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HADOOP-17620. DistCp: Use Iterator for listing target directory as well. #2861

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Merged
ayushtkn merged 3 commits into from
Apr 23, 2021
Merged

HADOOP-17620. DistCp: Use Iterator for listing target directory as well. #2861

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e60036b
HADOOP-17620. DistCp: Use Iterator for listing target directory as well.
ayushtkn Apr 4, 2021
468ea21
Fix checkstyle.
ayushtkn Apr 4, 2021
e2fabb9
Fix.
ayushtkn Apr 12, 2021
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5 changes: 3 additions & 2 deletions hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/SimpleCopyListing.java
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,8 @@
* Note: The SimpleCopyListing doesn't handle wild-cards in the input-paths.
*/
public class SimpleCopyListing extends CopyListing {
private static final Logger LOG = LoggerFactory.getLogger(SimpleCopyListing.class);
public static final Logger LOG =
LoggerFactory.getLogger(SimpleCopyListing.class);

public static final int DEFAULT_FILE_STATUS_SIZE = 1000;
public static final boolean DEFAULT_RANDOMIZE_FILE_LISTING = true;
Expand Down Expand Up @@ -601,7 +602,7 @@ public WorkReport<FileStatus[]> processItem(
}

private void printStats() {
LOG.info("Paths (files+dirs) cnt = {}; dirCnt = ", totalPaths, totalDirs);
LOG.info("Paths (files+dirs) cnt = {}; dirCnt = {}", totalPaths, totalDirs);
}

private void maybePrintStats() {
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3 changes: 3 additions & 0 deletions hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/mapred/CopyCommitter.java
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Expand Up @@ -564,12 +564,15 @@ private Path listTargetFiles(final Configuration conf,
// thread count is picked up from the job
int threads = conf.getInt(DistCpConstants.CONF_LABEL_LISTSTATUS_THREADS,
DistCpConstants.DEFAULT_LISTSTATUS_THREADS);
boolean useIterator =
conf.getBoolean(DistCpConstants.CONF_LABEL_USE_ITERATOR, false);
LOG.info("Scanning destination directory {} with thread count: {}",
targetFinalPath, threads);
DistCpOptions options = new DistCpOptions.Builder(targets, resultNonePath)
.withOverwrite(overwrite)
.withSyncFolder(syncFolder)
.withNumListstatusThreads(threads)
.withUseIterator(useIterator)
.build();
DistCpContext distCpContext = new DistCpContext(options);
distCpContext.setTargetPathExists(targetPathExists);
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13 changes: 10 additions & 3 deletions ...oop-distcp/src/test/java/org/apache/hadoop/tools/contract/AbstractContractDistCpTest.java
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Expand Up @@ -42,6 +42,7 @@
import org.apache.hadoop.tools.DistCp;
import org.apache.hadoop.tools.DistCpConstants;
import org.apache.hadoop.tools.DistCpOptions;
import org.apache.hadoop.tools.SimpleCopyListing;
import org.apache.hadoop.tools.mapred.CopyMapper;
import org.apache.hadoop.tools.util.DistCpTestUtils;
import org.apache.hadoop.util.functional.RemoteIterators;
Expand Down Expand Up @@ -628,11 +629,17 @@ public void testDistCpWithIterator() throws Exception {
GenericTestUtils
.createFiles(remoteFS, source, getDepth(), getWidth(), getWidth());

GenericTestUtils.LogCapturer log =
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@steveloughran steveloughran Apr 12, 2021

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Not over-enamoured of this test strategy. As well as being brittle, every use of this is going to complicate our move to Log4J2.

Is there any other way we could do this?

If the distcp test collected the IOStatistics of iteration, then those stores which returned it from iterators (s3a currently, abfs is still WiP) could count it and actually assert on real invocations. HDFS Doesn't do this.

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@ayushtkn ayushtkn Apr 12, 2021 •
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Thanx @steveloughran, do you suggest that we should have two options like -useiteratorforsource and -useiteratorfortarget. Do you think in that case we would be able to save out on memory? since the target list is being build as part of CopyCommitter, so even if one takes the normal path, We would get OOM, just when will differ?

Regarding the log stuff, That was the only thing I could think of, to confirm if iterator was used. And during migration to Log4J2, Will moving to something like this will be of any help instead:
https://github.com/apache/hive/blob/master/ql/src/test/org/apache/hadoop/hive/ql/metadata/TestHive.java#L285

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@steveloughran steveloughran Apr 18, 2021

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  • hive code looks great!

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@ayushtkn ayushtkn Apr 18, 2021

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So, Are you Ok with the other changes? This logger change we can not do now itself in the code, need to do during the migration itself, Was just trying to find a solution to the problem you told, or if there isn't any

GenericTestUtils.LogCapturer.captureLogs(SimpleCopyListing.LOG);

DistCpTestUtils.assertRunDistCp(DistCpConstants.SUCCESS, source.toString(),
dest.toString(), "-useiterator", conf);
dest.toString(), "-useiterator -update -delete", conf);

// Check the target listing was also done using iterator.
Assertions.assertThat(log.getOutput()).contains(
"Building listing using iterator mode for " + dest.toString());

Assertions
.assertThat(RemoteIterators.toList(localFS.listFiles(dest, true)))
Assertions.assertThat(RemoteIterators.toList(localFS.listFiles(dest, true)))
.describedAs("files").hasSize(getTotalFiles());
}

Expand Down