java - Running Multiple Thread Pools (ExecutorService) together

Question

I have an object that I need to run through 4 scenarios. I want to split this between 2 threads (so I can send to an additional server) I got this working to the 2 servers, but in trying to clean up the code i have created what looks like this;

 ExecutorService executor1 = Executors.newFixedThreadPool(1);
 ExecutorService executor2 = Executors.newFixedThreadPool(1);

 executor1.execute(userProvisioner1);
 executor1.execute(userProvisioner2);
 executor2.execute(userProvisioner3);
 executor2.execute(userProvisioner4);

 executor1.shutdown();
 executor2.shutdown();

 while (!executor1.isTerminated()&!executor2.isTerminated()) {
 }

userProvisioner1 & userProvisioner2 need to be run sequentially (as do 3 & 4) but can be run along side each other.

This does work, but I have hit issues since trying to use the 2 pools at once. Is this an issue with the pools or something else?

Answer 1

If you need sequential activity, you can call one task and then another. The simple solution in your case is something like this.

ExecutorService exec = Executors.newFixedThreadPool(2);

exec.execute(new Runnable() {
    public void run() {
        userProvisioner1.run();
        userProvisioner2.run();
    }
});
exec.execute(new Runnable() {
    public void run() {
        userProvisioner3.run();
        userProvisioner4.run();
    }
});

exec.shutdown();
exec.awaitTermination();