diff --git a/lib/dns/cache.c b/lib/dns/cache.c
index f69b2f912b..b5d2b0995f 100644
--- a/lib/dns/cache.c
+++ b/lib/dns/cache.c
@@ -131,6 +131,7 @@ struct dns_cache {
 	isc_mutex_t filelock;
 	isc_mem_t *mctx;  /* Main cache memory */
 	isc_mem_t *hmctx; /* Heap memory */
+	isc_taskmgr_t *taskmgr;
 	char *name;
 	isc_refcount_t references;
 	isc_refcount_t live_tasks;
@@ -172,12 +173,46 @@ overmem_cleaning_action(isc_task_t *task, isc_event_t *event);
 static isc_result_t
 cache_create_db(dns_cache_t *cache, dns_db_t **db) {
 	isc_result_t result;
+	isc_task_t *dbtask = NULL;
+	isc_task_t *prunetask = NULL;
+
 	result = dns_db_create(cache->mctx, cache->db_type, dns_rootname,
 			       dns_dbtype_cache, cache->rdclass, cache->db_argc,
 			       cache->db_argv, db);
-	if (result == ISC_R_SUCCESS) {
-		dns_db_setservestalettl(*db, cache->serve_stale_ttl);
+	if (result != ISC_R_SUCCESS) {
+		return (result);
 	}
+
+	dns_db_setservestalettl(*db, cache->serve_stale_ttl);
+
+	if (cache->taskmgr == NULL) {
+		return (ISC_R_SUCCESS);
+	}
+
+	result = isc_task_create(cache->taskmgr, 1, &dbtask);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup_db;
+	}
+	isc_task_setname(dbtask, "cache_dbtask", NULL);
+
+	result = isc_task_create(cache->taskmgr, UINT_MAX, &prunetask);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup_dbtask;
+	}
+	isc_task_setname(prunetask, "cache_prunetask", NULL);
+
+	dns_db_settask(*db, dbtask, prunetask);
+
+	isc_task_detach(&prunetask);
+	isc_task_detach(&dbtask);
+
+	return (ISC_R_SUCCESS);
+
+cleanup_dbtask:
+	isc_task_detach(&dbtask);
+cleanup_db:
+	dns_db_detach(db);
+
 	return (result);
 }
 
@@ -194,6 +229,7 @@ dns_cache_create(isc_mem_t *cmctx, isc_mem_t *hmctx, isc_taskmgr_t *taskmgr,
 	REQUIRE(*cachep == NULL);
 	REQUIRE(cmctx != NULL);
 	REQUIRE(hmctx != NULL);
+	REQUIRE(taskmgr != NULL || strcmp(db_type, "rbt") != 0);
 	REQUIRE(cachename != NULL);
 
 	cache = isc_mem_get(cmctx, sizeof(*cache));
@@ -202,6 +238,11 @@ dns_cache_create(isc_mem_t *cmctx, isc_mem_t *hmctx, isc_taskmgr_t *taskmgr,
 	isc_mem_attach(cmctx, &cache->mctx);
 	isc_mem_attach(hmctx, &cache->hmctx);
 
+	cache->taskmgr = NULL;
+	if (taskmgr != NULL) {
+		isc_taskmgr_attach(taskmgr, &cache->taskmgr);
+	}
+
 	cache->name = NULL;
 	if (cachename != NULL) {
 		cache->name = isc_mem_strdup(cmctx, cachename);
@@ -259,27 +300,6 @@ dns_cache_create(isc_mem_t *cmctx, isc_mem_t *hmctx, isc_taskmgr_t *taskmgr,
 	if (result != ISC_R_SUCCESS) {
 		goto cleanup_dbargv;
 	}
-	if (taskmgr != NULL) {
-		isc_task_t *dbtask = NULL;
-		isc_task_t *prunetask = NULL;
-
-		result = isc_task_create(taskmgr, 1, &dbtask);
-		if (result != ISC_R_SUCCESS) {
-			goto cleanup_db;
-		}
-		isc_task_setname(dbtask, "cache_dbtask", NULL);
-
-		result = isc_task_create(taskmgr, UINT_MAX, &prunetask);
-		if (result != ISC_R_SUCCESS) {
-			isc_task_detach(&dbtask);
-			goto cleanup_db;
-		}
-		isc_task_setname(prunetask, "cache_prunetask", NULL);
-
-		dns_db_settask(cache->db, dbtask, prunetask);
-		isc_task_detach(&dbtask);
-		isc_task_detach(&prunetask);
-	}
 
 	cache->filename = NULL;
 
@@ -327,6 +347,9 @@ cleanup_filelock:
 	if (cache->name != NULL) {
 		isc_mem_free(cmctx, cache->name);
 	}
+	if (cache->taskmgr != NULL) {
+		isc_taskmgr_detach(&cache->taskmgr);
+	}
 	isc_mem_detach(&cache->hmctx);
 	isc_mem_putanddetach(&cache->mctx, cache, sizeof(*cache));
 	return (result);
@@ -398,6 +421,10 @@ cache_free(dns_cache_t *cache) {
 		isc_stats_detach(&cache->stats);
 	}
 
+	if (cache->taskmgr != NULL) {
+		isc_taskmgr_detach(&cache->taskmgr);
+	}
+
 	isc_mutex_destroy(&cache->lock);
 	isc_mutex_destroy(&cache->filelock);
 
diff --git a/lib/dns/include/dns/cache.h b/lib/dns/include/dns/cache.h
index b840a543ac..02dd1ac4d0 100644
--- a/lib/dns/include/dns/cache.h
+++ b/lib/dns/include/dns/cache.h
@@ -62,25 +62,20 @@ dns_cache_create(isc_mem_t *cmctx, isc_mem_t *hmctx, isc_taskmgr_t *taskmgr,
 		 const char *cachename, const char *db_type,
 		 unsigned int db_argc, char **db_argv, dns_cache_t **cachep);
 /*%<
- * Create a new DNS cache.
- *
- * dns_cache_create2() will create a named cache.
- *
- * dns_cache_create3() will create a named cache using two separate memory
- * contexts, one for cache data which can be cleaned and a separate one for
- * memory allocated for the heap (which can grow without an upper limit and
- * has no mechanism for shrinking).
- *
- * dns_cache_create() is a backward compatible version that internally
- * specifies an empty cache name and a single memory context.
+ * Create a new named DNS cache using two separate memory contexts, one for
+ * cache data which can be cleaned and a separate one for memory allocated for
+ * the heap (which can grow without an upper limit and has no mechanism for
+ * shrinking).
  *
  * Requires:
  *
- *\li	'cmctx' (and 'hmctx' if applicable) is a valid memory context.
+ *\li	'cmctx' and 'hmctx' are valid memory contexts.
+ *
+ *\li	'taskmgr' is a valid task manager (if 'db_type' is "rbt").
  *
  *\li	'taskmgr' is a valid task manager and 'timermgr' is a valid timer
- * 	manager, or both are NULL.  If NULL, no periodic cleaning of the
- * 	cache will take place.
+ * 	manager, or both are NULL (if 'db_type' is not "rbt").  If NULL, no
+ * 	periodic cleaning of the cache will take place.
  *
  *\li	'cachename' is a valid string.  This must not be NULL.
  *