question: public static long measureTime ( Callable < Object > c , int threadCnt ) throws Exception { A . ensure ( threadCnt >= 1 , "threadCnt should be >= 1" ) ; long start = System . currentTimeMillis ( ) ; if ( threadCnt == 1 ) c . call ( ) ; else GridTestUtils . runMultiThreaded ( c , threadCnt , "test-worker" ) ; return System . currentTimeMillis ( ) - start ; }
target:  Performs operation, measuring it's time.