A Two-list method for synchronization of event driven simulation

The traditional mechanism for maintaining a list of pending events in a discrete event simulation is the simple linked list. However, in large scale simulations this list often becomes cumbersome to maintain since the number of pending events may become quite large. As a result, the execution time required by the simple linked list is often a significant portion of total simulation time. Several articles have been published suggesting improved synchronization procedures. The most efficient procedures reported are the time indexed procedure and the two level procedure. Both methodologies are designed for use in languages such as PASCAL or Pl/l, and as a result neither algorithm translates well into FORTRAN. Further, both procedures require external parameter definition, which is a major handicap to their adoption by a general purpose language. This paper introduces a new synchronization procedure, the two list procedure, which is much faster than simple linked lists for large pending event files. This procedure was designed for implementation in FORTRAN, and properly implemented it is transparent to the user; thus it is ideal for adoption by general purpose simulation languages.