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MAPREDUCE-3252. Fix map tasks to not rewrite data an extra time when map output fits in spill buffer. Contributed by Todd Lipcon. 

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1188423 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Todd Lipcon 2011-10-24 22:32:47 +00:00
parent 28d52eabfa
commit 21ded50c4d
2 changed files with 31 additions and 3 deletions
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3
hadoop-mapreduce-project/CHANGES.txt
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@ -1691,6 +1691,9 @@ Release 0.23.0 - Unreleased
MAPREDUCE-3028. Added job-end notification support. (Ravi Prakash via
acmurthy)
MAPREDUCE-3252. Fix map tasks to not rewrite data an extra time when
map output fits in spill buffer. (todd)
Release 0.22.0 - Unreleased
INCOMPATIBLE CHANGES

29
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java
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@ -21,6 +21,7 @@ package org.apache.hadoop.mapred;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.DataOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
@ -36,8 +37,10 @@ import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FileSystem.Statistics;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.LocalFileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.RawLocalFileSystem;
import org.apache.hadoop.io.DataInputBuffer;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.io.SequenceFile;
@ -1727,10 +1730,10 @@ class MapTask extends Task {
finalOutFileSize += rfs.getFileStatus(filename[i]).getLen();
}
if (numSpills == 1) { //the spill is the final output
rfs.rename(filename[0],
sameVolRename(filename[0],
mapOutputFile.getOutputFileForWriteInVolume(filename[0]));
if (indexCacheList.size() == 0) {
rfs.rename(mapOutputFile.getSpillIndexFile(0),
sameVolRename(mapOutputFile.getSpillIndexFile(0),
mapOutputFile.getOutputIndexFileForWriteInVolume(filename[0]));
} else {
indexCacheList.get(0).writeToFile(
@ -1848,6 +1851,28 @@ class MapTask extends Task {
}
}
/**
* Rename srcPath to dstPath on the same volume. This is the same
* as RawLocalFileSystem's rename method, except that it will not
* fall back to a copy, and it will create the target directory
* if it doesn't exist.
*/
private void sameVolRename(Path srcPath,
Path dstPath) throws IOException {
RawLocalFileSystem rfs = (RawLocalFileSystem)this.rfs;
File src = rfs.pathToFile(srcPath);
File dst = rfs.pathToFile(dstPath);
if (!dst.getParentFile().exists()) {
if (!dst.getParentFile().mkdirs()) {
throw new IOException("Unable to rename " + src + " to "
+ dst + ": couldn't create parent directory");
}
}
if (!src.renameTo(dst)) {
throw new IOException("Unable to rename " + src + " to " + dst);
}
}
} // MapOutputBuffer
/**