[
https://issues.apache.org/jira/browse/MAPREDUCE-5020?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Trevor Robinson updated MAPREDUCE-5020:
---------------------------------------
Description:
Compiling {{org/apache/hadoop/mapreduce/lib/partition/InputSampler.java}} fails
with the Java 8 preview compiler due to its stricter enforcement of JLS
15.12.2.6 (for [Java
5|http://docs.oracle.com/javase/specs/jls/se5.0/html/expressions.html#15.12.2.6]
or [Java
7|http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.12.2.6]),
which demands that methods applicable via unchecked conversion have their
return type erased:
{noformat}
[ERROR]
hadoop-common/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/partition/InputSampler.java:[320,35]
error: incompatible types: Object[] cannot be converted to K[]
{noformat}
{code}
@SuppressWarnings("unchecked") // getInputFormat, getOutputKeyComparator
public static <K,V> void writePartitionFile(Job job, Sampler<K,V> sampler)
throws IOException, ClassNotFoundException, InterruptedException {
Configuration conf = job.getConfiguration();
final InputFormat inf =
ReflectionUtils.newInstance(job.getInputFormatClass(), conf);
int numPartitions = job.getNumReduceTasks();
K[] samples = sampler.getSample(inf, job); // returns Object[] according to
JLS
{code}
was:
Compiling `org/apache/hadoop/mapreduce/lib/partition/InputSampler.java` fails
with the Java 8 preview compiler due to its stricter enforcement of JLS
15.12.2.6 (for [Java
5|http://docs.oracle.com/javase/specs/jls/se5.0/html/expressions.html#15.12.2.6]
or [Java
7|http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.12.2.6]),
which demands that methods applicable via unchecked conversion have their
return type erased:
{noformat}
[ERROR]
hadoop-common/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/partition/InputSampler.java:[320,35]
error: incompatible types: Object[] cannot be converted to K[]
{noformat}
{code}
@SuppressWarnings("unchecked") // getInputFormat, getOutputKeyComparator
public static <K,V> void writePartitionFile(Job job, Sampler<K,V> sampler)
throws IOException, ClassNotFoundException, InterruptedException {
Configuration conf = job.getConfiguration();
final InputFormat inf =
ReflectionUtils.newInstance(job.getInputFormatClass(), conf);
int numPartitions = job.getNumReduceTasks();
K[] samples = sampler.getSample(inf, job); // returns Object[] according to
JLS
{code}
> Compile failure with JDK8
> -------------------------
>
> Key: MAPREDUCE-5020
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5020
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: client
> Affects Versions: 2.0.3-alpha
> Environment: java version "1.8.0-ea"
> Java(TM) SE Runtime Environment (build 1.8.0-ea-b36e)
> Java HotSpot(TM) Client VM (build 25.0-b04, mixed mode)
> Reporter: Trevor Robinson
> Labels: jdk8
>
> Compiling {{org/apache/hadoop/mapreduce/lib/partition/InputSampler.java}}
> fails with the Java 8 preview compiler due to its stricter enforcement of JLS
> 15.12.2.6 (for [Java
> 5|http://docs.oracle.com/javase/specs/jls/se5.0/html/expressions.html#15.12.2.6]
> or [Java
> 7|http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.12.2.6]),
> which demands that methods applicable via unchecked conversion have their
> return type erased:
> {noformat}
> [ERROR]
> hadoop-common/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/partition/InputSampler.java:[320,35]
> error: incompatible types: Object[] cannot be converted to K[]
> {noformat}
> {code}
> @SuppressWarnings("unchecked") // getInputFormat, getOutputKeyComparator
> public static <K,V> void writePartitionFile(Job job, Sampler<K,V> sampler)
> throws IOException, ClassNotFoundException, InterruptedException {
> Configuration conf = job.getConfiguration();
> final InputFormat inf =
> ReflectionUtils.newInstance(job.getInputFormatClass(), conf);
> int numPartitions = job.getNumReduceTasks();
> K[] samples = sampler.getSample(inf, job); // returns Object[] according
> to JLS
> {code}
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