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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-8360) Implement task-local state recovery
Date Thu, 01 Feb 2018 11:07:01 GMT

    [ https://issues.apache.org/jira/browse/FLINK-8360?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16348405#comment-16348405
] 

ASF GitHub Bot commented on FLINK-8360:
---------------------------------------

Github user tillrohrmann commented on a diff in the pull request:

    https://github.com/apache/flink/pull/5239#discussion_r165323575
  
    --- Diff: flink-core/src/test/java/org/apache/flink/util/MethodForwardingTestUtil.java
---
    @@ -0,0 +1,146 @@
    +/*
    + * 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.util;
    +
    +import org.mockito.Mockito;
    +
    +import java.lang.reflect.Array;
    +import java.lang.reflect.Method;
    +import java.util.Collections;
    +import java.util.Set;
    +import java.util.function.Function;
    +
    +import static org.junit.Assert.fail;
    +import static org.mockito.Mockito.reset;
    +import static org.mockito.Mockito.spy;
    +
    +/**
    + * Helper class with a method that attempt to automatically test method forwarding between
a delegate and a wrapper.
    + */
    +public class MethodForwardingTestUtil {
    +
    +	/**
    +	 * This is a best effort automatic test for method forwarding between a delegate and
its wrapper, where the wrapper
    +	 * class is a subtype of the delegate. This ignores methods that are inherited from
Object.
    +	 *
    +	 * @param delegateClass the class for the delegate.
    +	 * @param wrapperFactory factory that produces a wrapper from a delegate.
    +	 * @param <D> type of the delegate
    +	 * @param <W> type of the wrapper
    +	 */
    +	public static <D, W> void testMethodForwarding(
    +		Class<D> delegateClass,
    +		Function<D, W> wrapperFactory) {
    +		testMethodForwarding(delegateClass, wrapperFactory, Collections.emptySet());
    +	}
    +
    +	/**
    +	 * This is a best effort automatic test for method forwarding between a delegate and
its wrapper, where the wrapper
    +	 * class is a subtype of the delegate. Methods can be remapped in case that the implementation
does not call the
    +	 * original method. Remapping to null skips the method. This ignores methods that are
inherited from Object.
    +	 *
    +	 * @param delegateClass the class for the delegate.
    +	 * @param wrapperFactory factory that produces a wrapper from a delegate.
    +	 * @param skipMethodSet set of methods to ignore.
    +	 * @param <D> type of the delegate
    +	 * @param <W> type of the wrapper
    +	 */
    +	public static <D, W> void testMethodForwarding(
    +		Class<D> delegateClass,
    +		Function<D, W> wrapperFactory,
    +		Set<Method> skipMethodSet) {
    +
    +		Preconditions.checkNotNull(delegateClass);
    +		Preconditions.checkNotNull(wrapperFactory);
    +		Preconditions.checkNotNull(skipMethodSet);
    +
    +		D delegate = spy(delegateClass);
    +		W wrapper = wrapperFactory.apply(delegate);
    +
    +		// ensure that wrapper is a subtype of delegate
    +		Preconditions.checkArgument(delegateClass.isAssignableFrom(wrapper.getClass()));
    +
    +		for (Method delegateMethod : delegateClass.getMethods()) {
    +
    +			if (checkSkipMethodForwardCheck(delegateMethod, skipMethodSet)) {
    +				continue;
    +			}
    +
    +			try {
    +				// find the correct method to substitute the bridge for erased generic types.
    +				// if this doesn't work, the user need to exclude the method and write an additional
test.
    +				Method wrapperMethod = wrapper.getClass().getDeclaredMethod(
    +					delegateMethod.getName(),
    +					delegateMethod.getParameterTypes());
    +
    +				// things get a bit fuzzy here, best effort to find a match but this might end up
with a wrong method.
    +				if (wrapperMethod.isBridge()) {
    +					for (Method method : wrapper.getClass().getDeclaredMethods()) {
    +						if (!method.isBridge()
    +							&& method.getName().equals(wrapperMethod.getName())
    +							&& method.getParameterCount() == wrapperMethod.getParameterCount()) {
    +							wrapperMethod = method;
    +							break;
    +						}
    +					}
    +				}
    +
    +				Class<?>[] parameterTypes = wrapperMethod.getParameterTypes();
    +				Object[] arguments = new Object[parameterTypes.length];
    +				for (int j = 0; j < arguments.length; j++) {
    +					Class<?> parameterType = parameterTypes[j];
    +					if (parameterType.isArray()) {
    +						arguments[j] = Array.newInstance(parameterType.getComponentType(), 0);
    +					} else if (parameterType.isPrimitive()) {
    +						arguments[j] = 0;
    +					} else {
    +						arguments[j] = Mockito.mock(parameterType);
    +					}
    +				}
    +
    +				wrapperMethod.invoke(wrapper, arguments);
    +				delegateMethod.invoke(Mockito.verify(delegate, Mockito.times(1)), arguments);
    +				reset(delegate);
    +			} catch (Exception ex) {
    +				ex.printStackTrace();
    +				fail("Forwarding test failed: " + ex.getMessage());
    --- End diff --
    
    I think we should let the exception propagate.


> Implement task-local state recovery
> -----------------------------------
>
>                 Key: FLINK-8360
>                 URL: https://issues.apache.org/jira/browse/FLINK-8360
>             Project: Flink
>          Issue Type: New Feature
>          Components: State Backends, Checkpointing
>            Reporter: Stefan Richter
>            Assignee: Stefan Richter
>            Priority: Major
>             Fix For: 1.5.0
>
>
> This issue tracks the development of recovery from task-local state. The main idea is
to have a secondary, local copy of the checkpointed state, while there is still a primary
copy in DFS that we report to the checkpoint coordinator.
> Recovery can attempt to restore from the secondary local copy, if available, to save
network bandwidth. This requires that the assignment from tasks to slots is as sticky is possible.
> For starters, we will implement this feature for all managed keyed states and can easily
enhance it to all other state types (e.g. operator state) later.



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