Fixed tests using dt_start_id().

Doesn't guarantee waking up of the Idle threads
and blocks when used in dt_start().
Caller should either activate existing threads or
use dt_start() instead.

refs #1441

src/knot/server/dthreads.c

@@ -670,7 +670,6 @@ int dt_start_id(dthread_t *thread)
 		dbg_dt("dthreads: [%p] %s: refused to recreate thread\n",
 		         thread, __func__);
 		unlock_thread_rw(thread);
-		dt_activate(thread);
 		return 0;
 	}
 

src/tests/knot/dthreads_tests.c

@@ -159,8 +159,8 @@ static inline int dt_test_resize(dt_unit_t *unit, int size)
 	_runnable_i = 0;
 	for (int i = 0; i < size; ++i) {
 		ret += dt_repurpose(unit->threads[i], &runnable, 0);
-		ret += dt_start_id(unit->threads[i]);
 	}
+	ret += dt_start(unit);
 
 	// Wait for finish
 	ret += dt_join(unit);
@@ -266,7 +266,7 @@ static int dt_tests_run(int argc, char *argv[])
 	pthread_mutex_init(&_runnable_mx, NULL);
 
 	/* Test 1: Create unit */
-	dt_unit_t *unit = dt_test_create(4);
+	dt_unit_t *unit = dt_test_create(2);
 	ok(unit != 0, "dthreads: create unit (optimal size %d)", unit->size);
 	skip(unit == 0, DT_TEST_COUNT - 1);