[GitHub] [zeppelin] Reamer commented on a change in pull request #4035: [ZEPPELIN-5225] Remote interpreter soft shutdown

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

Reamer commented on a change in pull request #4035:
URL: https://github.com/apache/zeppelin/pull/4035#discussion_r567662046



##########
File path: zeppelin-zengine/src/main/java/org/apache/zeppelin/interpreter/remote/ExecRemoteInterpreterProcess.java
##########
@@ -0,0 +1,234 @@
+/*
+ * 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.zeppelin.interpreter.remote;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.apache.commons.exec.CommandLine;
+import org.apache.commons.exec.ExecuteException;
+import org.apache.hadoop.yarn.util.ConverterUtils;
+import org.apache.zeppelin.interpreter.YarnAppMonitor;
+import org.apache.zeppelin.interpreter.util.ProcessLauncher;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.annotations.VisibleForTesting;
+
+public class ExecRemoteInterpreterProcess extends RemoteInterpreterManagedProcess {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(ExecRemoteInterpreterProcess.class);
+
+  private static final Pattern YARN_APP_PATTER = Pattern.compile("Submitted application (\\w+)");
+
+  private final String interpreterRunner;
+  private InterpreterProcessLauncher interpreterProcessLauncher;
+
+  public ExecRemoteInterpreterProcess(
+      int intpEventServerPort,
+      String intpEventServerHost,
+      String interpreterPortRange,
+      String intpDir,
+      String localRepoDir,
+      Map<String, String> env,
+      int connectTimeout,
+      int connectionPoolSize,
+      String interpreterSettingName,
+      String interpreterGroupId,
+      boolean isUserImpersonated,
+      String intpRunner) {
+    super(intpEventServerPort, intpEventServerHost, interpreterPortRange, intpDir, localRepoDir, env, connectTimeout,
+        connectionPoolSize, interpreterSettingName, interpreterGroupId, isUserImpersonated);
+    this.interpreterRunner = intpRunner;
+  }
+
+  @Override
+  public void start(String userName) throws IOException {
+    // start server process
+    CommandLine cmdLine = CommandLine.parse(interpreterRunner);
+    cmdLine.addArgument("-d", false);
+    cmdLine.addArgument(getInterpreterDir(), false);
+    cmdLine.addArgument("-c", false);
+    cmdLine.addArgument(getIntpEventServerHost(), false);
+    cmdLine.addArgument("-p", false);
+    cmdLine.addArgument(String.valueOf(intpEventServerPort), false);
+    cmdLine.addArgument("-r", false);
+    cmdLine.addArgument(getInterpreterPortRange(), false);
+    cmdLine.addArgument("-i", false);
+    cmdLine.addArgument(getInterpreterGroupId(), false);
+    if (isUserImpersonated() && !userName.equals("anonymous")) {
+      cmdLine.addArgument("-u", false);
+      cmdLine.addArgument(userName, false);
+    }
+    cmdLine.addArgument("-l", false);
+    cmdLine.addArgument(getLocalRepoDir(), false);
+    cmdLine.addArgument("-g", false);
+    cmdLine.addArgument(getInterpreterSettingName(), false);
+
+    interpreterProcessLauncher = new InterpreterProcessLauncher(cmdLine, getEnv());
+    interpreterProcessLauncher.launch();
+    interpreterProcessLauncher.waitForReady(getConnectTimeout());
+    if (interpreterProcessLauncher.isLaunchTimeout()) {
+      throw new IOException(
+          String.format("Interpreter Process creation is time out in %d seconds", getConnectTimeout() / 1000) + "\n"
+              + "You can increase timeout threshold via "
+              + "setting zeppelin.interpreter.connect.timeout of this interpreter.\n"
+              + interpreterProcessLauncher.getErrorMessage());
+    }
+
+    if (!interpreterProcessLauncher.isRunning()) {
+      throw new IOException("Fail to launch interpreter process:\n" + interpreterProcessLauncher.getErrorMessage());
+    } else {
+      String launchOutput = interpreterProcessLauncher.getProcessLaunchOutput();
+      Matcher m = YARN_APP_PATTER.matcher(launchOutput);
+      if (m.find()) {
+        String appId = m.group(1);
+        LOGGER.info("Detected yarn app: {}, add it to YarnAppMonitor", appId);
+        YarnAppMonitor.get().addYarnApp(ConverterUtils.toApplicationId(appId), this);
+      }
+    }
+  }
+
+  @Override
+  public void processStarted(int port, String host) {
+    super.processStarted(port, host);
+    // for yarn cluster it may be transitioned from COMPLETED to RUNNING.
+    interpreterProcessLauncher.onProcessRunning();
+  }
+
+  @Override
+  public void stop() {
+    if (isRunning()) {
+      super.stop();
+      // wait for a clean shutdown
+      this.interpreterProcessLauncher.waitForShutdown(RemoteInterpreterServer.DEFAULT_SHUTDOWN_TIMEOUT + 500);
+      // kill process
+      this.interpreterProcessLauncher.stop();
+      this.interpreterProcessLauncher = null;
+      LOGGER.info("Remote exec process of interpreter group: {} is terminated", getInterpreterGroupId());
+    } else {
+      LOGGER.warn("Try to stop a not running interpreter process of interpreter group: {}", getInterpreterGroupId());
+    }
+  }
+
+  @VisibleForTesting
+  public String getInterpreterRunner() {
+    return interpreterRunner;
+  }
+
+  @Override
+  public boolean isRunning() {
+    return interpreterProcessLauncher != null && interpreterProcessLauncher.isRunning();
+  }
+
+  @Override
+  public String getErrorMessage() {
+    return this.interpreterProcessLauncher != null
+        ? this.interpreterProcessLauncher.getErrorMessage()
+        : "";
+  }
+
+  private class InterpreterProcessLauncher extends ProcessLauncher {
+
+    public InterpreterProcessLauncher(CommandLine commandLine, Map<String, String> envs) {
+      super(commandLine, envs);
+    }
+
+    public void waitForShutdown(int timeout) {

Review comment:
       The purpose is that Zeppelin server waits for a clean shutdown of the remote interpreter process.
   Application flow:
    - Zeppelin interpreter process must be stopped, reason can be different
      - [code line](https://github.com/apache/zeppelin/pull/4035/files#diff-0f9e2999402c639082389ae5e0f54dbf631ce099f877850d8a7db47346a00000R79) 
    - Zeppelin Server performs a shutdown call, which is a synchronous operation
      -  [```
            callRemoteFunction(client -> {
           client.shutdown();
           return null;
         });```](https://github.com/apache/zeppelin/pull/4035/files#diff-0f9e2999402c639082389ae5e0f54dbf631ce099f877850d8a7db47346a00000R82)
    - The shutdown of the remote interpreter itself is asynchronous, because it's done in a separate shutdown thread
      - [code line](https://github.com/apache/zeppelin/blob/a22b59e18a3ea9e844f7fb288c1c3bb9b0dc94b9/zeppelin-interpreter/src/main/java/org/apache/zeppelin/interpreter/remote/RemoteInterpreterServer.java#L259-L260)
    - Normally, the remote interpreter stops cleanly in only a few milliseconds
    - That the process is stopped is recognised by the `ExecuteResultHandler`, which is implemented by the `ProcessLauncher` and overridden by the `InterpreterProcessLauncher`
   
   If the remote interpreter does not stop in a certain time, the Zeppelin server terminates the process as before this PR with the help of the [Watchdog](https://github.com/apache/zeppelin/blob/a22b59e18a3ea9e844f7fb288c1c3bb9b0dc94b9/zeppelin-interpreter/src/main/java/org/apache/zeppelin/interpreter/util/ProcessLauncher.java#L160-L165).
   




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