org.apache.flink.runtime.execution.librarycache.FlinkUserCodeClassLoaders Maven / Gradle / Ivy
/*
* 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.execution.librarycache;
import org.apache.flink.configuration.CoreOptions;
import org.apache.flink.util.ChildFirstClassLoader;
import org.apache.flink.util.FlinkUserCodeClassLoader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.Closeable;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Enumeration;
import java.util.function.Consumer;
/** Gives the URLClassLoader a nicer name for debugging purposes. */
public class FlinkUserCodeClassLoaders {
private FlinkUserCodeClassLoaders() {}
public static URLClassLoader parentFirst(
URL[] urls,
ClassLoader parent,
Consumer classLoadingExceptionHandler,
boolean checkClassLoaderLeak) {
FlinkUserCodeClassLoader classLoader =
new ParentFirstClassLoader(urls, parent, classLoadingExceptionHandler);
return wrapWithSafetyNet(classLoader, checkClassLoaderLeak);
}
public static URLClassLoader childFirst(
URL[] urls,
ClassLoader parent,
String[] alwaysParentFirstPatterns,
Consumer classLoadingExceptionHandler,
boolean checkClassLoaderLeak) {
FlinkUserCodeClassLoader classLoader =
new ChildFirstClassLoader(
urls, parent, alwaysParentFirstPatterns, classLoadingExceptionHandler);
return wrapWithSafetyNet(classLoader, checkClassLoaderLeak);
}
public static URLClassLoader create(
ResolveOrder resolveOrder,
URL[] urls,
ClassLoader parent,
String[] alwaysParentFirstPatterns,
Consumer classLoadingExceptionHandler,
boolean checkClassLoaderLeak) {
switch (resolveOrder) {
case CHILD_FIRST:
return childFirst(
urls,
parent,
alwaysParentFirstPatterns,
classLoadingExceptionHandler,
checkClassLoaderLeak);
case PARENT_FIRST:
return parentFirst(
urls, parent, classLoadingExceptionHandler, checkClassLoaderLeak);
default:
throw new IllegalArgumentException(
"Unknown class resolution order: " + resolveOrder);
}
}
private static URLClassLoader wrapWithSafetyNet(
FlinkUserCodeClassLoader classLoader, boolean check) {
return check
? new SafetyNetWrapperClassLoader(classLoader, classLoader.getParent())
: classLoader;
}
/** Class resolution order for Flink URL {@link ClassLoader}. */
public enum ResolveOrder {
CHILD_FIRST,
PARENT_FIRST;
public static ResolveOrder fromString(String resolveOrder) {
if (resolveOrder.equalsIgnoreCase("parent-first")) {
return PARENT_FIRST;
} else if (resolveOrder.equalsIgnoreCase("child-first")) {
return CHILD_FIRST;
} else {
throw new IllegalArgumentException("Unknown resolve order: " + resolveOrder);
}
}
}
/**
* Regular URLClassLoader that first loads from the parent and only after that from the URLs.
*/
public static class ParentFirstClassLoader extends FlinkUserCodeClassLoader {
ParentFirstClassLoader(
URL[] urls, ClassLoader parent, Consumer classLoadingExceptionHandler) {
super(urls, parent, classLoadingExceptionHandler);
}
static {
ClassLoader.registerAsParallelCapable();
}
}
/**
* Ensures that holding a reference on the context class loader outliving the scope of user code
* does not prevent the user classloader to be garbage collected (FLINK-16245).
*
* This classloader delegates to the actual user classloader. Upon {@link #close()}, the
* delegate is nulled and can be garbage collected. Additional class resolution will be resolved
* solely through the bootstrap classloader and most likely result in ClassNotFound exceptions.
*/
private static class SafetyNetWrapperClassLoader extends URLClassLoader implements Closeable {
private static final Logger LOG =
LoggerFactory.getLogger(SafetyNetWrapperClassLoader.class);
private volatile FlinkUserCodeClassLoader inner;
SafetyNetWrapperClassLoader(FlinkUserCodeClassLoader inner, ClassLoader parent) {
super(new URL[0], parent);
this.inner = inner;
}
@Override
public void close() {
final FlinkUserCodeClassLoader inner = this.inner;
if (inner != null) {
try {
inner.close();
} catch (IOException e) {
LOG.warn("Could not close user classloader", e);
}
}
this.inner = null;
}
private FlinkUserCodeClassLoader ensureInner() {
if (inner == null) {
throw new IllegalStateException(
"Trying to access closed classloader. Please check if you store "
+ "classloaders directly or indirectly in static fields. If the stacktrace suggests that the leak "
+ "occurs in a third party library and cannot be fixed immediately, you can disable this check "
+ "with the configuration '"
+ CoreOptions.CHECK_LEAKED_CLASSLOADER.key()
+ "'.");
}
return inner;
}
@Override
public Class loadClass(String name) throws ClassNotFoundException {
return ensureInner().loadClass(name);
}
@Override
protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
// called for dynamic class loading
return ensureInner().loadClass(name, resolve);
}
@Override
public URL getResource(String name) {
return ensureInner().getResource(name);
}
@Override
public Enumeration getResources(String name) throws IOException {
return ensureInner().getResources(name);
}
@Override
public URL[] getURLs() {
return ensureInner().getURLs();
}
static {
ClassLoader.registerAsParallelCapable();
}
}
}