AutoRest : Main thread does not terminate.

[m-moris]

I have tried 1.0 beta.
When I use an asynchronous method, main thread does not terminate.
It looks like OkHttp threads are still remain.

Does anyone know any solution?

package sample.autorest;

import java.io.IOException;

import com.microsoft.azure.CloudException;
import com.microsoft.azure.credentials.ApplicationTokenCredentials;
import com.microsoft.azure.management.compute.ComputeManagementClient;
import com.microsoft.azure.management.compute.ComputeManagementClientImpl;
import com.microsoft.azure.management.compute.models.VirtualMachine;
import com.microsoft.rest.ServiceCall;
import com.microsoft.rest.ServiceCallback;
import com.microsoft.rest.ServiceResponse;

import okhttp3.logging.HttpLoggingInterceptor;

public class App3 {

    public static void main(String[] args) throws CloudException, IllegalArgumentException, IOException, InterruptedException {

        String subscriptionId = "<<your subscription id>>";
        String tenantId = "<<your tenant id>>";
        String clientId = "<<your client id>>";
        String clientKey = "<<your client key>>";

        ApplicationTokenCredentials credentials = new ApplicationTokenCredentials(
                clientId, tenantId, clientKey, null);

        ComputeManagementClient client = new ComputeManagementClientImpl(credentials);
        client.setSubscriptionId(subscriptionId);
        client.setLogLevel(HttpLoggingInterceptor.Level.BODY);

        String rg = "your resource-group-name";
        String rs = "your vm name";

        ServiceCallback<VirtualMachine> serviceCallback = new ServiceCallback<VirtualMachine>() {
            @Override
            public void failure(Throwable t) {
                System.err.println("failed");
            }

            @Override
            public void success(ServiceResponse<VirtualMachine> result) {
                VirtualMachine vm = result.getBody();
                System.out.println(vm.getId());
            }
        };
        ServiceCall async = client.getVirtualMachinesOperations().getAsync(rg, rs, "instanceview", serviceCallback);
        System.out.println("done");
    }
}

[jianghaolu]

Hi @m-moris

This is reproduced and 2 issues are involved here:

1. a bug fixed in Azure/azure-sdk-for-java#622: Shutdown ADAL auth executors autorest#908 that ADAL auth executor was not shutdown.
2. Retrofit uses a non-daemon thread for calling callbacks, which JVM will wait until it finishes. Otherwise JVM might terminate before the success() callback is called. But there is a timeout - so if you wait for ~ 1 min JVM would shut down.
   To eliminate this 1 min, supposedly you need to create daemon threads and manage on your own. But when I gave it a try looks like it's not working.

[jianghaolu]

@normalian

[jianghaolu]

Found a solution:

Create your own executor service with daemon threads:

final ExecutorService executor = Executors.newCachedThreadPool(new ThreadFactory() {
    public Thread newThread(Runnable r) {
        Thread thread = new Thread(r);
        thread.setDaemon(true);
        return thread;
    }
});

and register it in OkHttpClient buider:

final OkHttpClient client = new OkHttpClient.Builder().dispatcher(new Dispatcher(executor)).build();

and pass that into ComputeManagementClientImpl's constructor.

By doing so your JVM will exit before your callbacks are called, so create a CountDownLatch of value 1 and count it down in your callbacks. call await() before main() terminates.

final CountDownLatch latch = new CountDownLatch(1);
ServiceCallback<VirtualMachine> serviceCallback = new ServiceCallback<VirtualMachine>() {
    @Override
    public void failure(Throwable t) {
        System.err.println("failed");
        latch.countDown();
    }
   @Override
    public void success(ServiceResponse<VirtualMachine> result) {
        VirtualMachine vm = result.getBody();
        System.out.println(vm.getId());
        latch.countDown();
    }
};
ServiceCall async = client.getVirtualMachinesOperations().getAsync(rg, rs, "instanceview", serviceCallback);
System.out.println("done");
latch.await();

[m-moris]

Hi @jianghaolu @normalian

Thank you for your help.

I executed my sample programs and it looks like working properly. I think it is a little bit troublesome to use CountDownLatch class. I continue to try and investigate the easiest way to async method.

Thanks.

[jianghaolu]

@m-moris
There is really no reconciliation in this. You either run it in a daemon thread and wait with something like CountDownLatch (otherwise JVM will exit before callback is called), or run it in a non-daemon thread, then JVM will wait with a timeout.

[jianghaolu]

@m-moris
But if you find something better than CountDownLatch, please let us know. I would like to know that too :) Or feel free to open a pull request with a sample. :)