6. Nebenläufigkeit

• Shared Memory Computer
  Prozesse, Threads

• Distributed Memory Computer
  Nachrichtenaustausch

• Ausnahmebehandlung und Ereignisse
  Exceptions und Events

6.1 Shared Memory Computer

Java

   public class sema {
   
     private int init;
     private int s;
     private int del;
   
     public sema() {
       this(0);
     }
   
     public sema(int i) {
       if (i >=0) { init = i; } else { init = 0; }
       s = init; del = 0;
     }
   
     protected void finalize() throws Throwable {
       if (init != s) { int x = s - init;
           System.out.println("sema: " + x + 
                              " pending operations."); 
       }
       super.finalize();
     }

     public synchronized void P() {
       while (s <= 0) {
         del++;
         try { 
             this.wait(); 
         } catch (InterruptedException e) {}
         del--;
       }
       s--;
     }
   
     public synchronized void V() {
       s++;
       if (del > 0) { this.notify(); } // Bem *
     }
   }

6.2 Distributed Memory Computer

6.3 Ausnahmebehandlung und Ereignisse