java - Channel ManagedChannelImpl 未正确关闭

Question

如果我按照这两个测试运行，我会得到错误。

第一次测试

@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);
}

第二次测试

@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)

如果我注释掉其中一个，那么没有错误，单元测试虽然通过，但如果两者一起运行，则会引发异常。

编辑

根据建议。

@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

嘿，我刚刚使用 Dialogflow V2 Java SDK 遇到了类似的问题，我收到了错误

 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.

此外，拥有庞大的客户群，我们开始遇到 out of memory unable to create native thread错误。

在执行了大量的调试操作和使用 Visual VM 线程监控后，我终于发现问题是因为 SessionsClient不关闭。所以我使用附加的代码块来解决这个问题。测试该 block 后，我终于能够释放所有使用的线程，并且前面提到的错误也得到了解决。

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.