[GitHub] [flink] zentol commented on a change in pull request #13424: [FLINK-19219] Run JobManager initialization in separate thread to make it cancellable

[GitBox <gi...@apache.org>]

zentol commented on a change in pull request #13424:
URL: https://github.com/apache/flink/pull/13424#discussion_r492527287



##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/dispatcher/DispatcherJob.java
##########
@@ -119,11 +119,17 @@ private DispatcherJob(
 						}
 					});
 				} else { // failure during initialization
-					final Throwable strippedThrowable = ExceptionUtils.stripCompletionException(throwable);
+					JobStatus finalStatus = JobStatus.FAILED;
+					Throwable strippedThrowable = ExceptionUtils.stripCompletionException(throwable);
+					if (throwable instanceof JobInitializationCancelledException) {

Review comment:
       We could just query the job manager runner for whether it was canceled or not; relying on exception types is quite indirect and can be easily broken by accident.

##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/dispatcher/InitializingJobManagerRunner.java
##########
@@ -0,0 +1,105 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.dispatcher;
+
+import org.apache.flink.api.common.JobID;
+import org.apache.flink.runtime.client.JobInitializationException;
+import org.apache.flink.runtime.concurrent.FutureUtils;
+import org.apache.flink.runtime.jobmaster.JobManagerRunner;
+import org.apache.flink.runtime.messages.Acknowledge;
+import org.apache.flink.runtime.rpc.RpcUtils;
+import org.apache.flink.util.function.SupplierWithException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.annotation.concurrent.GuardedBy;
+
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Wrapper for an initializing JobManagerRunner.
+ */
+public class InitializingJobManagerRunner {
+	private final Logger log = LoggerFactory.getLogger(InitializingJobManagerRunner.class);

Review comment:
       should be static

##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/dispatcher/DispatcherJob.java
##########
@@ -165,17 +171,10 @@ private DispatcherJob(
 			if (isInitialized()) {
 				return getJobMasterGateway().thenCompose(jobMasterGateway -> jobMasterGateway.cancel(timeout));
 			} else {
-				log.info("Cancellation during initialization requested for job {}. Job will be cancelled once JobManager has been initialized.", jobId);
+				log.info("Cancellation during initialization for job {}.", jobId);

Review comment:
       Is the fact that it is still initializing relevant enough for users to mention it in an info message?

##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/dispatcher/InitializingJobManagerRunner.java
##########
@@ -0,0 +1,105 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.dispatcher;
+
+import org.apache.flink.api.common.JobID;
+import org.apache.flink.runtime.client.JobInitializationException;
+import org.apache.flink.runtime.concurrent.FutureUtils;
+import org.apache.flink.runtime.jobmaster.JobManagerRunner;
+import org.apache.flink.runtime.messages.Acknowledge;
+import org.apache.flink.runtime.rpc.RpcUtils;
+import org.apache.flink.util.function.SupplierWithException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.annotation.concurrent.GuardedBy;
+
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Wrapper for an initializing JobManagerRunner.
+ */
+public class InitializingJobManagerRunner {
+	private final Logger log = LoggerFactory.getLogger(InitializingJobManagerRunner.class);
+
+	private final CompletableFuture<JobManagerRunner> jobManagerRunnerFuture = new CompletableFuture<>();
+
+	private final Thread initializationRunner;
+
+	private final Object lock = new Object();
+
+	@GuardedBy("lock")
+	private CompletableFuture<Acknowledge> cancellationFuture;
+
+	public InitializingJobManagerRunner(SupplierWithException<JobManagerRunner, JobInitializationException> initializationRunnable, JobID jobID) {
+		String threadName = "jobmanager-initialization-" + jobID;

Review comment:
       ```suggestion
   		String threadName = "flink-jobmanager-initialization-" + jobID;
   ```
   It would be good if all threads that we create have a "flink" prefix, just so we can see at a glance where it comes from.

##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/dispatcher/InitializingJobManagerRunner.java
##########
@@ -0,0 +1,105 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.dispatcher;
+
+import org.apache.flink.api.common.JobID;
+import org.apache.flink.runtime.client.JobInitializationException;
+import org.apache.flink.runtime.concurrent.FutureUtils;
+import org.apache.flink.runtime.jobmaster.JobManagerRunner;
+import org.apache.flink.runtime.messages.Acknowledge;
+import org.apache.flink.runtime.rpc.RpcUtils;
+import org.apache.flink.util.function.SupplierWithException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.annotation.concurrent.GuardedBy;
+
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Wrapper for an initializing JobManagerRunner.
+ */
+public class InitializingJobManagerRunner {
+	private final Logger log = LoggerFactory.getLogger(InitializingJobManagerRunner.class);
+
+	private final CompletableFuture<JobManagerRunner> jobManagerRunnerFuture = new CompletableFuture<>();
+
+	private final Thread initializationRunner;
+
+	private final Object lock = new Object();
+
+	@GuardedBy("lock")
+	private CompletableFuture<Acknowledge> cancellationFuture;
+
+	public InitializingJobManagerRunner(SupplierWithException<JobManagerRunner, JobInitializationException> initializationRunnable, JobID jobID) {
+		String threadName = "jobmanager-initialization-" + jobID;
+		this.initializationRunner = new Thread(() -> {
+			log.debug("Starting JobManager initialization thread: {}", threadName);
+			try {
+				runInitialization(initializationRunnable);
+			} catch (Throwable threadError) {
+				log.warn("Unexpected error in thread '{}'", threadName, threadError);
+			} finally {
+				log.debug("Stopping JobManager initialization thread: {}", threadName);
+			}
+		}, threadName);
+		this.initializationRunner.setDaemon(true); // this should not block the JVM from shutting down
+		this.initializationRunner.start();
+	}
+
+	private void runInitialization(SupplierWithException<JobManagerRunner, JobInitializationException> initializationRunnable) {
+		try {
+			JobManagerRunner runner = initializationRunnable.get();
+			synchronized (lock) {
+				if (cancellationFuture == null) {
+					jobManagerRunnerFuture.complete(runner);
+				} else {
+					// jobMaster has finished despite the interruption. Cancel job.
+					FutureUtils.forward(runner.getJobMasterGateway().thenCompose(gateway -> gateway.cancel(RpcUtils.INF_TIMEOUT)),
+						cancellationFuture);
+					jobManagerRunnerFuture.complete(runner);
+				}
+			}
+		} catch (JobInitializationException throwable) {
+			synchronized (lock) {
+				if (cancellationFuture == null) {
+					jobManagerRunnerFuture.completeExceptionally(throwable);
+				} else {
+					// an exception related to an interruption is expected here.
+					log.debug("Cancellation finished with (expected) exception", throwable);
+					jobManagerRunnerFuture.completeExceptionally(new JobInitializationCancelledException("Job initialization has been cancelled", throwable));
+					cancellationFuture.complete(Acknowledge.get());
+				}
+			}
+		}
+	}
+
+	public CompletableFuture<Acknowledge> cancelInitialization() {
+		synchronized (lock) {
+			initializationRunner.interrupt();

Review comment:
       So...this only has any effect if the initializing thread is stuck in a blocking operation. What cases are we targeting here?

##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/dispatcher/InitializingJobManagerRunner.java
##########
@@ -0,0 +1,105 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.dispatcher;
+
+import org.apache.flink.api.common.JobID;
+import org.apache.flink.runtime.client.JobInitializationException;
+import org.apache.flink.runtime.concurrent.FutureUtils;
+import org.apache.flink.runtime.jobmaster.JobManagerRunner;
+import org.apache.flink.runtime.messages.Acknowledge;
+import org.apache.flink.runtime.rpc.RpcUtils;
+import org.apache.flink.util.function.SupplierWithException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.annotation.concurrent.GuardedBy;
+
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Wrapper for an initializing JobManagerRunner.
+ */
+public class InitializingJobManagerRunner {
+	private final Logger log = LoggerFactory.getLogger(InitializingJobManagerRunner.class);
+
+	private final CompletableFuture<JobManagerRunner> jobManagerRunnerFuture = new CompletableFuture<>();
+
+	private final Thread initializationRunner;
+
+	private final Object lock = new Object();
+
+	@GuardedBy("lock")
+	private CompletableFuture<Acknowledge> cancellationFuture;
+
+	public InitializingJobManagerRunner(SupplierWithException<JobManagerRunner, JobInitializationException> initializationRunnable, JobID jobID) {
+		String threadName = "jobmanager-initialization-" + jobID;
+		this.initializationRunner = new Thread(() -> {

Review comment:
       Why isn't this using a thread pool?




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