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MAPREDUCE-5974. Allow specifying multiple MapOutputCollectors with fallback. (Todd Lipcon via kasha) 

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1619492 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Karthik Kambatla 2014-08-21 17:37:34 +00:00
parent 7e75226e68
commit e5e9d792c7
4 changed files with 40 additions and 12 deletions
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3
hadoop-mapreduce-project/CHANGES.txt
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@ -187,6 +187,9 @@ Release 2.6.0 - UNRELEASED
MAPREDUCE-5906. Inconsistent configuration in property
"mapreduce.reduce.shuffle.input.buffer.percent" (Akira AJISAKA via aw)
MAPREDUCE-5974. Allow specifying multiple MapOutputCollectors with
fallback. (Todd Lipcon via kasha)
OPTIMIZATIONS
BUG FIXES

37
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java
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@ -381,16 +381,35 @@ public class MapTask extends Task {
private <KEY, VALUE> MapOutputCollector<KEY, VALUE>
createSortingCollector(JobConf job, TaskReporter reporter)
throws IOException, ClassNotFoundException {
MapOutputCollector<KEY, VALUE> collector
= (MapOutputCollector<KEY, VALUE>)
ReflectionUtils.newInstance(
job.getClass(JobContext.MAP_OUTPUT_COLLECTOR_CLASS_ATTR,
MapOutputBuffer.class, MapOutputCollector.class), job);
LOG.info("Map output collector class = " + collector.getClass().getName());
MapOutputCollector.Context context =
new MapOutputCollector.Context(this, job, reporter);
collector.init(context);
return collector;
new MapOutputCollector.Context(this, job, reporter);
Class<?>[] collectorClasses = job.getClasses(
JobContext.MAP_OUTPUT_COLLECTOR_CLASS_ATTR, MapOutputBuffer.class);
int remainingCollectors = collectorClasses.length;
for (Class clazz : collectorClasses) {
try {
if (!MapOutputCollector.class.isAssignableFrom(clazz)) {
throw new IOException("Invalid output collector class: " + clazz.getName() +
" (does not implement MapOutputCollector)");
}
Class<? extends MapOutputCollector> subclazz =
clazz.asSubclass(MapOutputCollector.class);
LOG.debug("Trying map output collector class: " + subclazz.getName());
MapOutputCollector<KEY, VALUE> collector =
ReflectionUtils.newInstance(subclazz, job);
collector.init(context);
LOG.info("Map output collector class = " + collector.getClass().getName());
return collector;
} catch (Exception e) {
String msg = "Unable to initialize MapOutputCollector " + clazz.getName();
if (--remainingCollectors > 0) {
msg += " (" + remainingCollectors + " more collector(s) to try)";
}
LOG.warn(msg, e);
}
}
throw new IOException("Unable to initialize any output collector");
}
@SuppressWarnings("unchecked")

4
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/resources/mapred-default.xml
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@ -408,7 +408,9 @@
<name>mapreduce.job.map.output.collector.class</name>
<value>org.apache.hadoop.mapred.MapTask$MapOutputBuffer</value>
<description>
It defines the MapOutputCollector implementation to use.
The MapOutputCollector implementation(s) to use. This may be a comma-separated
list of class names, in which case the map task will try to initialize each
of the collectors in turn. The first to successfully initialize will be used.
</description>
</property>

8
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/site/apt/PluggableShuffleAndPluggableSort.apt.vm
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@ -71,11 +71,16 @@ Hadoop MapReduce Next Generation - Pluggable Shuffle and Pluggable Sort
*--------------------------------------+---------------------+-----------------+
| <<<mapreduce.job.reduce.shuffle.consumer.plugin.class>>> | <<<org.apache.hadoop.mapreduce.task.reduce.Shuffle>>> | The <<<ShuffleConsumerPlugin>>> implementation to use |
*--------------------------------------+---------------------+-----------------+
| <<<mapreduce.job.map.output.collector.class>>> | <<<org.apache.hadoop.mapred.MapTask$MapOutputBuffer>>> | The <<<MapOutputCollector>>> implementation to use |
| <<<mapreduce.job.map.output.collector.class>>> | <<<org.apache.hadoop.mapred.MapTask$MapOutputBuffer>>> | The <<<MapOutputCollector>>> implementation(s) to use |
*--------------------------------------+---------------------+-----------------+
These properties can also be set in the <<<mapred-site.xml>>> to change the default values for all jobs.
The collector class configuration may specify a comma-separated list of collector implementations.
In this case, the map task will attempt to instantiate each in turn until one of the
implementations successfully initializes. This can be useful if a given collector
implementation is only compatible with certain types of keys or values, for example.
** NodeManager Configuration properties, <<<yarn-site.xml>>> in all nodes:
*--------------------------------------+---------------------+-----------------+
@ -91,4 +96,3 @@ Hadoop MapReduce Next Generation - Pluggable Shuffle and Pluggable Sort
<<<yarn.nodemanager.aux-services>>> property, for example <<<mapred.shufflex>>>.
Then the property defining the corresponding class must be
<<<yarn.nodemanager.aux-services.mapreduce_shufflex.class>>>.