[Shootout-list] process creation & message passing
Isaac Gouy
igouy2@yahoo.com
Sat, 16 Oct 2004 14:48:20 -0700 (PDT)
chainmsg
- create 3000 *linked* processes/threads/...
- send message 0 from one end of the chain
- each process/thread/... receives an integer x, stores x,
and passes x+1 to the next process/thread/... in the chain
: print the final sum (which should be 3000 * messages)
(1 parameter: how many messages are sent)
Timing within a Java 'chainmsg' program, gave
java chainmsg 200 - 11.266s
java chainmsg 400 - 20.219s
java chainmsg 600 - 29.218s
java chainmsg 800 - 38.688s
java chainmsg 1000 - 47.407s
That final test made 3,000,000 transfers.
public class chainmsg {
static final int LENGTH = 3000;
public static void main(String args[]) {
int m = 1;
if (args.length > 0) m = Integer.parseInt(args[0]);
EndLink chainEnd = new EndLink(null, LENGTH * m);
chainEnd.start();
Link chain = chainEnd;
for (int i=2; i<=LENGTH; i++){
Link link = new Link(chain);
link.start();
chain = link;
}
for (int i=0; i<m; i++) chain.put(0);
try { chainEnd.join(); } catch (InterruptedException e){}
System.out.println(chainEnd.checksum);
System.exit(0);
}
}
class Link extends Thread {
Link next;
int message = -1;
boolean busy = false;
Link(Link t){
next = t;
}
public void run() {
for (;;) next.put(this.take());
}
synchronized void put(int m) {
while (busy)
try { wait(); } catch (InterruptedException e){}
busy = true;
message = m;
notifyAll();
while (message != -1)
try { wait(); } catch (InterruptedException e){}
busy = false;
notifyAll();
}
synchronized int take() {
while (message == -1)
try { wait(); } catch (InterruptedException e){}
int m = message;
message = -1;
notifyAll();
return m+1;
}
}
class EndLink extends Link {
public long checksum = 0;
private long finalsum;
EndLink(Link t, int i){
super(t);
finalsum = i;
}
public void run() {
do
checksum += this.take();
while (checksum < finalsum);
}
}
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