diff --git a/src/vpp-api/python/pneum/pneum.c b/src/vpp-api/python/pneum/pneum.c
index 37c8d8f..da9d69d 100644
--- a/src/vpp-api/python/pneum/pneum.c
+++ b/src/vpp-api/python/pneum/pneum.c
@@ -22,9 +22,7 @@
 #include <netinet/in.h>
 #include <netdb.h>
 #include <signal.h>
-#include <setjmp.h>
 #include <stdbool.h>
-
 #include <vnet/vnet.h>
 #include <vlib/vlib.h>
 #include <vlib/unix/unix.h>
@@ -35,6 +33,16 @@
 
 #include "pneum.h"
 
+/*
+ * Asynchronous mode:
+ *  Client registers a callback. All messages are sent to the callback.
+ * Synchronous mode:
+ *  Client calls blocking read().
+ *  Clients are expected to collate events on a queue.
+ *  pneum_write() -> suspends RX thread
+ *  pneum_read() -> resumes RX thread
+ */
+
 #define vl_typedefs             /* define message structures */
 #include <vpp/api/vpe_all_api_h.h>
 #undef vl_typedefs
@@ -47,15 +55,50 @@
 vlib_main_t **vlib_mains;
 
 typedef struct {
-  u8 rx_thread_jmpbuf_valid;
   u8 connected_to_vlib;
-  jmp_buf rx_thread_jmpbuf;
   pthread_t rx_thread_handle;
+  pthread_t timeout_thread_handle;
+  pthread_mutex_t queue_lock;
+  pthread_cond_t suspend_cv;
+  pthread_cond_t resume_cv;
+  pthread_mutex_t timeout_lock;
+  pthread_cond_t timeout_cv;
+  pthread_cond_t timeout_cancel_cv;
+  pthread_cond_t terminate_cv;
 } pneum_main_t;
 
 pneum_main_t pneum_main;
-
 pneum_callback_t pneum_callback;
+u16 read_timeout = 0;
+bool rx_is_running = false;
+
+static void
+init (void)
+{
+  pneum_main_t *pm = &pneum_main;
+  memset(pm, 0, sizeof(*pm));
+  pthread_mutex_init(&pm->queue_lock, NULL);
+  pthread_cond_init(&pm->suspend_cv, NULL);
+  pthread_cond_init(&pm->resume_cv, NULL);
+  pthread_mutex_init(&pm->timeout_lock, NULL);
+  pthread_cond_init(&pm->timeout_cv, NULL);
+  pthread_cond_init(&pm->timeout_cancel_cv, NULL);
+  pthread_cond_init(&pm->terminate_cv, NULL);
+}
+
+static void
+cleanup (void)
+{
+  pneum_main_t *pm = &pneum_main;
+  pthread_cond_destroy(&pm->suspend_cv);
+  pthread_cond_destroy(&pm->resume_cv);
+  pthread_cond_destroy(&pm->timeout_cv);
+  pthread_cond_destroy(&pm->timeout_cancel_cv);
+  pthread_cond_destroy(&pm->terminate_cv);
+  pthread_mutex_destroy(&pm->queue_lock);
+  pthread_mutex_destroy(&pm->timeout_lock);
+  memset (pm, 0, sizeof (*pm));
+}
 
 /*
  * Satisfy external references when -lvlib is not available.
@@ -75,11 +118,6 @@
 pneum_api_handler (void *msg)
 {
   u16 id = ntohs(*((u16 *)msg));
-  if (id == VL_API_RX_THREAD_EXIT) {
-    pneum_main_t *pm = &pneum_main;
-    vl_msg_api_free(msg);
-    longjmp(pm->rx_thread_jmpbuf, 1);
-  }
   msgbuf_t *msgbuf = (msgbuf_t *)(((u8 *)msg) - offsetof(msgbuf_t, data));
   int l = ntohl(msgbuf->data_len);
   if (l == 0)
@@ -101,16 +139,108 @@
 
   q = am->vl_input_queue;
 
-  /* So we can make the rx thread terminate cleanly */
-  if (setjmp(pm->rx_thread_jmpbuf) == 0) {
-    pm->rx_thread_jmpbuf_valid = 1;
-    while (1)
-      while (!unix_shared_memory_queue_sub(q, (u8 *)&msg, 0))
-        pneum_api_handler((void *)msg);
-  }
+  while (1)
+    while (!unix_shared_memory_queue_sub(q, (u8 *)&msg, 0))
+      {
+	u16 id = ntohs(*((u16 *)msg));
+	switch (id) {
+	case VL_API_RX_THREAD_EXIT:
+	  vl_msg_api_free((void *) msg);
+	  /* signal waiting threads that this thread is about to terminate */
+	  pthread_mutex_lock(&pm->queue_lock);
+	  pthread_cond_signal(&pm->terminate_cv);
+	  pthread_mutex_unlock(&pm->queue_lock);
+	  pthread_exit(0);
+	  return 0;
+	  break;
+
+	case VL_API_MEMCLNT_RX_THREAD_SUSPEND:
+	  vl_msg_api_free((void * )msg);
+	  /* Suspend thread and signal reader */
+	  pthread_mutex_lock(&pm->queue_lock);
+	  pthread_cond_signal(&pm->suspend_cv);
+	  /* Wait for the resume signal */
+	  pthread_cond_wait (&pm->resume_cv, &pm->queue_lock);
+	  pthread_mutex_unlock(&pm->queue_lock);
+	  break;
+
+	case VL_API_MEMCLNT_READ_TIMEOUT:
+	  clib_warning("Received read timeout in async thread\n");
+	  vl_msg_api_free((void *) msg);
+	  break;
+
+	default:
+	  pneum_api_handler((void *)msg);
+	}
+      }
+}
+
+static void *
+pneum_timeout_thread_fn (void *arg)
+{
+  vl_api_memclnt_read_timeout_t *ep;
+  pneum_main_t *pm = &pneum_main;
+  api_main_t *am = &api_main;
+  struct timespec ts;
+  struct timeval tv;
+  u16 timeout;
+  int rv;
+
+  while (1)
+    {
+      /* Wait for poke */
+      pthread_mutex_lock(&pm->timeout_lock);
+      pthread_cond_wait (&pm->timeout_cv, &pm->timeout_lock);
+      timeout = read_timeout;
+      gettimeofday(&tv, NULL);
+      ts.tv_sec = tv.tv_sec + timeout;
+      ts.tv_nsec = 0;
+      rv = pthread_cond_timedwait (&pm->timeout_cancel_cv,
+				   &pm->timeout_lock, &ts);
+      pthread_mutex_unlock(&pm->timeout_lock);
+      if (rv == ETIMEDOUT)
+	{
+	  ep = vl_msg_api_alloc (sizeof (*ep));
+	  ep->_vl_msg_id = ntohs(VL_API_MEMCLNT_READ_TIMEOUT);
+	  vl_msg_api_send_shmem(am->vl_input_queue, (u8 *)&ep);
+	}
+    }
   pthread_exit(0);
 }
 
+void
+pneum_rx_suspend (void)
+{
+  api_main_t *am = &api_main;
+  pneum_main_t *pm = &pneum_main;
+  vl_api_memclnt_rx_thread_suspend_t *ep;
+
+  if (!pm->rx_thread_handle) return;
+  pthread_mutex_lock(&pm->queue_lock);
+  if (rx_is_running)
+    {
+      ep = vl_msg_api_alloc (sizeof (*ep));
+      ep->_vl_msg_id = ntohs(VL_API_MEMCLNT_RX_THREAD_SUSPEND);
+      vl_msg_api_send_shmem(am->vl_input_queue, (u8 *)&ep);
+      /* Wait for RX thread to tell us it has suspendend */
+      pthread_cond_wait(&pm->suspend_cv, &pm->queue_lock);
+      rx_is_running = false;
+    }
+  pthread_mutex_unlock(&pm->queue_lock);
+}
+
+void
+pneum_rx_resume (void)
+{
+  pneum_main_t *pm = &pneum_main;
+  if (!pm->rx_thread_handle) return;
+  pthread_mutex_lock(&pm->queue_lock);
+  if (rx_is_running) return;
+  pthread_cond_signal(&pm->resume_cv);
+  rx_is_running = true;
+  pthread_mutex_unlock(&pm->queue_lock);
+}
+
 uword *
 pneum_msg_table_get_hash (void)
 {
@@ -126,12 +256,13 @@
 }
 
 int
-pneum_connect (char * name, char * chroot_prefix, pneum_callback_t cb, 
+pneum_connect (char * name, char * chroot_prefix, pneum_callback_t cb,
                int rx_qlen)
 {
   int rv = 0;
   pneum_main_t *pm = &pneum_main;
 
+  init();
   if (chroot_prefix != NULL)
     vl_set_memory_root_path (chroot_prefix);
 
@@ -154,6 +285,16 @@
       return (-1);
     }
     pneum_callback = cb;
+    rx_is_running = true;
+  }
+
+  /* Start read timeout thread */
+  rv = pthread_create(&pm->timeout_thread_handle, NULL,
+		      pneum_timeout_thread_fn, 0);
+  if (rv) {
+    clib_warning("pthread_create returned %d", rv);
+    vl_client_api_unmap();
+    return (-1);
   }
 
   pm->connected_to_vlib = 1;
@@ -167,31 +308,69 @@
   api_main_t *am = &api_main;
   pneum_main_t *pm = &pneum_main;
 
-  if (pm->rx_thread_jmpbuf_valid) {
+  if (!pm->connected_to_vlib) return 0;
+
+  if (pm->rx_thread_handle) {
     vl_api_rx_thread_exit_t *ep;
     uword junk;
     ep = vl_msg_api_alloc (sizeof (*ep));
     ep->_vl_msg_id = ntohs(VL_API_RX_THREAD_EXIT);
     vl_msg_api_send_shmem(am->vl_input_queue, (u8 *)&ep);
-    pthread_join(pm->rx_thread_handle, (void **) &junk);
+
+    /* wait (with timeout) until RX thread has finished */
+    struct timespec ts;
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    ts.tv_sec = tv.tv_sec + 5;
+    ts.tv_nsec = 0;
+    pthread_mutex_lock(&pm->queue_lock);
+    int rv = pthread_cond_timedwait(&pm->terminate_cv, &pm->queue_lock, &ts);
+    pthread_mutex_unlock(&pm->queue_lock);
+    /* now join so we wait until thread has -really- finished */
+    if (rv == ETIMEDOUT)
+      pthread_cancel(pm->rx_thread_handle);
+    else
+      pthread_join(pm->rx_thread_handle, (void **) &junk);
   }
-  if (pm->connected_to_vlib) {
-    vl_client_disconnect();
-    vl_client_api_unmap();
-    pneum_callback = 0;
-  }
-  memset (pm, 0, sizeof (*pm));
+  if (pm->timeout_thread_handle)
+    pthread_cancel(pm->timeout_thread_handle);
+
+  vl_client_disconnect();
+  vl_client_api_unmap();
+  pneum_callback = 0;
+
+  cleanup();
 
   return (0);
 }
 
+static void
+set_timeout (unsigned short timeout)
+{
+  pneum_main_t *pm = &pneum_main;
+  pthread_mutex_lock(&pm->timeout_lock);
+  read_timeout = timeout;
+  pthread_cond_signal(&pm->timeout_cv);
+  pthread_mutex_unlock(&pm->timeout_lock);
+}
+
+static void
+unset_timeout (void)
+{
+  pneum_main_t *pm = &pneum_main;
+  pthread_mutex_lock(&pm->timeout_lock);
+  pthread_cond_signal(&pm->timeout_cancel_cv);
+  pthread_mutex_unlock(&pm->timeout_lock);
+}
+
 int
-pneum_read (char **p, int *l)
+pneum_read (char **p, int *l, u16 timeout)
 {
   unix_shared_memory_queue_t *q;
   api_main_t *am = &api_main;
   pneum_main_t *pm = &pneum_main;
   uword msg;
+  msgbuf_t *msgbuf;
 
   if (!pm->connected_to_vlib) return -1;
 
@@ -199,21 +378,48 @@
 
   if (am->our_pid == 0) return (-1);
 
+  /* Poke timeout thread */
+  if (timeout)
+    set_timeout(timeout);
+
   q = am->vl_input_queue;
   int rv = unix_shared_memory_queue_sub(q, (u8 *)&msg, 0);
   if (rv == 0) {
     u16 msg_id = ntohs(*((u16 *)msg));
-    msgbuf_t *msgbuf = (msgbuf_t *)(((u8 *)msg) - offsetof(msgbuf_t, data));
-    *l = ntohl(msgbuf->data_len);
-    if (*l == 0) {
-      printf("Unregistered API message: %d\n", msg_id);
-      return (-1);
+    switch (msg_id) {
+    case VL_API_RX_THREAD_EXIT:
+      printf("Received thread exit\n");
+      return -1;
+    case VL_API_MEMCLNT_RX_THREAD_SUSPEND:
+      printf("Received thread suspend\n");
+      goto error;
+    case VL_API_MEMCLNT_READ_TIMEOUT:
+      printf("Received read timeout %ds\n", timeout);
+      goto error;
+
+    default:
+      msgbuf = (msgbuf_t *)(((u8 *)msg) - offsetof(msgbuf_t, data));
+      *l = ntohl(msgbuf->data_len);
+      if (*l == 0) {
+	printf("Unregistered API message: %d\n", msg_id);
+	goto error;
+      }
     }
     *p = (char *)msg;
+
+    /* Let timeout notification thread know we're done */
+    unset_timeout();
+
   } else {
     printf("Read failed with %d\n", rv);
   }
   return (rv);
+
+ error:
+  vl_msg_api_free((void *) msg);
+  /* Client might forget to resume RX thread on failure */
+  pneum_rx_resume ();
+  return -1;
 }
 
 /*
@@ -241,12 +447,13 @@
 
   if (!pm->connected_to_vlib) return -1;
   if (!mp) return (-1);
+
   memcpy(mp, p, l);
   mp->client_index = pneum_client_index();
   q = am->shmem_hdr->vl_input_queue;
   rv = unix_shared_memory_queue_add(q, (u8 *)&mp, 0);
   if (rv != 0) {
-    printf("vpe_api_write fails: %d\n", rv);
+    clib_warning("vpe_api_write fails: %d\n", rv);
     /* Clear message */
     pneum_free(mp);
   }
diff --git a/src/vpp-api/python/pneum/pneum.h b/src/vpp-api/python/pneum/pneum.h
index 9312eb4..c4b55ae 100644
--- a/src/vpp-api/python/pneum/pneum.h
+++ b/src/vpp-api/python/pneum/pneum.h
@@ -22,11 +22,13 @@
 int pneum_connect(char * name, char * chroot_prefix, pneum_callback_t cb,
     int rx_qlen);
 int pneum_disconnect(void);
-int pneum_read(char **data, int *l);
+int pneum_read(char **data, int *l, unsigned short timeout);
 int pneum_write(char *data, int len);
 void pneum_free(void * msg);
 uword * pneum_msg_table_get_hash (void);
 int pneum_msg_table_size(void);
 uint32_t pneum_get_msg_index(unsigned char * name);
+void pneum_rx_suspend (void);
+void pneum_rx_resume (void);
 
 #endif