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[SPARK-13931] Stage can hang if an executor fails while speculated tasks are running

GavinGavinNo1 authored 8 years ago

## What changes were proposed in this pull request?
When function 'executorLost' is invoked in class 'TaskSetManager', it's significant to judge whether variable 'isZombie' is set to true.

This pull request fixes the following hang:

1.Open speculation switch in the application.
2.Run this app and suppose last task of shuffleMapStage 1 finishes. Let's get the record straight, from the eyes of DAG, this stage really finishes, and from the eyes of TaskSetManager, variable 'isZombie' is set to true, but variable runningTasksSet isn't empty because of speculation.
3.Suddenly, executor 3 is lost. TaskScheduler receiving this signal, invokes all executorLost functions of rootPool's taskSetManagers. DAG receiving this signal, removes all this executor's outputLocs.
4.TaskSetManager adds all this executor's tasks to pendingTasks and tells DAG they will be resubmitted (Attention: possibly not on time).
5.DAG starts to submit a new waitingStage, let's say shuffleMapStage 2, and going to find that shuffleMapStage 1 is its missing parent because some outputLocs are removed due to executor lost. Then DAG submits shuffleMapStage 1 again.
6.DAG still receives Task 'Resubmitted' signal from old taskSetManager, and increases the number of pendingTasks of shuffleMapStage 1 each time. However, old taskSetManager won't resolve new task to submit because its variable 'isZombie' is set to true.
7.Finally shuffleMapStage 1 never finishes in DAG together with all stages depending on it.

## How was this patch tested?

It's quite difficult to construct test cases.

Author: GavinGavinNo1 <gavingavinno1@gmail.com>
Author: 16092929 <16092929@cnsuning.com>

Closes #16855 from GavinGavinNo1/resolve-stage-blocked2.

89990a01

89990a01 8 years ago

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Apache Spark

Spark is a fast and general cluster computing system for Big Data. It provides high-level APIs in Scala, Java, Python, and R, and an optimized engine that supports general computation graphs for data analysis. It also supports a rich set of higher-level tools including Spark SQL for SQL and DataFrames, MLlib for machine learning, GraphX for graph processing, and Spark Streaming for stream processing.

http://spark.apache.org/

Online Documentation

You can find the latest Spark documentation, including a programming guide, on the project web page. This README file only contains basic setup instructions.

Building Spark

Spark is built using Apache Maven. To build Spark and its example programs, run:

build/mvn -DskipTests clean package

(You do not need to do this if you downloaded a pre-built package.)

You can build Spark using more than one thread by using the -T option with Maven, see "Parallel builds in Maven 3". More detailed documentation is available from the project site, at "Building Spark".

For general development tips, including info on developing Spark using an IDE, see "Useful Developer Tools".

Interactive Scala Shell

The easiest way to start using Spark is through the Scala shell:

./bin/spark-shell

Try the following command, which should return 1000:

scala> sc.parallelize(1 to 1000).count()

Interactive Python Shell

Alternatively, if you prefer Python, you can use the Python shell:

./bin/pyspark

And run the following command, which should also return 1000:

>>> sc.parallelize(range(1000)).count()

Example Programs

Spark also comes with several sample programs in the examples directory. To run one of them, use ./bin/run-example <class> [params]. For example:

./bin/run-example SparkPi

will run the Pi example locally.

You can set the MASTER environment variable when running examples to submit examples to a cluster. This can be a mesos:// or spark:// URL, "yarn" to run on YARN, and "local" to run locally with one thread, or "local[N]" to run locally with N threads. You can also use an abbreviated class name if the class is in the examples package. For instance:

MASTER=spark://host:7077 ./bin/run-example SparkPi

Many of the example programs print usage help if no params are given.

Running Tests

Testing first requires building Spark. Once Spark is built, tests can be run using:

./dev/run-tests

Please see the guidance on how to run tests for a module, or individual tests.

A Note About Hadoop Versions

Spark uses the Hadoop core library to talk to HDFS and other Hadoop-supported storage systems. Because the protocols have changed in different versions of Hadoop, you must build Spark against the same version that your cluster runs.

Please refer to the build documentation at "Specifying the Hadoop Version" for detailed guidance on building for a particular distribution of Hadoop, including building for particular Hive and Hive Thriftserver distributions.

Configuration

Please refer to the Configuration Guide in the online documentation for an overview on how to configure Spark.

## Contributing

Please review the Contribution to Spark guide for information on how to get started contributing to the project.