Channel ManagedChannelImpl was not shut down properly

Question

If I run following these two tests I get the error.

1st test

@Rule
public GrpcCleanupRule grpcCleanup = new GrpcCleanupRule();

@Test
public void findAll() throws Exception {
    // Generate a unique in-process server name.
    String serverName = InProcessServerBuilder.generateName();

    // Create a server, add service, start, and register for automatic graceful shutdown.
    grpcCleanup.register(InProcessServerBuilder
            .forName(serverName)
            .directExecutor()
            .addService(new Data(mockMongoDatabase))
            .build()
            .start());

    // Create a client channel and register for automatic graceful shutdown.
    RoleServiceGrpc.RoleServiceBlockingStub stub = RoleServiceGrpc.newBlockingStub(
            grpcCleanup.register(InProcessChannelBuilder
                    .forName(serverName)
                    .directExecutor()
                    .build()));

    RoleOuter.Response response = stub.findAll(Empty.getDefaultInstance());
    assertNotNull(response);
}

2nd test

@Test
public void testFindAll() {
    ManagedChannel channel = ManagedChannelBuilder.forAddress("localhost", 8081)
            .usePlaintext()
            .build();

    RoleServiceGrpc.RoleServiceBlockingStub stub = RoleServiceGrpc.newBlockingStub(channel);
    RoleOuter.Response response = stub.findAll(Empty.newBuilder().build());
    assertNotNull(response);
}

io.grpc.internal.ManagedChannelOrphanWrapper$ManagedChannelReference cleanQueue SEVERE: ~~~ Channel ManagedChannelImpl{logId=1, target=localhost:8081} was not shutdown properly!!! ~~~ Make sure to call shutdown()/shutdownNow() and wait until awaitTermination() returns true.

java.lang.RuntimeException: ManagedChannel allocation site at io.grpc.internal.ManagedChannelOrphanWrapper$ManagedChannelReference.(ManagedChannelOrphanWrapper.java:94)

If I comment out one of them, then no errors, unit tests pass though but the exception is thrown if both are ran together.

Edit

Based on the suggestion.

@Test
public void testFindAll() {
    ManagedChannel channel = ManagedChannelBuilder.forAddress("localhost", 8081)
            .usePlaintext()
            .build();

    RoleServiceGrpc.RoleServiceBlockingStub stub = RoleServiceGrpc.newBlockingStub(channel);
    RoleOuter.Response response = stub.findAll(Empty.newBuilder().build());
    assertNotNull(response);

    channel.shutdown();
}

Answer 1

Hey I just faced similar issue using Dialogflow V2 Java SDK where I received the error

 Oct 19, 2019 4:12:23 PM io.grpc.internal.ManagedChannelOrphanWrapper$ManagedChannelReference cleanQueue
SEVERE: *~*~*~ Channel ManagedChannelImpl{logId=41, target=dialogflow.googleapis.com:443} was not shutdown properly!!! ~*~*~*
    Make sure to call shutdown()/shutdownNow() and wait until awaitTermination() returns true.

Also, Having a huge customer base we started running into out of memory unable to create native thread error.

After performing a lot of Debugging operations and Using Visual VM Thread Monitoring I finally figured out that the problem was because of SessionsClient not closing. So I used the attached code block to solve that issue. Post testing that block I was finally able to free up all the used threads and also the error mentioned earlier was resolved.

SessionsClient sessionsClient = null;
QueryResult queryResult = null;

try {
    SessionsSettings.Builder settingsBuilder = SessionsSettings.newBuilder();
    SessionsSettings sessionsSettings = settingsBuilder
            .setCredentialsProvider(FixedCredentialsProvider.create(credentials)).build();
    sessionsClient = SessionsClient.create(sessionsSettings);
    SessionName session = SessionName.of(projectId, senderId);
    com.google.cloud.dialogflow.v2.TextInput.Builder textInput = TextInput.newBuilder().setText(message)
            .setLanguageCode(languageCode);
    QueryInput queryInput = QueryInput.newBuilder().setText(textInput).build();

    DetectIntentResponse response = sessionsClient.detectIntent(session, queryInput);

    queryResult = response.getQueryResult();
} catch (Exception e) {
    e.printStackTrace();
}
finally {
    sessionsClient.close();
}

The shorter values on the graph highlights the use of client.close(). Without that the threads were stuck in Parking State.