diff --git a/bin/tests/timer_test.c b/bin/tests/timer_test.c
index 023b7b9efc..ea41111102 100644
--- a/bin/tests/timer_test.c
+++ b/bin/tests/timer_test.c
@@ -47,7 +47,7 @@ tick(task_t task, task_event_t event)
 		interval.seconds = 4;
 		interval.nanoseconds = 0;
 		printf("*** resetting ti3 ***\n");
-		INSIST(timer_reset(ti3, timer_type_idle, expires, interval)
+		INSIST(timer_reset(ti3, timer_type_once, expires, interval)
 		       == ISC_R_SUCCESS);
 	}
 
@@ -106,7 +106,7 @@ main(int argc, char *argv[]) {
 	expires.nanoseconds = 0;
 	interval.seconds = 2;
 	interval.nanoseconds = 0;
-	INSIST(timer_create(timgr, timer_type_idle, expires, interval,
+	INSIST(timer_create(timgr, timer_type_once, expires, interval,
 			    t2, timeout, "2", &ti2) == ISC_R_SUCCESS);
 	expires.seconds = 0;
 	expires.nanoseconds = 0;
@@ -119,7 +119,7 @@ main(int argc, char *argv[]) {
 	os_time_add(&now, &expires, &expires);
 	interval.seconds = 2;
 	interval.nanoseconds = 0;
-	INSIST(timer_create(timgr, timer_type_idle, expires, interval,
+	INSIST(timer_create(timgr, timer_type_once, expires, interval,
 			    t3, timeout, "3", &ti3) == ISC_R_SUCCESS);
 
 	task_detach(&t1);
diff --git a/lib/isc/include/isc/timer.h b/lib/isc/include/isc/timer.h
index aadb8bb4ef..dcf3b15bbd 100644
--- a/lib/isc/include/isc/timer.h
+++ b/lib/isc/include/isc/timer.h
@@ -15,10 +15,10 @@
  *
  *	'ticker' timers generate a periodic tick event.
  *
- *	'idle' timers generate an idle timeout event if they are idle for too
+ *	'once' timers generate an idle timeout event if they are idle for too
  *	long, and generate a life timeout event if their lifetime expires.
- *	They are used to implement both expiring idle timers and 'one-shot'
- *	timers.
+ *	They are used to implement both (possibly expiring) idle timers and
+ *	'one-shot' timers.
  *
  * Note: unlike in eventlib, a timer's resources are never reclaimed merely
  * because it generated an event.  A timer reference will remain valid until
@@ -67,7 +67,7 @@ typedef struct timer_t		*timer_t;
 typedef struct timer_manager_t	*timer_manager_t;
 
 typedef enum {
-	timer_type_ticker = 0, timer_type_idle
+	timer_type_ticker = 0, timer_type_once
 } timer_type_t;
 
 typedef struct timer_event {
@@ -107,7 +107,7 @@ timer_create(timer_manager_t manager,
  *	For ticker timers, the timer will generate a 'tick' event every
  *	'interval' seconds.  The value of 'expires' is ignored.
  *
- *	For idle timers, 'expires' specifies the time when a life timeout
+ *	For once timers, 'expires' specifies the time when a life timeout
  *	event should be generated.  If 'expires' is 0, then no life
  *	timeout will be generated.  'interval' specifies how long the timer
  *	can be idle before it generates an idle timeout.  If 0, then no
@@ -131,8 +131,9 @@ timer_create(timer_manager_t manager,
  *
  *	The timer is attached to the task
  *
- *	If 'type' is idle, then the last-touched time is set to the
- *	current time.
+ *	An idle timeout will not be generated until at least Now + the
+ *	timer's interval if 'timer' is a once timer with a non-zero
+ *	interval.
  *
  * Returns:
  *
@@ -159,8 +160,9 @@ timer_reset(timer_t timer,
  *
  * Ensures:
  *
- *	If 'type' is idle, then the last-touched time is set to the
- *	current time.
+ *	An idle timeout will not be generated until at least Now + the
+ *	timer's interval if 'timer' is a once timer with a non-zero
+ *	interval.
  *
  * Returns:
  *
@@ -196,12 +198,13 @@ timer_touch(timer_t timer);
  *
  * Requires:
  *
- *	'timer' is a valid idle timer.
+ *	'timer' is a valid once timer.
  *
  * Ensures:
  *
  *	An idle timeout will not be generated until at least Now + the
- *	timer's interval if 'timer' is an idle timer.
+ *	timer's interval if 'timer' is a once timer with a non-zero
+ *	interval.
  *
  * Returns:
  *
diff --git a/lib/isc/task.c b/lib/isc/task.c
index 38ee8e6b09..bca4a08c10 100644
--- a/lib/isc/task.c
+++ b/lib/isc/task.c
@@ -26,7 +26,7 @@
 #define WAIT(cvp, lp)		INSIST(os_condition_wait((cvp), (lp)))
 #define BROADCAST(cvp)		INSIST(os_condition_broadcast((cvp)))
 
-#ifdef DEBUGTRACE
+#ifdef TASK_TRACE
 #define XTRACE(m)		printf("%s task %p thread %p\n", (m), \
 				       task, os_thread_self())
 #else
diff --git a/lib/isc/timer.c b/lib/isc/timer.c
index 79314614a5..727ff279f6 100644
--- a/lib/isc/timer.c
+++ b/lib/isc/timer.c
@@ -152,10 +152,12 @@ schedule(timer_t timer, os_time_t *nowp, boolean_t broadcast_ok) {
 		manager->nscheduled++;
 	}
 
+#ifdef TIMER_TRACE
 	printf("schedule %p at %lu.%09lu\n",
 	       timer,
 	       (unsigned long)due.seconds,
 	       (unsigned long)due.nanoseconds);
+#endif
 
 	/*
 	 * If this timer is at the head of the queue, we wake up the run
@@ -164,7 +166,9 @@ schedule(timer_t timer, os_time_t *nowp, boolean_t broadcast_ok) {
 	 * want it to oversleep.
 	 */
 	if (timer->index == 1 && broadcast_ok) {
+#ifdef TIMER_TRACE
 		printf("broadcast (schedule)\n");
+#endif
 		BROADCAST(&manager->wakeup);
 	}
 
@@ -189,7 +193,9 @@ deschedule(timer_t timer) {
 		INSIST(manager->nscheduled > 0);
 		manager->nscheduled--;
 		if (need_wakeup) {
+#ifdef TIMER_TRACE
 			printf("broadcast (deschedule)\n");
+#endif
 			BROADCAST(&manager->wakeup);
 		}
 	}
@@ -258,7 +264,7 @@ timer_create(timer_manager_t manager, timer_type_t type,
 	timer->magic = TIMER_MAGIC;
 	timer->manager = manager;
 	timer->references = 1;
-	if (type == timer_type_idle && !ZERO(interval))
+	if (type == timer_type_once && !ZERO(interval))
 		os_time_add(&now, &interval, &timer->idle);
 	else {
 		timer->idle.seconds = 0;
@@ -333,7 +339,7 @@ timer_reset(timer_t timer, timer_type_t type,
 	timer->type = type;
 	timer->expires = expires;
 	timer->interval = interval;
-	if (type == timer_type_idle && !ZERO(interval))
+	if (type == timer_type_once && !ZERO(interval))
 		os_time_add(&now, &interval, &timer->idle);
 	else {
 		timer->idle.seconds = 0;
@@ -385,7 +391,7 @@ timer_touch(timer_t timer) {
 
 	LOCK(&timer->lock);
 
-	INSIST(timer->type == timer_type_idle);
+	INSIST(timer->type == timer_type_once);
 
 	result = os_time_get(&now);
 	if (result != ISC_R_SUCCESS) {
@@ -474,20 +480,25 @@ dispatch(timer_manager_t manager, os_time_t *nowp) {
 				/*
 				 * Idle timer has been touched; reschedule.
 				 */
+#ifdef TIMER_TRACE
 				printf("timer %p idle reschedule\n", timer);
+#endif
 				post_event = FALSE;
 				need_schedule = TRUE;
 			}
 
 			if (post_event) {
+#ifdef TIMER_TRACE
 				printf("timer %p posting %u\n", timer,
 				       type);
+#endif
 				event = task_event_allocate(manager->mctx,
 							    timer,
 							    type,
 							    timer->action,
 							    timer->arg,
 							    sizeof *event);
+
 				if (event != NULL)
 					INSIST(task_send_event(timer->task,
 							       &event));
@@ -524,26 +535,36 @@ run(void *uap) {
 	LOCK(&manager->lock);
 	while (!manager->done) {
 		INSIST(os_time_get(&now) == ISC_R_SUCCESS);
+#ifdef TIMER_TRACE
 		printf("running, now %lu.%09lu\n",
 		       (unsigned long)now.seconds,
 		       (unsigned long)now.nanoseconds);
+#endif
 
 		dispatch(manager, &now);
 
 		if (manager->nscheduled > 0) {
 			ts.tv_sec = manager->due.seconds;
 			ts.tv_nsec = manager->due.nanoseconds;
+#ifdef TIMER_TRACE
 			printf("waituntil %lu.%09lu\n",
 			       (unsigned long)manager->due.seconds,
 			       (unsigned long)manager->due.nanoseconds);
+#endif
 			WAITUNTIL(&manager->wakeup, &manager->lock, &ts,
 				  &timeout);
+#ifdef TIMER_TRACE
 			if (!timeout)
 				printf("wakeup\n");
+#endif
 		} else {
+#ifdef TIMER_TRACE
 			printf("wait\n");
+#endif
 			WAIT(&manager->wakeup, &manager->lock);
+#ifdef TIMER_TRACE
 			printf("wakeup\n");
+#endif
 		}
 	}
 	UNLOCK(&manager->lock);
@@ -628,7 +649,9 @@ timer_manager_destroy(timer_manager_t *managerp) {
 
 	UNLOCK(&manager->lock);
 
+#ifdef TIMER_TRACE
 	printf("broadcast (destroy)\n");
+#endif
 	BROADCAST(&manager->wakeup);
 
 	/*