question: private void gc ( ) throws Exception { Runtime rt = Runtime . getRuntime ( ) ; long freeMem0 = rt . freeMemory ( ) ; long freeMem = Long . MAX_VALUE ; int cnt = 0 ; while ( freeMem0 < freeMem && cnt < GC_CALL_CNT ) { System . gc ( ) ; U . sleep ( WAIT_TIME ) ; cnt ++ ; freeMem = freeMem0 ; freeMem0 = rt . freeMemory ( ) ; } }
target:  Calls garbage collector and wait.