/*
* 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.util;
import org.apache.flink.core.testutils.CommonTestUtils;
import org.apache.flink.runtime.testutils.TestJvmProcess;
import org.apache.flink.util.OperatingSystem;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.File;
import java.util.UUID;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import static org.junit.Assume.assumeTrue;
/**
* Test that verifies the behavior of blocking shutdown hooks and of the
* {@link JvmShutdownSafeguard} that guards against it.
*/
public class BlockingShutdownTest {
@Test
public void testProcessShutdownBlocking() throws Exception {
// this test works only on linux
assumeTrue(OperatingSystem.isLinux());
// this test leaves remaining processes if not executed with Java 8
CommonTestUtils.assumeJava8();
final File markerFile = new File(
EnvironmentInformation.getTemporaryFileDirectory(), UUID.randomUUID() + ".marker");
final BlockingShutdownProcess blockingProcess =
new BlockingShutdownProcess(markerFile.getAbsolutePath(), 0, false);
try {
blockingProcess.startProcess();
long pid = blockingProcess.getProcessId();
assertTrue("Cannot determine process ID", pid != -1);
// wait for the marker file to appear, which means the process is up properly
TestJvmProcess.waitForMarkerFile(markerFile, 30000);
// send it a regular kill command (SIG_TERM)
Process kill = Runtime.getRuntime().exec("kill " + pid);
kill.waitFor();
assertEquals("failed to send SIG_TERM to process", 0, kill.exitValue());
// minimal delay until the Java process object notices that the process is gone
// this will not let the test fail predictably if the process is actually in fact going away,
// but it would create frequent failures. Not ideal, but the best we can do without
// severely prolonging the test
Thread.sleep(50);
// the process should not go away by itself
assertTrue("Test broken, process shutdown blocking does not work", blockingProcess.isAlive());
}
finally {
blockingProcess.destroy();
//noinspection ResultOfMethodCallIgnored
markerFile.delete();
}
}
@Test
public void testProcessExitsDespiteBlockingShutdownHook() throws Exception {
// this test works only on linux
assumeTrue(OperatingSystem.isLinux());
final File markerFile = new File(
EnvironmentInformation.getTemporaryFileDirectory(), UUID.randomUUID() + ".marker");
final BlockingShutdownProcess blockingProcess =
new BlockingShutdownProcess(markerFile.getAbsolutePath(), 100, true);
try {
blockingProcess.startProcess();
long pid = blockingProcess.getProcessId();
assertTrue("Cannot determine process ID", pid != -1);
// wait for the marker file to appear, which means the process is up properly
TestJvmProcess.waitForMarkerFile(markerFile, 30000);
// send it a regular kill command (SIG_TERM)
Process kill = Runtime.getRuntime().exec("kill " + pid);
kill.waitFor();
assertEquals("failed to send SIG_TERM to process", 0, kill.exitValue());
// the process should eventually go away
final long deadline = System.nanoTime() + 30_000_000_000L; // 30 secs in nanos
while (blockingProcess.isAlive() && System.nanoTime() < deadline) {
Thread.sleep(50);
}
assertFalse("shutdown blocking process does not properly terminate itself", blockingProcess.isAlive());
}
finally {
blockingProcess.destroy();
//noinspection ResultOfMethodCallIgnored
markerFile.delete();
}
}
// ------------------------------------------------------------------------
// Utilities
// ------------------------------------------------------------------------
// a method that blocks indefinitely
static void parkForever() {
// park this forever
final Object lock = new Object();
//noinspection InfiniteLoopStatement
while (true) {
try {
//noinspection SynchronizationOnLocalVariableOrMethodParameter
synchronized (lock) {
lock.wait();
}
} catch (InterruptedException ignored) {}
}
}
// ------------------------------------------------------------------------
// Blocking Process Implementation
// ------------------------------------------------------------------------
private static final class BlockingShutdownProcess extends TestJvmProcess {
private final String tempFilePath;
private final long selfKillDelay;
private final boolean installSignalHandler;
public BlockingShutdownProcess(String tempFilePath, long selfKillDelay, boolean installSignalHandler)
throws Exception {
this.tempFilePath = tempFilePath;
this.selfKillDelay = selfKillDelay;
this.installSignalHandler = installSignalHandler;
}
@Override
public String getName() {
return "BlockingShutdownProcess";
}
@Override
public String[] getJvmArgs() {
return new String[] { tempFilePath, String.valueOf(installSignalHandler), String.valueOf(selfKillDelay) };
}
@Override
public String getEntryPointClassName() {
return BlockingShutdownProcessEntryPoint.class.getName();
}
}
// ------------------------------------------------------------------------
public static final class BlockingShutdownProcessEntryPoint {
private static final Logger LOG = LoggerFactory.getLogger(BlockingShutdownProcessEntryPoint.class);
public static void main(String[] args) throws Exception {
File touchFile = new File(args[0]);
boolean installHandler = Boolean.parseBoolean(args[1]);
long killDelay = Long.parseLong(args[2]);
// install the blocking shutdown hook
Thread shutdownHook = new Thread(new BlockingRunnable(), "Blocking ShutdownHook");
try {
// Add JVM shutdown hook to call shutdown of service
Runtime.getRuntime().addShutdownHook(shutdownHook);
}
catch (IllegalStateException ignored) {
// JVM is already shutting down. No need to do this.
}
catch (Throwable t) {
System.err.println("Cannot register process cleanup shutdown hook.");
t.printStackTrace();
}
// install the jvm terminator, if we want it
if (installHandler) {
JvmShutdownSafeguard.installAsShutdownHook(LOG, killDelay);
}
System.err.println("signaling process started");
TestJvmProcess.touchFile(touchFile);
System.err.println("parking the main thread");
parkForever();
}
}
// ------------------------------------------------------------------------
static final class BlockingRunnable implements Runnable {
@Override
public void run() {
System.err.println("starting shutdown hook");
parkForever();
}
}
}