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Fix [JENKINS-49206] by ensuring Timer threads get standard classloader (

#3272)

* Fix [JENKINS-49206] by ensuring Timer threads get standard classloader

* Refactor to better fit in with existing ThreadFactor utils

* Fix javadocs
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svanoort authored and oleg-nenashev committed Feb 3, 2018
1 parent 6cefcf1 commit 2a6fc653ee7b13adde18515b21f7e6dc1200fa8a
@@ -0,0 +1,26 @@
package hudson.util;

import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;

/**
* Explicitly sets the {@link Thread#contextClassLoader} for threads it creates to its own classloader.
* This avoids issues where threads are lazily created (ex by invoking {@link java.util.concurrent.ScheduledExecutorService#schedule(Runnable, long, TimeUnit)})
* in a context where they would receive a customized {@link Thread#contextClassLoader} that was never meant to be used.
*
* Commonly this is a problem for Groovy use, where this may result in memory leaks.
* @see <a href="https://issues.jenkins-ci.org/browse/JENKINS-49206">JENKINS-49206</a>
*/
public class ClassLoaderSanityThreadFactory implements ThreadFactory {
private final ThreadFactory delegate;

public ClassLoaderSanityThreadFactory(ThreadFactory delegate) {
this.delegate = delegate;
}

@Override public Thread newThread(Runnable r) {
Thread t = delegate.newThread(r);
t.setContextClassLoader(ClassLoaderSanityThreadFactory.class.getClassLoader());
return t;
}
}
@@ -1,6 +1,7 @@
package jenkins.util;

import hudson.security.ACL;
import hudson.util.ClassLoaderSanityThreadFactory;
import hudson.util.DaemonThreadFactory;
import hudson.util.NamingThreadFactory;
import javax.annotation.Nonnull;
@@ -29,7 +30,8 @@
* The scheduled executor thread pool. This is initialized lazily since it may be created/shutdown many times
* when running the test suite.
*/
private static ScheduledExecutorService executorService;
static ScheduledExecutorService executorService;


/**
* Returns the scheduled executor service used by all timed tasks in Jenkins.
@@ -42,7 +44,7 @@ public static synchronized ScheduledExecutorService get() {
// corePoolSize is set to 10, but will only be created if needed.
// ScheduledThreadPoolExecutor "acts as a fixed-sized pool using corePoolSize threads"
// TODO consider also wrapping in ContextResettingExecutorService
executorService = new ImpersonatingScheduledExecutorService(new ErrorLoggingScheduledThreadPoolExecutor(10, new NamingThreadFactory(new DaemonThreadFactory(), "jenkins.util.Timer")), ACL.SYSTEM);
executorService = new ImpersonatingScheduledExecutorService(new ErrorLoggingScheduledThreadPoolExecutor(10, new NamingThreadFactory(new ClassLoaderSanityThreadFactory(new DaemonThreadFactory()), "jenkins.util.Timer")), ACL.SYSTEM);
}
return executorService;
}
@@ -1,12 +1,18 @@
package jenkins.util;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.fail;

import groovy.lang.GroovyClassLoader;
import hudson.triggers.SafeTimerTask;
import org.junit.Assert;
import org.junit.Test;
import org.jvnet.hudson.test.Issue;

import java.net.URLClassLoader;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

public class TimerTest {
@@ -44,4 +50,52 @@ protected void doRun() throws Exception {
}

}

/**
* Launch two tasks which can only complete
* by running doRun() concurrently.
*/
@Test
@Issue("JENKINS-49206")
public void timerBogusClassloader() throws Exception {
final int threadCount = 10; // Twice Timer pool size to ensure we end up creating at least one new thread
final CountDownLatch startLatch = new CountDownLatch(threadCount);

final ClassLoader[] contextClassloaders = new ClassLoader[threadCount];
ScheduledFuture[] futures = new ScheduledFuture[threadCount];
final ClassLoader bogusClassloader = new GroovyClassLoader();

Runnable timerTest = new Runnable() {
@Override
public void run() {
ClassLoader cl = Thread.currentThread().getContextClassLoader();
Thread.currentThread().setContextClassLoader(bogusClassloader);
ScheduledExecutorService exec = Timer.get();
for (int i=0; i<threadCount; i++) {
final int j = i;
futures[j] = exec.schedule(new Runnable() {
@Override
public void run() {
try {
startLatch.countDown();
contextClassloaders[j] = Thread.currentThread().getContextClassLoader();
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
}, 0, TimeUnit.SECONDS);
}
Thread.currentThread().setContextClassLoader(cl);
}
};

Thread t = new Thread(timerTest);
t.run();
t.join(1000L);

for (int i=0; i<threadCount; i++) {
futures[i].get();
Assert.assertEquals(Timer.class.getClassLoader(), contextClassloaders[i]);
}
}
}

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