Local Thread linked with RequestScope

Question

I have a web service built with VRaptor that uses CDI (weld 2.1.2.Final). I need to parallelize some of the processing made by the server (statistical analysis of industrial alarms). I'm doing that using a ExecutorService and Callable instances, unfortunately I need one Request Scoped dependence inside my Threads. Because of that dependence I'm facing this error:

WELD-001303: No active contexts for scope type javax.enterprise.context.RequestScoped

Is there a way to link the Threads to the Request where they were created using CDI?

*I know that I shouldn't be opening threads in the server, but this is the currently most viable option

What container are you running on? – John Ament Jan 17 '16 at 18:26 — John Ament, Jan 17 '16 at 18:26
I'm running on Tomact 7 – Rafael Teles Jan 17 '16 at 23:34 — Rafael Teles, Jan 17 '16 at 23:34

score 1 · Accepted Answer · edited May 23 '17 at 11:50

1

Pass it as constructor argument of the callable.

public class YourTask implements Callable<String> {

    private YourData data;

    public YourTask(YourData data) {
        this.data = data;
    }

    @Override
    public String call() {
        // Just use data.
    }

}

@Inject
private YourRequestScopedBean bean;

public void submit() {
    YourTask task = new YourTask(bean.getData());
    // ...
}

Note: do not pass the bean itself as it's basically a proxy whose instance doesn't exist in other thread.

Unrelated to the concrete problem, manually managing threads in a Java EE container, even though when done via a properly programmed ExecutorService, is frowned upon. It indicates you aren't aware of possibilities of Java EE's EJB scheduling and timer APIs. You may find the examples in this answer useful: Is it safe to start a new thread in a JSF managed bean?

edited May 23 '17 at 11:50

Community

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answered Jan 17 '16 at 09:26

BalusC

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Thanks for your reply. I know that manually managing threads in a Java EE is frowned upon. But in this case I need (or there is another solution that I can't see), in the system I'm developing we may need to consult 20+ database that may contain millions of data (It's a industrial alarm analysis system), I have to parallelize the process. Maybe I should make a microservice and segrete part of the process from my server, but that solution is too far away and would consume too much time. – Rafael Teles Jan 17 '16 at 23:41
"Note: do not pass the bean itself as it's basically a proxy whose instance doesn't exist in other thread" I didn't know that (I still got a lot to learn), there is no way to pass the bean itself? And once again, thanks for your answer – Rafael Teles Jan 17 '16 at 23:43
I'm also controlling the number of threads one user can spawn, and the total number of threads that can spawn – Rafael Teles Jan 18 '16 at 12:05

Local Thread linked with RequestScope

1 Answers1

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