Multi Thread/processor maze solution

Question

Hi,
I'm working on a assignment to find the shortest solution to a given maze (it has an entrance, exit and walls) using the flooding algorithm (part of the assignment).
Thats fairly straight forward - so no issues there, the problem that I have is that we're told to run the 'same function' on 8 threads and I'm not sure how do gain any sort of effeciency from doing so. What i've done so far is create 8 threads of the below class and simply run each thread - passing each of them the same graph (maze).
class Theflooder implements Runnable{
MyGraph thegraph;
Theflooder(MyGraph a){
thegraph =a;
public void run(){
int last,temp;
last =thegraph.flood();
for(int i =0; ;i++){
temp=thegraph.flood();
if (last == temp) {
break;
last = temp;
the flood() method just carries out the 'flooding' and returns the value of the exit cell, hence the solution is reached when the exit cell value remains the same.
My question is, how could I best split the problem over 8 (and later on, several) threads/processors (using mpijava) bearing in mind some sort of effeciency gain.

Answer 1

I've sorta managed to split up the maze into sections
with each thread working on its own part. The problem
now is what is the terminating condition.Nah, that's a mess; a solution may run through several sections and
you have to figure out the pieces of that puzzle again. Better let all
threads run through the entire maze (or copies thereof) all with a
different strategy (see my reply #1). A 'master' thread registers the
solutions and keeps the shortest one.
Also is there a way in java to get the parent process
to wait for all the child processes to finish?Yep, synchronize on the number of running threads:// somewhere in an object of some class:
int nofRunningThreads;
public void synchronized waitForThem(int n) {
   nofRunningThreads= n;
   try {
      while (nofRunningThreads != 0) wait();
   catch (InterruptedException ie) { ie.printStackTrace(); }
// when a thread finishes it calls this one:
public synchronized void ready() {
   nofRunningThreads--;
   notifyAll();
}kind regards,
Jos