question: static void externalHelpJoin ( ForkJoinTask < ? > t ) { ForkJoinPool p ; WorkQueue [ ] ws ; WorkQueue q , w ; Submitter z ; ForkJoinTask < ? > [ ] a ; int m , s , n ; if ( t != null && ( z = submitters . get ( ) ) != null && ( p = commonPool ) != null && ( ws = p . workQueues ) != null && ( m = ws . length - 1 ) >= 0 && ( q = ws [ m & z . seed & SQMASK ] ) != null && ( a = q . array ) != null ) { int am = a . length - 1 ; if ( ( s = q . top ) != q . base ) { long j = ( ( am & ( s - 1 ) ) << ASHIFT ) + ABASE ; if ( U . getObject ( a , j ) == t && U . compareAndSwapInt ( q , QLOCK , 0 , 1 ) ) { if ( q . array == a && q . top == s && U . compareAndSwapObject ( a , j , t , null ) ) { q . top = s - 1 ; q . qlock = 0 ; t . doExec ( ) ; } else q . qlock = 0 ; } } if ( t . status >= 0 ) { if ( t instanceof CountedCompleter ) p . externalHelpComplete ( q , t ) ; else p . helpSignal ( t , q . poolIndex ) ; } } }
target:  Tries to help execute or signal availability of the given task from submitter's queue in common pool.