vcl/session: apps with process workers

Allow apps to register child processes as app workers. In particular,
on fork vcl now registers the child process with vpp as a new worker.

Change-Id: I52a65fbc3292962b1f6e1fe0f6153f739e6e0d4a
Signed-off-by: Florin Coras <fcoras@cisco.com>

13 files changed, 236 insertions, 72 deletions

diff --git a/src/plugins/unittest/session_test.c b/src/plugins/unittest/session_test.c
index 182a8e806ea..e24516668ff 100644
--- a/src/plugins/unittest/session_test.c
+++ b/src/plugins/unittest/session_test.c
@@ -216,6 +216,7 @@ session_test_basic (vlib_main_t * vm, unformat_input_t * input)
 
   vnet_app_detach_args_t detach_args = {
     .app_index = server_index,
+    .api_client_index = ~0,
   };
   vnet_application_detach (&detach_args);
   return 0;
@@ -393,6 +394,7 @@ session_test_endpoint_cfg (vlib_main_t * vm, unformat_input_t * input)
 
   vnet_app_detach_args_t detach_args = {
     .app_index = server_index,
+    .api_client_index = ~0,
   };
   vnet_application_detach (&detach_args);
   detach_args.app_index = client_index;
@@ -463,6 +465,7 @@ session_test_namespace (vlib_main_t * vm, unformat_input_t * input)
 
   vnet_app_detach_args_t detach_args = {
     .app_index = 0,
+    .api_client_index = ~0,
   };
 
   ip4_address_t intf_addr = {
@@ -1562,6 +1565,7 @@ session_test_rules (vlib_main_t * vm, unformat_input_t * input)
   vec_free (args.table_args.tag);
   vnet_app_detach_args_t detach_args = {
     .app_index = server_index,
+    .api_client_index = ~0,
   };
   vnet_application_detach (&detach_args);
 
@@ -1677,6 +1681,7 @@ session_test_proxy (vlib_main_t * vm, unformat_input_t * input)
 
   vnet_app_detach_args_t detach_args = {
     .app_index = server_index,
+    .api_client_index = ~0,
   };
   vnet_application_detach (&detach_args);
 
diff --git a/src/vcl/vcl_bapi.c b/src/vcl/vcl_bapi.c
index ea8f2ce5651..7dd601cf737 100644
--- a/src/vcl/vcl_bapi.c
+++ b/src/vcl/vcl_bapi.c
@@ -148,17 +148,13 @@ vl_api_app_worker_add_del_reply_t_handler (vl_api_app_worker_add_del_reply_t *
 		    format_api_error, ntohl (mp->retval));
       goto failed;
     }
-  wrk_index = clib_net_to_host_u32 (mp->wrk_index);
-  if (mp->context != wrk_index)
-    {
-      clib_warning ("VCL<%d>: wrk numbering doesn't match ours: %u, vpp: %u",
-		    getpid (), mp->context, wrk_index);
-      goto failed;
-    }
+  wrk_index = mp->context;
+  wrk = vcl_worker_get (wrk_index);
+  wrk->vpp_wrk_index = clib_net_to_host_u32 (mp->wrk_index);
+
   if (!mp->is_add)
     return;
 
-  wrk = vcl_worker_get (wrk_index);
   wrk->app_event_queue = uword_to_pointer (mp->app_event_queue_address,
 					   svm_msg_q_t *);
 
@@ -193,6 +189,7 @@ vl_api_app_worker_add_del_reply_t_handler (vl_api_app_worker_add_del_reply_t *
 	goto failed;
     }
   vcm->app_state = STATE_APP_READY;
+  VDBG (0, "worker %u vpp-worker %u added", wrk_index, wrk->vpp_wrk_index);
   return;
 
 failed:
@@ -432,7 +429,7 @@ vcl_send_app_worker_add_del (u8 is_add)
 
   mp->_vl_msg_id = ntohs (VL_API_APP_WORKER_ADD_DEL);
   mp->client_index = vcm->my_client_index;
-  mp->app_api_index = clib_host_to_net_u32 (vcm->my_client_index);
+  mp->app_api_index = clib_host_to_net_u32 (vcm->main_api_client_index);
   mp->context = wrk_index;
   mp->is_add = is_add;
   if (!is_add)
@@ -444,6 +441,7 @@ vcl_send_app_worker_add_del (u8 is_add)
 void
 vppcom_send_connect_sock (vcl_session_t * session)
 {
+  vcl_worker_t *wrk = vcl_worker_get_current ();
   vl_api_connect_sock_t *cmp;
 
   cmp = vl_msg_api_alloc (sizeof (*cmp));
@@ -451,7 +449,7 @@ vppcom_send_connect_sock (vcl_session_t * session)
   cmp->_vl_msg_id = ntohs (VL_API_CONNECT_SOCK);
   cmp->client_index = vcm->my_client_index;
   cmp->context = session->session_index;
-  cmp->wrk_index = vcl_get_worker_index ();
+  cmp->wrk_index = wrk->vpp_wrk_index;
   cmp->is_ip4 = session->transport.is_ip4;
   clib_memcpy_fast (cmp->ip, &session->transport.rmt_ip, sizeof (cmp->ip));
   cmp->port = session->transport.rmt_port;
@@ -479,6 +477,7 @@ vppcom_send_disconnect_session (u64 vpp_handle)
 void
 vppcom_send_bind_sock (vcl_session_t * session)
 {
+  vcl_worker_t *wrk = vcl_worker_get_current ();
   vl_api_bind_sock_t *bmp;
 
   /* Assumes caller has acquired spinlock: vcm->sessions_lockp */
@@ -488,7 +487,7 @@ vppcom_send_bind_sock (vcl_session_t * session)
   bmp->_vl_msg_id = ntohs (VL_API_BIND_SOCK);
   bmp->client_index = vcm->my_client_index;
   bmp->context = session->session_index;
-  bmp->wrk_index = vcl_get_worker_index ();
+  bmp->wrk_index = wrk->vpp_wrk_index;
   bmp->is_ip4 = session->transport.is_ip4;
   clib_memcpy_fast (bmp->ip, &session->transport.lcl_ip, sizeof (bmp->ip));
   bmp->port = session->transport.lcl_port;
@@ -500,6 +499,7 @@ vppcom_send_bind_sock (vcl_session_t * session)
 void
 vppcom_send_unbind_sock (u64 vpp_handle)
 {
+  vcl_worker_t *wrk = vcl_worker_get_current ();
   vl_api_unbind_sock_t *ump;
 
   ump = vl_msg_api_alloc (sizeof (*ump));
@@ -507,7 +507,7 @@ vppcom_send_unbind_sock (u64 vpp_handle)
 
   ump->_vl_msg_id = ntohs (VL_API_UNBIND_SOCK);
   ump->client_index = vcm->my_client_index;
-  ump->wrk_index = vcl_get_worker_index ();
+  ump->wrk_index = wrk->vpp_wrk_index;
   ump->handle = vpp_handle;
   vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & ump);
 }
@@ -556,15 +556,13 @@ vppcom_connect_to_vpp (char *app_name)
       if (vl_socket_client_connect ((char *) vcl_cfg->vpp_api_socket_name,
 				    app_name, 0 /* default rx/tx buffer */ ))
 	{
-	  clib_warning ("VCL<%d>: app (%s) socket connect failed!",
-			getpid (), app_name);
+	  VERR ("app (%s) socket connect failed!", app_name);
 	  return VPPCOM_ECONNREFUSED;
 	}
 
       if (vl_socket_client_init_shm (0))
 	{
-	  clib_warning ("VCL<%d>: app (%s) init shm failed!",
-			getpid (), app_name);
+	  VERR ("app (%s) init shm failed!", app_name);
 	  return VPPCOM_ECONNREFUSED;
 	}
     }
@@ -573,14 +571,13 @@ vppcom_connect_to_vpp (char *app_name)
       if (!vcl_cfg->vpp_api_filename)
 	vcl_cfg->vpp_api_filename = format (0, "/vpe-api%c", 0);
 
-      VDBG (0, "VCL<%d>: app (%s) connecting to VPP api (%s)...", getpid (),
+      VDBG (0, "app (%s) connecting to VPP api (%s)...",
 	    app_name, vcl_cfg->vpp_api_filename);
 
       if (vl_client_connect_to_vlib ((char *) vcl_cfg->vpp_api_filename,
 				     app_name, vcm->cfg.vpp_api_q_length) < 0)
 	{
-	  clib_warning ("VCL<%d>: app (%s) connect failed!", getpid (),
-			app_name);
+	  VERR ("app (%s) connect failed!", app_name);
 	  return VPPCOM_ECONNREFUSED;
 	}
 
@@ -590,8 +587,7 @@ vppcom_connect_to_vpp (char *app_name)
   vcm->my_client_index = (u32) am->my_client_index;
   vcm->app_state = STATE_APP_CONN_VPP;
 
-  VDBG (0, "VCL<%d>: app (%s) is connected to VPP!", getpid (), app_name);
-
+  VDBG (0, "app (%s) is connected to VPP!", app_name);
   vcl_evt (VCL_EVT_INIT, vcm);
   return VPPCOM_OK;
 }
diff --git a/src/vcl/vcl_cfg.c b/src/vcl/vcl_cfg.c
index e39e5177908..3e92941d720 100644
--- a/src/vcl/vcl_cfg.c
+++ b/src/vcl/vcl_cfg.c
@@ -22,6 +22,7 @@
 static vppcom_main_t _vppcom_main = {
   .debug = VPPCOM_DEBUG_INIT,
   .is_init = 0,
+  .main_api_client_index = ~0,
   .my_client_index = ~0
 };
 
@@ -170,6 +171,7 @@ vppcom_cfg_heapsize (char *conf_fname)
 	      goto defaulted;
 	    }
 	}
+      free (argv[i]);
     }
 
 defaulted:
@@ -231,8 +233,7 @@ vppcom_cfg_read_file (char *conf_fname)
 
   if (fstat (fd, &s) < 0)
     {
-      VCFG_DBG (0,
-		"VCL<%d>: failed to stat `%s', using default configuration",
+      VCFG_DBG (0, "VCL<%d>: failed to stat `%s' using default configuration",
 		getpid (), conf_fname);
       goto file_done;
     }
@@ -254,17 +255,21 @@ vppcom_cfg_read_file (char *conf_fname)
       if (unformat (line_input, "vcl {"))
 	{
 	  vc_cfg_input = 1;
+	  unformat_free (line_input);
 	  continue;
 	}
 
       if (vc_cfg_input)
 	{
-	  if (unformat (line_input, "heapsize %lu", &vcl_cfg->heapsize))
+	  if (unformat (line_input, "heapsize %U", unformat_memory_size,
+			&vcl_cfg->heapsize))
 	    {
 	      VCFG_DBG (0, "VCL<%d>: configured heapsize %lu", getpid (),
 			vcl_cfg->heapsize);
 	    }
-	  if (unformat (line_input, "max-workers %u", &vcl_cfg->max_workers))
+	  else
+	    if (unformat
+		(line_input, "max-workers %u", &vcl_cfg->max_workers))
 	    {
 	      VCFG_DBG (0, "VCL<%d>: configured max-workers %u", getpid (),
 			vcl_cfg->max_workers);
@@ -490,6 +495,7 @@ vppcom_cfg_read_file (char *conf_fname)
 	      vc_cfg_input = 0;
 	      VCFG_DBG (0, "VCL<%d>: completed parsing vppcom config!",
 			getpid ());
+	      unformat_free (line_input);
 	      goto input_done;
 	    }
 	  else
@@ -501,6 +507,7 @@ vppcom_cfg_read_file (char *conf_fname)
 				&line_input->buffer[line_input->index]);
 		}
 	    }
+	  unformat_free (line_input);
 	}
     }
 
diff --git a/src/vcl/vcl_debug.h b/src/vcl/vcl_debug.h
index 7b284166503..48ff21af1de 100644
--- a/src/vcl/vcl_debug.h
+++ b/src/vcl/vcl_debug.h
@@ -23,7 +23,16 @@
 
 #define VDBG(_lvl, _fmt, _args...) 					\
   if (VCL_DBG_ON && vcm->debug > _lvl)					\
-    clib_warning ("vcl<w%d>: " _fmt, __vcl_worker_index, ##_args)
+    clib_warning ("vcl<%d:%d>: " _fmt, vcm->current_pid, 		\
+		  __vcl_worker_index, ##_args)
+
+#define VWRN(_fmt, _args...)						\
+clib_warning ("vcl<%d:%d>: " _fmt, vcm->current_pid, 			\
+		__vcl_worker_index, ##_args)
+
+#define VERR(_fmt, _args...)						\
+  clib_warning ("vcl<%d:%d>: ERROR " _fmt, vcm->current_pid, 		\
+		__vcl_worker_index, ##_args)
 
 #define foreach_vcl_dbg_evt						\
   _(INIT, "vcl init track")						\
diff --git a/src/vcl/vcl_private.h b/src/vcl/vcl_private.h
index d1a40b933a7..7bb0dbc5a66 100644
--- a/src/vcl/vcl_private.h
+++ b/src/vcl/vcl_private.h
@@ -219,8 +219,12 @@ typedef struct vcl_worker_
   /* Session pool */
   vcl_session_t *sessions;
 
+  /** Worker/thread index in current process */
   u32 wrk_index;
 
+  /** Worker index in vpp*/
+  u32 vpp_wrk_index;
+
   /** Message queues epoll fd. Initialized only if using mqs with eventfds */
   int mqs_epfd;
 
@@ -272,15 +276,26 @@ typedef struct vppcom_main_t_
   u32 debug;
   pthread_t main_cpu;
 
-  /** VPP binary api input queue */
-  svm_queue_t *vl_input_queue;
+  /** Main process pid */
+  pid_t main_pid;
+
+  /** Current pid, may be different from main_pid if forked child */
+  pid_t current_pid;
+
+  /** Main process api client index. It's used by vpp to identify the app */
+  u32 main_api_client_index;
 
   /** API client handle */
   u32 my_client_index;
 
+  /** VPP binary api input queue */
+  svm_queue_t *vl_input_queue;
+
   /** State of the connection, shared between msg RX thread and main thread */
   volatile app_state_t app_state;
 
+  u8 *app_name;
+
   /** VCL configuration */
   vppcom_cfg_t cfg;
 
diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index 99547377523..669f04fe1e3 100644
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -688,6 +688,52 @@ vppcom_session_disconnect (u32 session_handle)
   return VPPCOM_OK;
 }
 
+static void
+vcl_cleanup_bapi (void)
+{
+  api_main_t *am = &api_main;
+
+  am->my_client_index = ~0;
+  am->my_registration = 0;
+  am->vl_input_queue = 0;
+  am->msg_index_by_name_and_crc = 0;
+
+  vl_client_api_unmap ();
+}
+
+void
+vcl_app_fork_child_handler (void)
+{
+  u8 *child_name;
+  int rv;
+
+  vcm->current_pid = getpid ();
+  vcl_set_worker_index (0);
+
+  VDBG (0, "initializing forked child");
+  child_name = format (0, "%v-child-%u%c", vcm->app_name, getpid (), 0);
+
+  vcl_cleanup_bapi ();
+  vppcom_api_hookup ();
+  vcm->app_state = STATE_APP_START;
+  rv = vppcom_connect_to_vpp ((char *) child_name);
+  vec_free (child_name);
+  if (rv)
+    {
+      VERR ("couldn't connect to VPP!");
+      return;
+    }
+
+  vcm->app_state = STATE_APP_ADDING_WORKER;
+  vcl_send_app_worker_add_del (1 /* is_add */ );
+  if (vcl_wait_for_app_state_change (STATE_APP_READY))
+    {
+      VERR ("failed to add worker to vpp");
+      return;
+    }
+  VDBG (0, "forked child main worker initialized");
+}
+
 /*
  * VPPCOM Public API functions
  */
@@ -704,12 +750,15 @@ vppcom_app_create (char *app_name)
       vcl_cfg = &vcm->cfg;
 
       vcm->main_cpu = pthread_self ();
+      vcm->main_pid = vcm->current_pid = getpid ();
+      vcm->app_name = format (0, "%s", app_name);
       vppcom_init_error_string_table ();
       svm_fifo_segment_main_init (vcl_cfg->segment_baseva,
 				  20 /* timeout in secs */ );
       pool_init_fixed (vcm->workers, vcl_cfg->max_workers);
       clib_spinlock_init (&vcm->workers_lock);
       vcl_worker_alloc_and_init ();
+      pthread_atfork (NULL, NULL, vcl_app_fork_child_handler);
     }
 
   if (vcm->my_client_index == ~0)
@@ -721,31 +770,28 @@ vppcom_app_create (char *app_name)
       rv = vppcom_connect_to_vpp (app_name);
       if (rv)
 	{
-	  clib_warning ("VCL<%d>: ERROR: couldn't connect to VPP!",
-			getpid ());
+	  VERR ("couldn't connect to VPP!");
 	  return rv;
 	}
-
-      VDBG (0, "VCL<%d>: sending session enable", getpid ());
+      vcm->main_api_client_index = vcm->my_client_index;
+      VDBG (0, "sending session enable");
       rv = vppcom_app_session_enable ();
       if (rv)
 	{
-	  clib_warning ("VCL<%d>: ERROR: vppcom_app_session_enable() "
-			"failed!", getpid ());
+	  VERR ("vppcom_app_session_enable() failed!");
 	  return rv;
 	}
 
-      VDBG (0, "VCL<%d>: sending app attach", getpid ());
+      VDBG (0, "sending app attach");
       rv = vppcom_app_attach ();
       if (rv)
 	{
-	  clib_warning ("VCL<%d>: ERROR: vppcom_app_attach() failed!",
-			getpid ());
+	  VERR ("vppcom_app_attach() failed!");
 	  return rv;
 	}
 
-      VDBG (0, "VCL<%d>: app_name '%s', my_client_index %d (0x%x)",
-	    getpid (), app_name, vcm->my_client_index, vcm->my_client_index);
+      VDBG (0, "app_name '%s', my_client_index %d (0x%x)",
+	    app_name, vcm->my_client_index, vcm->my_client_index);
     }
 
   return VPPCOM_OK;
@@ -760,8 +806,8 @@ vppcom_app_destroy (void)
   if (vcm->my_client_index == ~0)
     return;
 
-  VDBG (0, "VCL<%d>: detaching from VPP, my_client_index %d (0x%x)",
-	getpid (), vcm->my_client_index, vcm->my_client_index);
+  VDBG (0, "detaching from VPP, my_client_index %d (0x%x)",
+	vcm->my_client_index, vcm->my_client_index);
   vcl_evt (VCL_EVT_DETACH, vcm);
 
   vppcom_app_send_detach ();
@@ -770,11 +816,12 @@ vppcom_app_destroy (void)
   rv = vcl_wait_for_app_state_change (STATE_APP_ENABLED);
   vcm->cfg.app_timeout = orig_app_timeout;
   if (PREDICT_FALSE (rv))
-    VDBG (0, "VCL<%d>: application detach timed out! returning %d (%s)",
-	  getpid (), rv, vppcom_retval_str (rv));
+    VDBG (0, "application detach timed out! returning %d (%s)",
+	  rv, vppcom_retval_str (rv));
 
   vcl_elog_stop (vcm);
   vl_client_disconnect_from_vlib ();
+  vec_free (vcm->app_name);
   vcm->my_client_index = ~0;
   vcm->app_state = STATE_APP_START;
 }
@@ -798,7 +845,7 @@ vppcom_session_create (u8 proto, u8 is_nonblocking)
   vcl_evt (VCL_EVT_CREATE, session, session_type, session->session_state,
 	   is_nonblocking, session_index);
 
-  VDBG (0, "VCL<%d>: sid %u", getpid (), session->session_index);
+  VDBG (0, "created sid %u", session->session_index);
 
   return vcl_session_handle (session);
 }
diff --git a/src/vnet/session/application.c b/src/vnet/session/application.c
index 1d7b3ad1125..72c57688e42 100644
--- a/src/vnet/session/application.c
+++ b/src/vnet/session/application.c
@@ -112,11 +112,11 @@ app_get_name_from_reg_index (application_t * app)
   return app_name;
 }
 
-static u8 *
+static const u8 *
 app_get_name (application_t * app)
 {
   if (!app->name)
-    return app_get_name_from_reg_index (app);
+    app->name = app_get_name_from_reg_index (app);
   return app->name;
 }
 
@@ -174,18 +174,27 @@ application_api_queue_is_full (application_t * app)
 }
 
 /**
- * Returns app name
- *
- * Since the name is not stored per app, we generate it on the fly. It is
- * the caller's responsibility to free the vector
+ * Returns app name for app-index
  */
-u8 *
+const u8 *
 application_name_from_index (u32 app_index)
 {
   application_t *app = application_get (app_index);
   if (!app)
     return 0;
-  return app_get_name_from_reg_index (app);
+  return app_get_name (app);
+}
+
+static void
+application_api_table_add (u32 app_index, u32 api_client_index)
+{
+  hash_set (app_main.app_by_api_client_index, api_client_index, app_index);
+}
+
+static void
+application_api_table_del (u32 api_client_index)
+{
+  hash_unset (app_main.app_by_api_client_index, api_client_index);
 }
 
 static void
@@ -213,7 +222,7 @@ application_lookup (u32 api_client_index)
   uword *p;
   p = hash_get (app_main.app_by_api_client_index, api_client_index);
   if (p)
-    return application_get (p[0]);
+    return application_get_if_valid (p[0]);
 
   return 0;
 }
@@ -440,6 +449,50 @@ application_free (application_t * app)
   pool_put (app_main.app_pool, app);
 }
 
+void
+application_detach_process (application_t * app, u32 api_client_index)
+{
+  vnet_app_worker_add_del_args_t _args = { 0 }, *args = &_args;
+  app_worker_map_t *wrk_map;
+  u32 *wrks = 0, *wrk_index;
+  app_worker_t *app_wrk;
+
+  if (api_client_index == ~0)
+    {
+      application_free (app);
+      return;
+    }
+
+  APP_DBG ("Detaching for app %v index %u api client index %u", app->name,
+	   app->app_index, app->api_client_index);
+
+  /* *INDENT-OFF* */
+  pool_foreach (wrk_map, app->worker_maps, ({
+    app_wrk = app_worker_get (wrk_map->wrk_index);
+    if (app_wrk->api_index == api_client_index)
+      vec_add1 (wrks, app_wrk->wrk_index);
+  }));
+  /* *INDENT-ON* */
+
+  if (!vec_len (wrks))
+    {
+      clib_warning ("no workers for app %u api_index %u", app->app_index,
+		    api_client_index);
+      return;
+    }
+
+  args->app_index = app->app_index;
+  args->api_index = api_client_index;
+  vec_foreach (wrk_index, wrks)
+  {
+    app_wrk = app_worker_get (wrk_index[0]);
+    args->wrk_index = app_wrk->wrk_map_index;
+    args->is_add = 0;
+    vnet_app_worker_add_del (args);
+  }
+  vec_free (wrks);
+}
+
 app_worker_t *
 application_get_worker (application_t * app, u32 wrk_map_index)
 {
@@ -456,6 +509,12 @@ application_get_default_worker (application_t * app)
   return application_get_worker (app, 0);
 }
 
+u32
+application_n_workers (application_t * app)
+{
+  return pool_elts (app->worker_maps);
+}
+
 app_worker_t *
 application_listener_select_worker (stream_session_t * ls, u8 is_local)
 {
@@ -609,6 +668,7 @@ app_worker_alloc_and_init (application_t * app, app_worker_t ** wrk)
   app_wrk->listeners_table = hash_create (0, sizeof (u64));
   app_wrk->event_queue = segment_manager_event_queue (sm);
   app_wrk->app_is_builtin = application_is_builtin (app);
+  app_wrk->api_index = app->api_client_index;
 
   /*
    * Segment manager for local sessions
@@ -815,7 +875,8 @@ application_stop_listen (u32 app_index, u32 app_wrk_index,
   app_listener = app_listener_get (app, listener->listener_db_index);
   if (!clib_bitmap_get (app_listener->workers, app_wrk_index))
     {
-      clib_warning ("worker not listening on handle %lu", handle);
+      clib_warning ("worker %u not listening on handle %lu", app_wrk_index,
+		    handle);
       return 0;
     }
 
@@ -899,6 +960,15 @@ vnet_app_worker_add_del (vnet_app_worker_add_del_args_t * a)
     {
       if ((rv = app_worker_alloc_and_init (app, &app_wrk)))
 	return clib_error_return_code (0, rv, 0, "app wrk init: %d", rv);
+
+      /* Map worker api index to the app */
+      if (a->api_index != app->api_client_index
+	  && app->api_client_index != APP_INVALID_INDEX)
+	{
+	  app_wrk->api_index = a->api_index;
+	  application_api_table_add (app->app_index, a->api_index);
+	}
+
       sm = segment_manager_get (app_wrk->first_segment_manager);
       fs = segment_manager_get_segment_w_lock (sm, 0);
       a->segment = &fs->ssvm;
@@ -914,11 +984,15 @@ vnet_app_worker_add_del (vnet_app_worker_add_del_args_t * a)
 				       "App %u does not have worker %u",
 				       app->app_index, a->wrk_index);
       app_wrk = app_worker_get (wrk_map->wrk_index);
-      app_worker_map_free (app, wrk_map);
       if (!app_wrk)
 	return clib_error_return_code (0, VNET_API_ERROR_INVALID_VALUE, 0,
 				       "No worker %u", a->wrk_index);
+      if (app->api_client_index != app_wrk->api_index)
+	application_api_table_del (app_wrk->api_index);
       app_worker_free (app_wrk);
+      app_worker_map_free (app, wrk_map);
+      if (application_n_workers (app) == 0)
+	application_free (app);
     }
   return 0;
 }
@@ -1916,7 +1990,8 @@ format_app_worker_listener (u8 * s, va_list * args)
   int verbose = va_arg (*args, int);
   stream_session_t *listener;
   application_t *app;
-  u8 *app_name, *str;
+  const u8 *app_name;
+  u8 *str;
 
   if (!app_wrk)
     {
@@ -1930,7 +2005,7 @@ format_app_worker_listener (u8 * s, va_list * args)
     }
 
   app = application_get (app_wrk->app_index);
-  app_name = app_get_name_from_reg_index (app);
+  app_name = app_get_name (app);
   listener = listen_session_get_from_handle (handle);
   str = format (0, "%U", format_stream_session, listener, verbose);
 
@@ -1944,7 +2019,6 @@ format_app_worker_listener (u8 * s, va_list * args)
   else
     s = format (s, "%-40s%-25s%=10u", str, app_name, app_wrk->wrk_map_index);
 
-  vec_free (app_name);
   return s;
 }
 
@@ -1983,8 +2057,9 @@ app_worker_format_connects (app_worker_t * app_wrk, int verbose)
   svm_fifo_segment_private_t *fifo_segment;
   vlib_main_t *vm = vlib_get_main ();
   segment_manager_t *sm;
-  u8 *app_name, *s = 0;
+  const u8 *app_name;
   application_t *app;
+  u8 *s = 0;
 
   /* Header */
   if (!app_wrk)
@@ -2001,7 +2076,7 @@ app_worker_format_connects (app_worker_t * app_wrk, int verbose)
   if (app_wrk->connects_seg_manager == (u32) ~ 0)
     return;
 
-  app_name = app_get_name_from_reg_index (app);
+  app_name = app_get_name (app);
 
   /* Across all fifo segments */
   sm = segment_manager_get (app_wrk->connects_seg_manager);
@@ -2039,7 +2114,6 @@ app_worker_format_connects (app_worker_t * app_wrk, int verbose)
   }));
   /* *INDENT-ON* */
 
-  vec_free (app_name);
 }
 
 static void
@@ -2200,8 +2274,7 @@ format_application (u8 * s, va_list * args)
   application_t *app = va_arg (*args, application_t *);
   CLIB_UNUSED (int verbose) = va_arg (*args, int);
   segment_manager_properties_t *props;
-  const u8 *app_ns_name;
-  u8 *app_name;
+  const u8 *app_ns_name, *app_name;
 
   if (app == 0)
     {
diff --git a/src/vnet/session/application.h b/src/vnet/session/application.h
index 3888cf7f463..9c68433d5e9 100644
--- a/src/vnet/session/application.h
+++ b/src/vnet/session/application.h
@@ -101,6 +101,9 @@ typedef struct app_worker_
   /** Hash table of the app's local connects */
   uword *local_connects;
 
+  /** API index for the worker. Needed for multi-process apps */
+  u32 api_index;
+
   u8 app_is_builtin;
 } app_worker_t;
 
@@ -121,7 +124,8 @@ typedef struct application_
   /** App index in app pool */
   u32 app_index;
 
-  /** Binary API connection index, ~0 if internal */
+  /** Binary API connection index of app process that created the app,
+   *  ~0 if internal */
   u32 api_client_index;
 
   /** Flags */
@@ -210,6 +214,7 @@ typedef struct _vnet_app_worker_add_del_args
 {
   u32 app_index;		/**< App for which a new worker is requested */
   u32 wrk_index;		/**< Index to delete or return value if add */
+  u32 api_index;		/**< Binary API client index */
   ssvm_private_t *segment;	/**< First segment in segment manager */
   svm_msg_q_t *evt_q;		/**< Worker message queue */
   u8 is_add;			/**< Flag set if addition */
@@ -251,6 +256,7 @@ int application_stop_listen (u32 app_index, u32 app_or_wrk,
 application_t *application_alloc (void);
 int application_alloc_and_init (app_init_args_t * args);
 void application_free (application_t * app);
+void application_detach_process (application_t * app, u32 api_client_index);
 application_t *application_get (u32 index);
 application_t *application_get_if_valid (u32 index);
 application_t *application_lookup (u32 api_client_index);
@@ -268,7 +274,7 @@ int application_is_builtin (application_t * app);
 int application_is_builtin_proxy (application_t * app);
 u32 application_session_table (application_t * app, u8 fib_proto);
 u32 application_local_session_table (application_t * app);
-u8 *application_name_from_index (u32 app_or_wrk);
+const u8 *application_name_from_index (u32 app_or_wrk);
 u8 application_has_local_scope (application_t * app);
 u8 application_has_global_scope (application_t * app);
 u8 application_use_mq_for_ctrl (application_t * app);
diff --git a/src/vnet/session/application_interface.c b/src/vnet/session/application_interface.c
index 89f74621aa9..3cd8c2f5eb3 100644
--- a/src/vnet/session/application_interface.c
+++ b/src/vnet/session/application_interface.c
@@ -554,7 +554,7 @@ vnet_application_detach (vnet_app_detach_args_t * a)
     }
 
   app_interface_check_thread_and_barrier (vnet_application_detach, a);
-  application_free (app);
+  application_detach_process (app, a->api_client_index);
   return 0;
 }
 
diff --git a/src/vnet/session/application_interface.h b/src/vnet/session/application_interface.h
index dc4c46906c4..10edfdef35a 100644
--- a/src/vnet/session/application_interface.h
+++ b/src/vnet/session/application_interface.h
@@ -33,6 +33,7 @@ typedef struct _vnet_app_attach_args_t
 typedef struct _vnet_app_detach_args_t
 {
   u32 app_index;
+  u32 api_client_index;
 } vnet_app_detach_args_t;
 
 typedef struct _vnet_bind_args_t
diff --git a/src/vnet/session/session_api.c b/src/vnet/session/session_api.c
index 8315c19a7ac..58877010326 100755
--- a/src/vnet/session/session_api.c
+++ b/src/vnet/session/session_api.c
@@ -856,6 +856,7 @@ vl_api_application_detach_t_handler (vl_api_application_detach_t * mp)
   if (app)
     {
       a->app_index = app->app_index;
+      a->api_client_index = mp->client_index;
       rv = vnet_application_detach (a);
     }
 
@@ -1359,6 +1360,7 @@ vl_api_app_worker_add_del_t_handler (vl_api_app_worker_add_del_t * mp)
   vnet_app_worker_add_del_args_t args = {
     .app_index = app->app_index,
     .wrk_index = clib_net_to_host_u32 (mp->wrk_index),
+    .api_index = mp->client_index,
     .is_add = mp->is_add
   };
   error = vnet_app_worker_add_del (&args);
@@ -1732,6 +1734,7 @@ application_reaper_cb (u32 client_index)
   if (app)
     {
       a->app_index = app->app_index;
+      a->api_client_index = client_index;
       vnet_application_detach (a);
     }
   return 0;
diff --git a/src/vnet/session/session_cli.c b/src/vnet/session/session_cli.c
index 651abe17597..3fe49917feb 100755
--- a/src/vnet/session/session_cli.c
+++ b/src/vnet/session/session_cli.c
@@ -205,10 +205,12 @@ show_session_command_fn (vlib_main_t * vm, unformat_input_t * input,
 			 vlib_cli_command_t * cmd)
 {
   session_manager_main_t *smm = &session_manager_main;
-  u8 *str = 0, one_session = 0, do_listeners = 0, sst, *app_name;
-  int verbose = 0, i;
+  u8 *str = 0, one_session = 0, do_listeners = 0, sst;
   stream_session_t *pool, *s;
   u32 transport_proto = ~0;
+  app_worker_t *app_wrk;
+  int verbose = 0, i;
+  const u8 *app_name;
 
   if (!smm->is_enabled)
     {
@@ -248,10 +250,10 @@ show_session_command_fn (vlib_main_t * vm, unformat_input_t * input,
 	if (s->session_state != SESSION_STATE_LISTENING
 	    || s->session_type != sst)
 	  continue;
-	app_name = application_name_from_index (s->app_wrk_index);
+	app_wrk = app_worker_get (s->app_wrk_index);
+	app_name = application_name_from_index (app_wrk->app_index);
 	vlib_cli_output (vm, "%U%-25v%", format_stream_session, s, 1,
 			 app_name);
-	vec_free (app_name);
       }));
       /* *INDENT-ON* */
       return 0;
diff --git a/src/vnet/session/session_lookup.c b/src/vnet/session/session_lookup.c
index 927922e7e64..c410dab121f 100644
--- a/src/vnet/session/session_lookup.c
+++ b/src/vnet/session/session_lookup.c
@@ -1302,9 +1302,10 @@ format_ip4_session_lookup_kvp (u8 * s, va_list * args)
   clib_bihash_kv_16_8_t *kvp = va_arg (*args, clib_bihash_kv_16_8_t *);
   u32 is_local = va_arg (*args, u32), app_wrk_index, session_index;
   v4_connection_key_t *key = (v4_connection_key_t *) kvp->key;
-  u8 *app_name, *str = 0;
   stream_session_t *session;
   app_worker_t *app_wrk;
+  const u8 *app_name;
+  u8 *str = 0;
 
   if (!is_local)
     {
@@ -1327,7 +1328,6 @@ format_ip4_session_lookup_kvp (u8 * s, va_list * args)
 		    clib_net_to_host_u16 (key->src_port));
       s = format (s, "%-30v%-30v", str, app_name);
     }
-  vec_free (app_name);
   return s;
 }