question: private WorkQueue findNonEmptyStealQueue ( ) { WorkQueue [ ] ws ; int wl ; int r = TLRandom . nextSecondarySeed ( ) ; if ( ( ws = workQueues ) != null && ( wl = ws . length ) > 0 ) { int m = wl - 1 , origin = r & m ; for ( int k = origin , oldSum = 0 , checkSum = 0 ; ; ) { WorkQueue q ; int b ; if ( ( q = ws [ k ] ) != null ) { if ( ( b = q . base ) - q . top < 0 ) return q ; checkSum += b ; } if ( ( k = ( k + 1 ) & m ) == origin ) { if ( oldSum == ( oldSum = checkSum ) ) break ; checkSum = 0 ; } } } return null ; }
target:  Returns a (probably) non-empty steal queue, if one is found during a scan, else null.  This method must be retried by caller if, by the time it tries to use the queue, it is empty.