_test.c
index b7627ac..3364966 100644
--- a/src/plugins/unittest/session_test.c
+++ b/src/plugins/unittest/session_test.c
@@ -2073,6 +2073,63 @@
   return 0;
 }
 
+static f32
+session_get_memory_usage (void)
+{
+  clib_mem_heap_t *heap = clib_mem_get_per_cpu_heap ();
+  u8 *s = 0;
+  char *ss;
+  f32 used;
+
+  s = format (s, "%U\n", format_clib_mem_heap, heap, 0);
+  ss = strstr ((char *) s, "used:");
+  sscanf (ss, "used: %f", &used);
+  vec_free (s);
+  return (used);
+}
+
+static int
+session_test_enable_disable (vlib_main_t *vm, unformat_input_t *input)
+{
+  u32 iteration = 100, i;
+  uword was_enabled;
+  f32 was_using, now_using;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "repeat %d", &iteration))
+	;
+      else
+	{
+	  vlib_cli_output (vm, "parse error: '%U'", format_unformat_error,
+			   input);
+	  return -1;
+	}
+    }
+
+  was_enabled = clib_mem_trace_enable_disable (0);
+  /* warm up */
+  for (i = 0; i < 10; i++)
+    {
+      vnet_session_enable_disable (vm, 0);
+      vnet_session_enable_disable (vm, 1);
+    }
+  was_using = session_get_memory_usage ();
+
+  for (i = 0; i < iteration; i++)
+    {
+      vnet_session_enable_disable (vm, 0);
+      vnet_session_enable_disable (vm, 1);
+    }
+  now_using = session_get_memory_usage ();
+
+  clib_mem_trace_enable_disable (was_enabled);
+  SESSION_TEST ((was_using == now_using), "was using %.2fM, now using %.2fM",
+		was_using, now_using);
+
+  return 0;
+}
+
 static clib_error_t *
 session_test (vlib_main_t * vm,
 	      unformat_input_t * input, vlib_cli_command_t * cmd_arg)
@@ -2099,6 +2156,8 @@
 	res = session_test_mq_speed (vm, input);
       else if (unformat (input, "mq-basic"))
 	res = session_test_mq_basic (vm, input);
+      else if (unformat (input, "enable-disable"))
+	res = session_test_enable_disable (vm, input);
       else if (unformat (input, "all"))
 	{
 	  if ((res = session_test_basic (vm, input)))
@@ -2117,6 +2176,8 @@
 	    goto done;
 	  if ((res = session_test_mq_basic (vm, input)))
 	    goto done;
+	  if ((res = session_test_enable_disable (vm, input)))
+	    goto done;
 	}
       else
 	break;
diff --git a/src/vnet/session/application_local.c b/src/vnet/session/application_local.c
index 3cb743d..064dd6f 100644
--- a/src/vnet/session/application_local.c
+++ b/src/vnet/session/application_local.c
@@ -1350,13 +1350,21 @@
   ct_main_t *cm = &ct_main;
   ct_worker_t *wrk;
 
+  if (is_en == 0)
+    return 0;
+
   cm->n_workers = vlib_num_workers ();
   cm->fwrk_thread = transport_cl_thread ();
   vec_validate (cm->wrk, vtm->n_vlib_mains);
   vec_foreach (wrk, cm->wrk)
-    clib_spinlock_init (&wrk->pending_connects_lock);
-  clib_spinlock_init (&cm->ho_reuseable_lock);
-  clib_rwlock_init (&cm->app_segs_lock);
+    {
+      if (wrk->pending_connects_lock == 0)
+	clib_spinlock_init (&wrk->pending_connects_lock);
+    }
+  if (cm->ho_reuseable_lock == 0)
+    clib_spinlock_init (&cm->ho_reuseable_lock);
+  if (cm->app_segs_lock == 0)
+    clib_rwlock_init (&cm->app_segs_lock);
   vec_validate (cm->fwrk_pending_connects, cm->n_workers);
   return 0;
 }
diff --git a/src/vnet/tcp/tcp_timer.c b/src/vnet/tcp/tcp_timer.c
index d98d0d1..8ae3f22 100644
--- a/src/vnet/tcp/tcp_timer.c
+++ b/src/vnet/tcp/tcp_timer.c
@@ -20,6 +20,8 @@
 tcp_timer_initialize_wheel (tcp_timer_wheel_t * tw,
 			    void (*expired_timer_cb) (u32 *), f64 now)
 {
+  if (tw->timers)
+    return;
   tw_timer_wheel_init_tcp_twsl (tw, expired_timer_cb, TCP_TIMER_TICK, ~0);
   tw->last_run_time = now;
 }