question: public void shutdown ( ) { while ( true ) { long cur = combinedState . get ( ) ; long newValue = cur | 0x8000000000000000L ; if ( combinedState . compareAndSet ( cur , newValue ) ) { break ; } } }
target:  Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted. Invocation has no additional effect if already shut down.