[SPARK-12486] Worker should kill the executors more forcefully if pos…

…sible.

This patch updates the ExecutorRunner's terminate path to use the new java 8 API
to terminate processes more forcefully if possible. If the executor is unhealthy,
it would previously ignore the destroy() call. Presumably, the new java API was
added to handle cases like this.

We could update the termination path in the future to use OS specific commands
for older java versions.

Author: Nong Li <nong@databricks.com>

Closes #10438 from nongli/spark-12486-executors.

(cherry picked from commit 8f65939)
Signed-off-by: Andrew Or <andrew@databricks.com>

core/src/main/scala/org/apache/spark/deploy/worker/ExecutorRunner.scala

@@ -23,13 +23,12 @@ import scala.collection.JavaConverters._
 
 import com.google.common.base.Charsets.UTF_8
 import com.google.common.io.Files
-
-import org.apache.spark.rpc.RpcEndpointRef
-import org.apache.spark.{SecurityManager, SparkConf, Logging}
-import org.apache.spark.deploy.{ApplicationDescription, ExecutorState}
 import org.apache.spark.deploy.DeployMessages.ExecutorStateChanged
+import org.apache.spark.deploy.{ApplicationDescription, ExecutorState}
+import org.apache.spark.rpc.RpcEndpointRef
 import org.apache.spark.util.{ShutdownHookManager, Utils}
 import org.apache.spark.util.logging.FileAppender
+import org.apache.spark.{Logging, SecurityManager, SparkConf}
 
 /**
  * Manages the execution of one executor process.
@@ -60,6 +59,9 @@ private[deploy] class ExecutorRunner(
   private var stdoutAppender: FileAppender = null
   private var stderrAppender: FileAppender = null
 
+  // Timeout to wait for when trying to terminate an executor.
+  private val EXECUTOR_TERMINATE_TIMEOUT_MS = 10 * 1000
+
   // NOTE: This is now redundant with the automated shut-down enforced by the Executor. It might
   // make sense to remove this in the future.
   private var shutdownHook: AnyRef = null
@@ -94,8 +96,11 @@ private[deploy] class ExecutorRunner(
       if (stderrAppender != null) {
         stderrAppender.stop()
       }
-      process.destroy()
-      exitCode = Some(process.waitFor())
+      exitCode = Utils.terminateProcess(process, EXECUTOR_TERMINATE_TIMEOUT_MS)
+      if (exitCode.isEmpty) {
+        logWarning("Failed to terminate process: " + process +
+          ". This process will likely be orphaned.")
+      }
     }
     try {
       worker.send(ExecutorStateChanged(appId, execId, state, message, exitCode))

core/src/main/scala/org/apache/spark/util/Utils.scala

@@ -1695,6 +1695,30 @@ private[spark] object Utils extends Logging {
     new File(path).getName
   }
 
+  /**
+   * Terminates a process waiting for at most the specified duration. Returns whether
+   * the process terminated.
+   */
+  def terminateProcess(process: Process, timeoutMs: Long): Option[Int] = {
+    try {
+      // Java8 added a new API which will more forcibly kill the process. Use that if available.
+      val destroyMethod = process.getClass().getMethod("destroyForcibly");
+      destroyMethod.setAccessible(true)
+      destroyMethod.invoke(process)
+    } catch {
+      case NonFatal(e) =>
+        if (!e.isInstanceOf[NoSuchMethodException]) {
+          logWarning("Exception when attempting to kill process", e)
+        }
+        process.destroy()
+    }
+    if (waitForProcess(process, timeoutMs)) {
+      Option(process.exitValue())
+    } else {
+      None
+    }
+  }
+
   /**
    * Wait for a process to terminate for at most the specified duration.
    * Return whether the process actually terminated after the given timeout.

core/src/test/scala/org/apache/spark/util/UtilsSuite.scala

@@ -17,26 +17,24 @@
 
 package org.apache.spark.util
 
-import java.io.{File, ByteArrayOutputStream, ByteArrayInputStream, FileOutputStream}
+import java.io.{ByteArrayInputStream, ByteArrayOutputStream, File, FileOutputStream}
 import java.lang.{Double => JDouble, Float => JFloat}
 import java.net.{BindException, ServerSocket, URI}
 import java.nio.{ByteBuffer, ByteOrder}
 import java.text.DecimalFormatSymbols
-import java.util.concurrent.TimeUnit
 import java.util.Locale
+import java.util.concurrent.TimeUnit
 
 import scala.collection.mutable.ListBuffer
 import scala.util.Random
 
 import com.google.common.base.Charsets.UTF_8
 import com.google.common.io.Files
-
+import org.apache.commons.lang3.SystemUtils
 import org.apache.hadoop.conf.Configuration
 import org.apache.hadoop.fs.Path
-
 import org.apache.spark.network.util.ByteUnit
-import org.apache.spark.{Logging, SparkFunSuite}
-import org.apache.spark.SparkConf
+import org.apache.spark.{Logging, SparkConf, SparkFunSuite}
 
 class UtilsSuite extends SparkFunSuite with ResetSystemProperties with Logging {
 
@@ -745,4 +743,77 @@ class UtilsSuite extends SparkFunSuite with ResetSystemProperties with Logging {
     assert(Utils.decodeFileNameInURI(new URI("files:///abc")) === "abc")
     assert(Utils.decodeFileNameInURI(new URI("files:///abc%20xyz")) === "abc xyz")
   }
+
+  test("Kill process") {
+    // Verify that we can terminate a process even if it is in a bad state. This is only run
+    // on UNIX since it does some OS specific things to verify the correct behavior.
+    if (SystemUtils.IS_OS_UNIX) {
+      def getPid(p: Process): Int = {
+        val f = p.getClass().getDeclaredField("pid")
+        f.setAccessible(true)
+        f.get(p).asInstanceOf[Int]
+      }
+
+      def pidExists(pid: Int): Boolean = {
+        val p = Runtime.getRuntime.exec(s"kill -0 $pid")
+        p.waitFor()
+        p.exitValue() == 0
+      }
+
+      def signal(pid: Int, s: String): Unit = {
+        val p = Runtime.getRuntime.exec(s"kill -$s $pid")
+        p.waitFor()
+      }
+
+      // Start up a process that runs 'sleep 10'. Terminate the process and assert it takes
+      // less time and the process is no longer there.
+      val startTimeMs = System.currentTimeMillis()
+      val process = new ProcessBuilder("sleep", "10").start()
+      val pid = getPid(process)
+      try {
+        assert(pidExists(pid))
+        val terminated = Utils.terminateProcess(process, 5000)
+        assert(terminated.isDefined)
+        Utils.waitForProcess(process, 5000)
+        val durationMs = System.currentTimeMillis() - startTimeMs
+        assert(durationMs < 5000)
+        assert(!pidExists(pid))
+      } finally {
+        // Forcibly kill the test process just in case.
+        signal(pid, "SIGKILL")
+      }
+
+      val v: String = System.getProperty("java.version")
+      if (v >= "1.8.0") {
+        // Java8 added a way to forcibly terminate a process. We'll make sure that works by
+        // creating a very misbehaving process. It ignores SIGTERM and has been SIGSTOPed. On
+        // older versions of java, this will *not* terminate.
+        val file = File.createTempFile("temp-file-name", ".tmp")
+        val cmd =
+          s"""
+             |#!/bin/bash
+             |trap "" SIGTERM
+             |sleep 10
+           """.stripMargin
+        Files.write(cmd.getBytes(), file)
+        file.getAbsoluteFile.setExecutable(true)
+
+        val process = new ProcessBuilder(file.getAbsolutePath).start()
+        val pid = getPid(process)
+        assert(pidExists(pid))
+        try {
+          signal(pid, "SIGSTOP")
+          val start = System.currentTimeMillis()
+          val terminated = Utils.terminateProcess(process, 5000)
+          assert(terminated.isDefined)
+          Utils.waitForProcess(process, 5000)
+          val duration = System.currentTimeMillis() - start
+          assert(duration < 5000)
+          assert(!pidExists(pid))
+        } finally {
+          signal(pid, "SIGKILL")
+        }
+      }
+    }
+  }
 }