Each executor will, during its initialization, invoke this method on each + * plugin provided in the spark.executor.plugins configuration.
+ * + *Plugins should create threads in their implementation of this method for + * any polling, blocking, or intensive computation.
+ */ + default void init() {} + + /** + * Clean up and terminate this plugin. + * + *This function is called during the executor shutdown phase. The executor + * will wait for the plugin to terminate before continuing its own shutdown.
+ */ + default void shutdown() {} +} diff --git a/core/src/main/scala/org/apache/spark/executor/Executor.scala b/core/src/main/scala/org/apache/spark/executor/Executor.scala index b1856ff0f3247..e7dd07b875652 100644 --- a/core/src/main/scala/org/apache/spark/executor/Executor.scala +++ b/core/src/main/scala/org/apache/spark/executor/Executor.scala @@ -136,6 +136,29 @@ private[spark] class Executor( // for fetching remote cached RDD blocks, so need to make sure it uses the right classloader too. env.serializerManager.setDefaultClassLoader(replClassLoader) + private val executorPlugins: Seq[ExecutorPlugin] = { + val pluginNames = conf.get(EXECUTOR_PLUGINS) + if (pluginNames.nonEmpty) { + logDebug(s"Initializing the following plugins: ${pluginNames.mkString(", ")}") + + // Plugins need to load using a class loader that includes the executor's user classpath + val pluginList: Seq[ExecutorPlugin] = + Utils.withContextClassLoader(replClassLoader) { + val plugins = Utils.loadExtensions(classOf[ExecutorPlugin], pluginNames, conf) + plugins.foreach { plugin => + plugin.init() + logDebug(s"Successfully loaded plugin " + plugin.getClass().getCanonicalName()) + } + plugins + } + + logDebug("Finished initializing plugins") + pluginList + } else { + Nil + } + } + // Max size of direct result. If task result is bigger than this, we use the block manager // to send the result back. private val maxDirectResultSize = Math.min( @@ -219,6 +242,18 @@ private[spark] class Executor( heartbeater.shutdown() heartbeater.awaitTermination(10, TimeUnit.SECONDS) threadPool.shutdown() + + // Notify plugins that executor is shutting down so they can terminate cleanly + Utils.withContextClassLoader(replClassLoader) { + executorPlugins.foreach { plugin => + try { + plugin.shutdown() + } catch { + case e: Exception => + logWarning("Plugin " + plugin.getClass().getCanonicalName() + " shutdown failed", e) + } + } + } if (!isLocal) { env.stop() } diff --git a/core/src/main/scala/org/apache/spark/internal/config/package.scala b/core/src/main/scala/org/apache/spark/internal/config/package.scala index a8aa6914ffdae..abdeaf909db08 100644 --- a/core/src/main/scala/org/apache/spark/internal/config/package.scala +++ b/core/src/main/scala/org/apache/spark/internal/config/package.scala @@ -604,4 +604,14 @@ package object config { .intConf .checkValue(v => v > 0, "The max failures should be a positive value.") .createWithDefault(40) + + private[spark] val EXECUTOR_PLUGINS = + ConfigBuilder("spark.executor.plugins") + .doc("Comma-separated list of class names for \"plugins\" implementing " + + "org.apache.spark.ExecutorPlugin. Plugins have the same privileges as any task " + + "in a Spark executor. They can also interfere with task execution and fail in " + + "unexpected ways. So be sure to only use this for trusted plugins.") + .stringConf + .toSequence + .createWithDefault(Nil) } diff --git a/core/src/main/scala/org/apache/spark/util/Utils.scala b/core/src/main/scala/org/apache/spark/util/Utils.scala index 7ec707d94ed87..f6062d2732f98 100644 --- a/core/src/main/scala/org/apache/spark/util/Utils.scala +++ b/core/src/main/scala/org/apache/spark/util/Utils.scala @@ -240,6 +240,19 @@ private[spark] object Utils extends Logging { // scalastyle:on classforname } + /** + * Run a segment of code using a different context class loader in the current thread + */ + def withContextClassLoader[T](ctxClassLoader: ClassLoader)(fn: => T): T = { + val oldClassLoader = Thread.currentThread().getContextClassLoader() + try { + Thread.currentThread().setContextClassLoader(ctxClassLoader) + fn + } finally { + Thread.currentThread().setContextClassLoader(oldClassLoader) + } + } + /** * Primitive often used when writing [[java.nio.ByteBuffer]] to [[java.io.DataOutput]] */ diff --git a/core/src/test/java/org/apache/spark/ExecutorPluginSuite.java b/core/src/test/java/org/apache/spark/ExecutorPluginSuite.java new file mode 100644 index 0000000000000..686eb28010c6a --- /dev/null +++ b/core/src/test/java/org/apache/spark/ExecutorPluginSuite.java @@ -0,0 +1,139 @@ +/* + * 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.spark; + +import org.apache.spark.api.java.JavaSparkContext; + +import org.junit.After; +import org.junit.Before; +import org.junit.Test; + +import static org.junit.Assert.*; + +public class ExecutorPluginSuite { + private static final String EXECUTOR_PLUGIN_CONF_NAME = "spark.executor.plugins"; + private static final String testBadPluginName = TestBadShutdownPlugin.class.getName(); + private static final String testPluginName = TestExecutorPlugin.class.getName(); + private static final String testSecondPluginName = TestSecondPlugin.class.getName(); + + // Static value modified by testing plugins to ensure plugins loaded correctly. + public static int numSuccessfulPlugins = 0; + + // Static value modified by testing plugins to verify plugins shut down properly. + public static int numSuccessfulTerminations = 0; + + private JavaSparkContext sc; + + @Before + public void setUp() { + sc = null; + numSuccessfulPlugins = 0; + numSuccessfulTerminations = 0; + } + + @After + public void tearDown() { + if (sc != null) { + sc.stop(); + sc = null; + } + } + + private SparkConf initializeSparkConf(String pluginNames) { + return new SparkConf() + .setMaster("local") + .setAppName("test") + .set(EXECUTOR_PLUGIN_CONF_NAME, pluginNames); + } + + @Test + public void testPluginClassDoesNotExist() { + SparkConf conf = initializeSparkConf("nonexistant.plugin"); + try { + sc = new JavaSparkContext(conf); + fail("No exception thrown for nonexistant plugin"); + } catch (Exception e) { + // We cannot catch ClassNotFoundException directly because Java doesn't think it'll be thrown + assertTrue(e.toString().startsWith("java.lang.ClassNotFoundException")); + } + } + + @Test + public void testAddPlugin() throws InterruptedException { + // Load the sample TestExecutorPlugin, which will change the value of numSuccessfulPlugins + SparkConf conf = initializeSparkConf(testPluginName); + sc = new JavaSparkContext(conf); + assertEquals(1, numSuccessfulPlugins); + sc.stop(); + sc = null; + assertEquals(1, numSuccessfulTerminations); + } + + @Test + public void testAddMultiplePlugins() throws InterruptedException { + // Load two plugins and verify they both execute. + SparkConf conf = initializeSparkConf(testPluginName + "," + testSecondPluginName); + sc = new JavaSparkContext(conf); + assertEquals(2, numSuccessfulPlugins); + sc.stop(); + sc = null; + assertEquals(2, numSuccessfulTerminations); + } + + @Test + public void testPluginShutdownWithException() { + // Verify an exception in one plugin shutdown does not affect the others + String pluginNames = testPluginName + "," + testBadPluginName + "," + testPluginName; + SparkConf conf = initializeSparkConf(pluginNames); + sc = new JavaSparkContext(conf); + assertEquals(3, numSuccessfulPlugins); + sc.stop(); + sc = null; + assertEquals(2, numSuccessfulTerminations); + } + + public static class TestExecutorPlugin implements ExecutorPlugin { + public void init() { + ExecutorPluginSuite.numSuccessfulPlugins++; + } + + public void shutdown() { + ExecutorPluginSuite.numSuccessfulTerminations++; + } + } + + public static class TestSecondPlugin implements ExecutorPlugin { + public void init() { + ExecutorPluginSuite.numSuccessfulPlugins++; + } + + public void shutdown() { + ExecutorPluginSuite.numSuccessfulTerminations++; + } + } + + public static class TestBadShutdownPlugin implements ExecutorPlugin { + public void init() { + ExecutorPluginSuite.numSuccessfulPlugins++; + } + + public void shutdown() { + throw new RuntimeException("This plugin will fail to cleanly shut down"); + } + } +}