Using Executors / newSingleThreadExecutor
Peter
I am investigating using threads using Executors/Callable instead of
the Runnable implementation i normally use.
To simplify my problem i created some code which is shown below.
My expectation was that immediately after submitting a thread using
the submit method, the method returned to the main thread (and
printing "Thread submitted"). Now the output is ;
Thread submitting
Entered thread
java.lang.Exception: Got tired waiting
at theater.CallableTest$MyThread.<init>(CallableTest.java:27)
at theater.CallableTest.startThread(CallableTest.java:46)
at theater.CallableTest.main(CallableTest.java:69)
This implies that MyThread is not started as a new thread but is
called as a method in the main thread.
I probably make a beginners error, but am currently currently unaware
of which ...
Who an help me out ?
Cheers,
Peter
<CODE>
import java.util.concurrent.Callable;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import theater.Theater.SchrijfTheater;
public class CallableTest {
public class MyThread implements Callable<Boolean> {
Boolean status = false ;
MyThread() throws Exception {
System.out.println("Entered thread") ;
Thread.sleep(5000) ;
throw new Exception("Got tired waiting") ;
}
public Boolean call() throws Exception {
return this.status ;
}
}
public void startThread() {
Future<Boolean> results = null ;
ExecutorService execSvc = Executors.newSingleThreadExecutor();
try {
System.out.println("Thread submitting") ;
results = execSvc.submit(new MyThread());
System.out.println("Thread submitted") ;
results.get(3000,TimeUnit.SECONDS) ;
System.out.println("results!") ;
} catch (CancellationException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (TimeoutException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
CallableTest t = new CallableTest() ;
t.startThread() ;
}
}
</CODE>
Daniel Pitts
> Hi,
>
> I am investigating using threads using Executors/Callable instead of
> the Runnable implementation i normally use.
> To simplify my problem i created some code which is shown below.
> My expectation was that immediately after submitting a thread using
> the submit method, the method returned to the main thread (and
> printing "Thread submitted"). Now the output is ;
>
> Thread submitting
> Entered thread
> java.lang.Exception: Got tired waiting
> at theater.CallableTest$MyThread.<init>(CallableTest.java:27)
> at theater.CallableTest.startThread(CallableTest.java:46)
> at theater.CallableTest.main(CallableTest.java:69)
>
> This implies that MyThread is not started as a new thread but is
> called as a method in the main thread.
> I probably make a beginners error, but am currently currently unaware
> of which ...
You are doing all of your work in the constructor of MyThread (which
should be called MyCallable BTW). You should do the work inside your
call() method instead.
Hopefully that helps.
--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>
Peter
Hi Daniel,
That helped !
(And yes, you are right concerning the name of the MyThread class. It
is not logical calling a callable class a thread and can confuse the
reader.)