$pid = 0; #process index
@p_s = (); #2d process array/stack
%sender = (); #sending event hash
%receiver = (); #receiving event hash
$numevents = 0; #total number of events in all processes 
$timestamp = 0; #timestamp for event scheduler
%schedule = (); #hash of each event with timestamp
@totalorder = (); #final order of each event