diff --git a/src/Makefile.in b/src/Makefile.in
index 39bd6d96..37c94d5a 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -98,7 +98,7 @@ install:	libgetdns.la
 
 uninstall:
 	rm -rf $(DESTDIR)$(includedir)/getdns
-	$(LIBTOOL) --mode=uninstall rm -f $(DESTDIR)$(libdir)/libgetdns.la $(EXTENSION_LIBEVENT_LIB) $(EXTENSION_LIBUV_LIB) $(EXTENSION_LIBEV_LIB)
+	$(LIBTOOL) --mode=uninstall rm -f $(DESTDIR)$(libdir)/libgetdns.la $(DESTDIR)$(libdir)/$(EXTENSION_LIBEVENT_LIB) $(DESTDIR)$(libdir)/$(EXTENSION_LIBUV_LIB) $(DESTDIR)$(libdir)/$(EXTENSION_LIBEV_LIB)
 
 libgetdns_ext_event.la: libgetdns.la extension/libevent.lo
 	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) -o $@ extension/libevent.lo ./.libs/libgetdns.la $(EXTENSION_LDFLAGS) $(EXTENSION_LIBEVENT_EXT_LIBS) -rpath $(libdir) -version-info $(libversion) -no-undefined
diff --git a/src/context.c b/src/context.c
index 88d98725..648de5b9 100644
--- a/src/context.c
+++ b/src/context.c
@@ -1183,15 +1183,14 @@ getdns_context_cancel_request(struct getdns_context *context,
         cb = req->user_callback;
         user_pointer = req->user_pointer;
 
-        /* clean up */
-        GETDNS_FREE(context->my_mf, node);
-        dns_req_free(req);
-
         /* fire callback */
         cb(context,
             GETDNS_CALLBACK_CANCEL,
             NULL, user_pointer, transaction_id);
     }
+    /* clean up */
+    GETDNS_FREE(context->my_mf, node);
+    dns_req_free(req);
     return GETDNS_RETURN_GOOD;
 }
 
@@ -1204,7 +1203,12 @@ getdns_cancel_callback(struct getdns_context *context,
     getdns_transaction_t transaction_id)
 {
     RETURN_IF_NULL(context, GETDNS_RETURN_INVALID_PARAMETER);
-    return getdns_context_cancel_request(context, transaction_id, 1);
+    getdns_return_t r = getdns_context_cancel_request(context, transaction_id, 1);
+    if (context->extension) {
+        context->extension->request_count_changed(context,
+            context->outbound_requests->count, context->extension_data);
+    }
+    return r;
 } /* getdns_cancel_callback */
 
 static getdns_return_t
@@ -1384,6 +1388,10 @@ getdns_context_track_outbound_request(getdns_dns_req * req)
         GETDNS_FREE(context->my_mf, node);
         return GETDNS_RETURN_GENERIC_ERROR;
     }
+    if (context->extension) {
+        context->extension->request_count_changed(context,
+            context->outbound_requests->count, context->extension_data);
+    }
     return GETDNS_RETURN_GOOD;
 }
 
@@ -1454,11 +1462,11 @@ int getdns_context_fd(struct getdns_context* context) {
     return ub_fd(context->unbound_ctx);
 }
 
-int
+uint32_t
 getdns_context_get_num_pending_requests(struct getdns_context* context,
     struct timeval* next_timeout) {
     RETURN_IF_NULL(context, GETDNS_RETURN_INVALID_PARAMETER);
-    int r = context->outbound_requests->count;
+    uint32_t r = context->outbound_requests->count;
     if (r > 0) {
         if (!context->extension && next_timeout) {
             /* default is 1 second */
@@ -1697,6 +1705,12 @@ getdns_context_clear_timeout(struct getdns_context* context,
     return GETDNS_RETURN_GOOD;
 }
 
+void*
+getdns_context_get_extension_data(struct getdns_context* context) {
+    RETURN_IF_NULL(context, NULL);
+    return context->extension_data;
+}
+
 static inline getdns_return_t
 priv_dict_set_list_if_not_null(getdns_dict* dict,
     const char* name, getdns_list* list) {
diff --git a/src/extension/libev.c b/src/extension/libev.c
index 6f844629..9bed6aaf 100644
--- a/src/extension/libev.c
+++ b/src/extension/libev.c
@@ -46,20 +46,45 @@ struct getdns_libev_data {
     struct ev_io* poll_handle;
 };
 
-/* lib event callbacks */
+static void
+request_count_changed(uint32_t request_count, struct getdns_libev_data *ev_data) {
+    if (request_count > 0) {
+        ev_io_start(ev_data->loop, ev_data->poll_handle);
+    } else {
+        ev_io_stop(ev_data->loop, ev_data->poll_handle);
+    }
+}
+
+/* lib ev callbacks */
 static void
 getdns_libev_cb(struct ev_loop *loop, struct ev_io *handle, int revents) {
     struct getdns_context* context = (struct getdns_context*) handle->data;
     getdns_context_process_async(context);
+    uint32_t rc = getdns_context_get_num_pending_requests(context, NULL);
+    struct getdns_libev_data* ev_data =
+        (struct getdns_libev_data*) getdns_context_get_extension_data(context);
+    request_count_changed(rc, ev_data);
 }
 
 static void
 getdns_libev_timeout_cb(struct ev_loop *loop, struct ev_timer* handle, int status) {
     getdns_timeout_data_t* timeout_data = (getdns_timeout_data_t*) handle->data;
     timeout_data->callback(timeout_data->userarg);
+    uint32_t rc = getdns_context_get_num_pending_requests(timeout_data->context, NULL);
+    struct getdns_libev_data* ev_data =
+        (struct getdns_libev_data*) getdns_context_get_extension_data(timeout_data->context);
+    request_count_changed(rc, ev_data);
 }
 
 /* getdns extension functions */
+static getdns_return_t
+getdns_libev_request_count_changed(struct getdns_context* context,
+    uint32_t request_count, void* eventloop_data) {
+    struct getdns_libev_data *ev_data = (struct getdns_libev_data*) eventloop_data;
+    request_count_changed(request_count, ev_data);
+    return GETDNS_RETURN_GOOD;
+}
+
 static getdns_return_t
 getdns_libev_cleanup(struct getdns_context* context, void* data) {
     struct getdns_libev_data *ev_data = (struct getdns_libev_data*) data;
@@ -102,7 +127,8 @@ getdns_libev_clear_timeout(struct getdns_context* context,
 static getdns_eventloop_extension LIBEV_EXT = {
     getdns_libev_cleanup,
     getdns_libev_schedule_timeout,
-    getdns_libev_clear_timeout
+    getdns_libev_clear_timeout,
+    getdns_libev_request_count_changed
 };
 
 /*
@@ -129,7 +155,6 @@ getdns_extension_set_libev_loop(struct getdns_context *context,
     ev_io_init(ev_data->poll_handle, getdns_libev_cb, fd, EV_READ);
     ev_data->loop = loop;
 
-    ev_io_start(ev_data->loop, ev_data->poll_handle);
     ev_data->poll_handle->data = context;
     return getdns_extension_set_eventloop(context, &LIBEV_EXT, ev_data);
 }               /* getdns_extension_set_libev_loop */
diff --git a/src/extension/libevent.c b/src/extension/libevent.c
index 41f508c4..f030271e 100644
--- a/src/extension/libevent.c
+++ b/src/extension/libevent.c
@@ -72,20 +72,45 @@ struct event_data {
     struct event_base* event_base;
 };
 
+static void
+request_count_changed(uint32_t request_count, struct event_data *ev_data) {
+    if (request_count > 0) {
+        event_add(ev_data->event, NULL);
+    } else {
+        event_del(ev_data->event);
+    }
+}
+
 /* lib event callbacks */
 static void
 getdns_libevent_cb(evutil_socket_t fd, short what, void *userarg) {
     struct getdns_context* context = (struct getdns_context*) userarg;
     getdns_context_process_async(context);
+    uint32_t rc = getdns_context_get_num_pending_requests(context, NULL);
+    struct event_data* ev_data =
+        (struct event_data*) getdns_context_get_extension_data(context);
+    request_count_changed(rc, ev_data);
 }
 
 static void
 getdns_libevent_timeout_cb(evutil_socket_t fd, short what, void* userarg) {
     getdns_timeout_data_t* timeout_data = (getdns_timeout_data_t*) userarg;
     timeout_data->callback(timeout_data->userarg);
+    uint32_t rc = getdns_context_get_num_pending_requests(timeout_data->context, NULL);
+    struct event_data* ev_data =
+        (struct event_data*) getdns_context_get_extension_data(timeout_data->context);
+    request_count_changed(rc, ev_data);
 }
 
 /* getdns extension functions */
+static getdns_return_t
+getdns_libevent_request_count_changed(struct getdns_context* context,
+    uint32_t request_count, void* eventloop_data) {
+    struct event_data *edata = (struct event_data*) eventloop_data;
+    request_count_changed(request_count, edata);
+    return GETDNS_RETURN_GOOD;
+}
+
 static getdns_return_t
 getdns_libevent_cleanup(struct getdns_context* context, void* data) {
     struct event_data *edata = (struct event_data*) data;
@@ -128,7 +153,8 @@ getdns_libevent_clear_timeout(struct getdns_context* context,
 static getdns_eventloop_extension LIBEVENT_EXT = {
     getdns_libevent_cleanup,
     getdns_libevent_schedule_timeout,
-    getdns_libevent_clear_timeout
+    getdns_libevent_clear_timeout,
+    getdns_libevent_request_count_changed
 };
 
 /*
@@ -151,7 +177,6 @@ getdns_extension_set_libevent_base(struct getdns_context *context,
     if (!getdns_event) {
         return GETDNS_RETURN_GENERIC_ERROR;
     }
-    event_add(getdns_event, NULL);
 
     /* TODO: use context functs? */
     struct event_data* ev_data = (struct event_data*) malloc(sizeof(struct event_data));
@@ -163,6 +188,5 @@ getdns_extension_set_libevent_base(struct getdns_context *context,
     }
     ev_data->event = getdns_event;
     ev_data->event_base = this_event_base;
-
     return getdns_extension_set_eventloop(context, &LIBEVENT_EXT, ev_data);
 }               /* getdns_extension_set_libevent_base */
diff --git a/src/extension/libuv.c b/src/extension/libuv.c
index 8646e7e1..583ba263 100644
--- a/src/extension/libuv.c
+++ b/src/extension/libuv.c
@@ -44,19 +44,41 @@
 struct getdns_libuv_data {
     uv_loop_t* loop;
     uv_poll_t* poll_handle;
+    uint8_t polling;
 };
 
+static void request_count_changed(uint32_t request_count, struct getdns_libuv_data *uv_data);
+
 /* lib event callbacks */
 static void
 getdns_libuv_cb(uv_poll_t* handle, int status, int events) {
     struct getdns_context* context = (struct getdns_context*) handle->data;
     getdns_context_process_async(context);
+    uint32_t rc = getdns_context_get_num_pending_requests(context, NULL);
+    struct getdns_libuv_data* uv_data =
+        (struct getdns_libuv_data*) getdns_context_get_extension_data(context);
+    request_count_changed(rc, uv_data);
+}
+
+static void
+request_count_changed(uint32_t request_count, struct getdns_libuv_data *uv_data) {
+    if (request_count > 0 && uv_data->polling == 0) {
+        uv_poll_start(uv_data->poll_handle, UV_READABLE, getdns_libuv_cb);
+        uv_data->polling = 1;
+    } else if (request_count == 0 && uv_data->polling == 1) {
+        uv_poll_stop(uv_data->poll_handle);
+        uv_data->polling = 0;
+    }
 }
 
 static void
 getdns_libuv_timeout_cb(uv_timer_t* handle, int status) {
     getdns_timeout_data_t* timeout_data = (getdns_timeout_data_t*) handle->data;
     timeout_data->callback(timeout_data->userarg);
+    uint32_t rc = getdns_context_get_num_pending_requests(timeout_data->context, NULL);
+    struct getdns_libuv_data* uv_data =
+        (struct getdns_libuv_data*) getdns_context_get_extension_data(timeout_data->context);
+    request_count_changed(rc, uv_data);
 }
 
 static void
@@ -67,6 +89,14 @@ getdns_libuv_close_cb(uv_handle_t* handle) {
 }
 
 /* getdns extension functions */
+static getdns_return_t
+getdns_libuv_request_count_changed(struct getdns_context* context,
+    uint32_t request_count, void* eventloop_data) {
+    struct getdns_libuv_data *edata = (struct getdns_libuv_data*) eventloop_data;
+    request_count_changed(request_count, edata);
+    return GETDNS_RETURN_GOOD;
+}
+
 static getdns_return_t
 getdns_libuv_cleanup(struct getdns_context* context, void* data) {
     struct getdns_libuv_data *uv_data = (struct getdns_libuv_data*) data;
@@ -108,7 +138,8 @@ getdns_libuv_clear_timeout(struct getdns_context* context,
 static getdns_eventloop_extension LIBUV_EXT = {
     getdns_libuv_cleanup,
     getdns_libuv_schedule_timeout,
-    getdns_libuv_clear_timeout
+    getdns_libuv_clear_timeout,
+    getdns_libuv_request_count_changed
 };
 
 /*
@@ -135,7 +166,6 @@ getdns_extension_set_libuv_loop(struct getdns_context *context,
     uv_poll_init(uv_loop, uv_data->poll_handle, fd);
     uv_data->poll_handle->data = context;
     uv_data->loop = uv_loop;
-
-    uv_poll_start(uv_data->poll_handle, UV_READABLE, getdns_libuv_cb);
+    uv_data->polling = 0;
     return getdns_extension_set_eventloop(context, &LIBUV_EXT, uv_data);
 }               /* getdns_extension_set_libuv_loop */
diff --git a/src/general.c b/src/general.c
index 86f7a380..243106a4 100644
--- a/src/general.c
+++ b/src/general.c
@@ -74,12 +74,9 @@ ub_resolve_timeout(void *arg)
 	getdns_callback_t cb = dns_req->user_callback;
 	void *user_arg = dns_req->user_pointer;
 
-	/* cancel the req - also clears it from outbound */
+	/* cancel the req - also clears it from outbound and cleans up*/
 	getdns_context_cancel_request(context, trans_id, 0);
 
-	/* cleanup */
-	dns_req_free(dns_req);
-
 	cb(context, GETDNS_CALLBACK_TIMEOUT, NULL, user_arg, trans_id);
 }
 
diff --git a/src/getdns/getdns.h.in b/src/getdns/getdns.h.in
index 4c37f750..d8bcb586 100644
--- a/src/getdns/getdns.h.in
+++ b/src/getdns/getdns.h.in
@@ -1009,16 +1009,6 @@ getdns_context_set_extended_memory_functions(getdns_context *context,
 getdns_dict*
 getdns_context_get_api_information(getdns_context* context);
 
-/* Async support */
-struct timeval;
-int getdns_context_get_num_pending_requests(getdns_context* context, struct timeval* next_timeout);
-
-/* get the fd */
-int getdns_context_fd(getdns_context* context);
-
-/* process async reqs */
-getdns_return_t getdns_context_process_async(getdns_context* context);
-
 /* Get root trust anchor */
 getdns_list *getdns_root_trust_anchor(time_t *utc_date_of_anchor);
 
diff --git a/src/getdns/getdns_extra.h b/src/getdns/getdns_extra.h
index 12c1ca58..8d8494fd 100644
--- a/src/getdns/getdns_extra.h
+++ b/src/getdns/getdns_extra.h
@@ -42,12 +42,12 @@ getdns_return_t getdns_context_set_return_dnssec_status(getdns_context* context,
 getdns_return_t getdns_dict_util_set_string(struct getdns_dict * dict, char *name,
     const char *value);
 
-/* get a string from a dict.  result is valid as long as dict is valid */
+/* get a string from a dict.  the result must be freed if valid */
 getdns_return_t getdns_dict_util_get_string(struct getdns_dict * dict, char *name,
     char **result);
 
 /* Async support */
-int getdns_context_get_num_pending_requests(getdns_context* context, struct timeval* next_timeout);
+uint32_t getdns_context_get_num_pending_requests(getdns_context* context, struct timeval* next_timeout);
 
 /* get the fd */
 int getdns_context_fd(getdns_context* context);
@@ -61,33 +61,57 @@ typedef void (*getdns_timeout_callback) (void* userarg);
 
 /* context timeout data */
 typedef struct getdns_timeout_data {
+    /* a timeout id */
     getdns_transaction_t transaction_id;
+    /* the absolute time of the timeout */
     struct timeval timeout_time;
+    /* the timeout callback to fire */
     getdns_timeout_callback callback;
+    /* timeout callback user arg */
     void* userarg;
+    /* pointer to the underlying extension pointer that the extension
+       will create and free */
     void* extension_timer;
+    /* context */
     struct getdns_context* context;
 } getdns_timeout_data_t;
 
+/* call the extension when the data needs to be cleaned up */
 typedef getdns_return_t (*getdns_eventloop_cleanup_t)(struct getdns_context* context, void* eventloop_data);
+
+/* call the extension to schedule a timer.  Any timer data that needs to be tracked should be
+   stored in eventloop_timer */
 typedef getdns_return_t (*getdns_eventloop_schedule_timeout_t)(struct getdns_context* context,
     void* eventloop_data, uint16_t timeout,
     getdns_timeout_data_t* timeout_data,
     void** eventloop_timer);
+
+/* call the extension to free a timer.  The timer passed in is the same as that returned in
+   the schedule timeout */
 typedef getdns_return_t (*getdns_eventloop_clear_timeout_t)(struct getdns_context* context,
     void* eventloop_data, void* eventloop_timer);
 
+/* call the extension to tell it that the number of outbound requests changed.  This is called
+   when an async request is submitted or canceled by the user */
+typedef getdns_return_t (*getdns_eventloop_request_count_changed_t)(struct getdns_context* context,
+    uint32_t request_count, void* eventloop_data);
 
 typedef struct getdns_eventloop_extension {
     getdns_eventloop_cleanup_t cleanup_data;
     getdns_eventloop_schedule_timeout_t schedule_timeout;
     getdns_eventloop_clear_timeout_t clear_timeout;
+    getdns_eventloop_request_count_changed_t request_count_changed;
 } getdns_eventloop_extension;
 
-/* extension stuff */
-getdns_return_t getdns_extension_set_eventloop(struct getdns_context* context,
+/* set an event loop extension on the context */
+getdns_return_t
+getdns_extension_set_eventloop(struct getdns_context* context,
     getdns_eventloop_extension* extension, void* extension_data);
 
+void*
+getdns_context_get_extension_data(struct getdns_context* context);
+
+/* detach the eventloop from the context */
 getdns_return_t
 getdns_extension_detach_eventloop(struct getdns_context* context);
 
diff --git a/src/test/Makefile.in b/src/test/Makefile.in
index fe209368..d614471a 100644
--- a/src/test/Makefile.in
+++ b/src/test/Makefile.in
@@ -82,16 +82,16 @@ check_getdns_common: check_getdns_common.o
 	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) $(LDFLAGS) $(LDLIBS) -o $@ check_getdns_common.o
 
 check_getdns: check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_selectloop.o
-	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) $(LDFLAGS) $(LDLIBS)  -o $@ check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_selectloop.o
+	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) $(LDFLAGS) $(LDLIBS) -lpthread -o $@ check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_selectloop.o
 
 check_getdns_event: check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_libevent.o
-	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) $(LDFLAGS) -lgetdns_ext_event $(EXTENSION_LIBEVENT_EXT_LIBS) $(LDLIBS)  -o $@ check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_libevent.o
+	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) $(LDFLAGS) -lpthread -lgetdns_ext_event $(EXTENSION_LIBEVENT_EXT_LIBS) $(LDLIBS)  -o $@ check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_libevent.o
 
 check_getdns_uv: check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_libuv.o
-	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) $(LDFLAGS) -lgetdns_ext_uv $(EXTENSION_LIBUV_EXT_LIBS) $(LDLIBS)  -o $@ check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_libuv.o
+	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) $(LDFLAGS) -lpthread -lgetdns_ext_uv $(EXTENSION_LIBUV_EXT_LIBS) $(LDLIBS)  -o $@ check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_libuv.o
 
 check_getdns_ev: check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_libev.o
-	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) $(LDFLAGS) -lgetdns_ext_ev $(EXTENSION_LIBEV_EXT_LIBS) $(LDLIBS)  -o $@ check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_libev.o
+	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) $(LDFLAGS) -lpthread -lgetdns_ext_ev $(EXTENSION_LIBEV_EXT_LIBS) $(LDLIBS)  -o $@ check_getdns.o check_getdns_common.o check_getdns_context_set_timeout.o check_getdns_libev.o
 
 tests_dnssec: tests_dnssec.o testmessages.o
 	$(LIBTOOL) --tag=CC --mode=link $(CC) $(CFLAGS) $(LDFLAGS) -lgetdns_ext_event $(LDLIBS) -o $@ tests_dnssec.o testmessages.o
diff --git a/src/test/check_getdns_libev.c b/src/test/check_getdns_libev.c
index 6a5b2455..c3dff023 100644
--- a/src/test/check_getdns_libev.c
+++ b/src/test/check_getdns_libev.c
@@ -42,9 +42,7 @@
 
 void run_event_loop_impl(struct getdns_context* context, void* eventloop) {
     struct ev_loop* loop = (struct ev_loop*) eventloop;
-    while (getdns_context_get_num_pending_requests(context, NULL) > 0) {
-        ev_run(loop, EVRUN_ONCE);
-    }
+    ev_run(loop, 0);
 }
 
 void* create_eventloop_impl(struct getdns_context* context) {
diff --git a/src/test/check_getdns_libevent.c b/src/test/check_getdns_libevent.c
index d2d39c03..a83bd551 100644
--- a/src/test/check_getdns_libevent.c
+++ b/src/test/check_getdns_libevent.c
@@ -42,9 +42,7 @@
 
 void run_event_loop_impl(struct getdns_context* context, void* eventloop) {
     struct event_base* base = (struct event_base*) eventloop;
-    while (getdns_context_get_num_pending_requests(context, NULL) > 0) {
-        event_base_loop(base, EVLOOP_ONCE);
-    }
+    event_base_dispatch(base);
 }
 
 void* create_eventloop_impl(struct getdns_context* context) {
diff --git a/src/test/check_getdns_libuv.c b/src/test/check_getdns_libuv.c
index c1ffcf77..4994cae7 100644
--- a/src/test/check_getdns_libuv.c
+++ b/src/test/check_getdns_libuv.c
@@ -42,9 +42,7 @@
 
 void run_event_loop_impl(struct getdns_context* context, void* eventloop) {
     uv_loop_t* loop = (uv_loop_t*) eventloop;
-    while (getdns_context_get_num_pending_requests(context, NULL) > 0) {
-        uv_run(loop, UV_RUN_ONCE);
-    }
+    uv_run(loop, UV_RUN_DEFAULT);
 }