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HDFS-15937. Reduce memory used during datanode layout upgrade. Contributed by Stephen O'Donnell (#2838)

This commit is contained in:
Stephen O'Donnell 2021-04-08 11:59:02 +01:00 committed by GitHub
parent ca9aa91d10
commit 4c567fcff7
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 62 additions and 36 deletions
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98
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java
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@ -1071,12 +1071,26 @@ public class DataStorage extends Storage {
}
private static class LinkArgs {
File src;
File dst;
private File srcDir;
private File dstDir;
private String blockFile;
LinkArgs(File src, File dst) {
this.src = src;
this.dst = dst;
LinkArgs(File srcDir, File dstDir, String blockFile) {
this.srcDir = srcDir;
this.dstDir = dstDir;
this.blockFile = blockFile;
}
public File src() {
return new File(srcDir, blockFile);
}
public File dst() {
return new File(dstDir, blockFile);
}
public String blockFile() {
return blockFile;
}
}
@ -1102,8 +1116,9 @@ public class DataStorage extends Storage {
}
final ArrayList<LinkArgs> idBasedLayoutSingleLinks = Lists.newArrayList();
linkBlocksHelper(from, to, oldLV, hl, upgradeToIdBasedLayout, to,
idBasedLayoutSingleLinks);
final Map<File, File> pathCache = new HashMap<>();
linkBlocksHelper(from, to, hl, upgradeToIdBasedLayout, to,
idBasedLayoutSingleLinks, pathCache);
// Detect and remove duplicate entries.
final ArrayList<LinkArgs> duplicates =
@ -1129,7 +1144,7 @@ public class DataStorage extends Storage {
idBasedLayoutSingleLinks.size());
for (int j = iCopy; j < upperBound; j++) {
LinkArgs cur = idBasedLayoutSingleLinks.get(j);
HardLink.createHardLink(cur.src, cur.dst);
HardLink.createHardLink(cur.src(), cur.dst());
}
return null;
}
@ -1162,9 +1177,9 @@ public class DataStorage extends Storage {
@Override
public int compare(LinkArgs a, LinkArgs b) {
return ComparisonChain.start().
compare(a.src.getName(), b.src.getName()).
compare(a.src, b.src).
compare(a.dst, b.dst).
compare(a.blockFile(), b.blockFile()).
compare(a.src(), b.src()).
compare(a.dst(), b.dst()).
result();
}
});
@ -1174,8 +1189,8 @@ public class DataStorage extends Storage {
boolean addedPrev = false;
for (int i = 0; i < all.size(); i++) {
LinkArgs args = all.get(i);
long blockId = Block.getBlockId(args.src.getName());
boolean isMeta = Block.isMetaFilename(args.src.getName());
long blockId = Block.getBlockId(args.blockFile());
boolean isMeta = Block.isMetaFilename(args.blockFile());
if ((prevBlockId == null) ||
(prevBlockId.longValue() != blockId)) {
prevBlockId = blockId;
@ -1214,10 +1229,10 @@ public class DataStorage extends Storage {
TreeMap<Long, List<LinkArgs>> highestGenstamps =
new TreeMap<Long, List<LinkArgs>>();
for (LinkArgs duplicate : duplicates) {
if (!Block.isMetaFilename(duplicate.src.getName())) {
if (!Block.isMetaFilename(duplicate.blockFile())) {
continue;
}
long blockId = Block.getBlockId(duplicate.src.getName());
long blockId = Block.getBlockId(duplicate.blockFile());
List<LinkArgs> prevHighest = highestGenstamps.get(blockId);
if (prevHighest == null) {
List<LinkArgs> highest = new LinkedList<LinkArgs>();
@ -1226,8 +1241,8 @@ public class DataStorage extends Storage {
continue;
}
long prevGenstamp =
Block.getGenerationStamp(prevHighest.get(0).src.getName());
long genstamp = Block.getGenerationStamp(duplicate.src.getName());
Block.getGenerationStamp(prevHighest.get(0).blockFile());
long genstamp = Block.getGenerationStamp(duplicate.blockFile());
if (genstamp < prevGenstamp) {
continue;
}
@ -1241,19 +1256,19 @@ public class DataStorage extends Storage {
// from the duplicates list.
for (Iterator<LinkArgs> iter = duplicates.iterator(); iter.hasNext(); ) {
LinkArgs duplicate = iter.next();
long blockId = Block.getBlockId(duplicate.src.getName());
long blockId = Block.getBlockId(duplicate.blockFile());
List<LinkArgs> highest = highestGenstamps.get(blockId);
if (highest != null) {
boolean found = false;
for (LinkArgs high : highest) {
if (high.src.getParent().equals(duplicate.src.getParent())) {
if (high.src().getParent().equals(duplicate.src().getParent())) {
found = true;
break;
}
}
if (!found) {
LOG.warn("Unexpectedly low genstamp on {}.",
duplicate.src.getAbsolutePath());
duplicate.src().getAbsolutePath());
iter.remove();
}
}
@ -1264,25 +1279,25 @@ public class DataStorage extends Storage {
// preserving one block file / metadata file pair.
TreeMap<Long, LinkArgs> longestBlockFiles = new TreeMap<Long, LinkArgs>();
for (LinkArgs duplicate : duplicates) {
if (Block.isMetaFilename(duplicate.src.getName())) {
if (Block.isMetaFilename(duplicate.blockFile())) {
continue;
}
long blockId = Block.getBlockId(duplicate.src.getName());
long blockId = Block.getBlockId(duplicate.blockFile());
LinkArgs prevLongest = longestBlockFiles.get(blockId);
if (prevLongest == null) {
longestBlockFiles.put(blockId, duplicate);
continue;
}
long blockLength = duplicate.src.length();
long prevBlockLength = prevLongest.src.length();
long blockLength = duplicate.src().length();
long prevBlockLength = prevLongest.src().length();
if (blockLength < prevBlockLength) {
LOG.warn("Unexpectedly short length on {}.",
duplicate.src.getAbsolutePath());
duplicate.src().getAbsolutePath());
continue;
}
if (blockLength > prevBlockLength) {
LOG.warn("Unexpectedly short length on {}.",
prevLongest.src.getAbsolutePath());
prevLongest.src().getAbsolutePath());
}
longestBlockFiles.put(blockId, duplicate);
}
@ -1291,21 +1306,22 @@ public class DataStorage extends Storage {
// arbitrarily selected by us.
for (Iterator<LinkArgs> iter = all.iterator(); iter.hasNext(); ) {
LinkArgs args = iter.next();
long blockId = Block.getBlockId(args.src.getName());
long blockId = Block.getBlockId(args.blockFile());
LinkArgs bestDuplicate = longestBlockFiles.get(blockId);
if (bestDuplicate == null) {
continue; // file has no duplicates
}
if (!bestDuplicate.src.getParent().equals(args.src.getParent())) {
LOG.warn("Discarding {}.", args.src.getAbsolutePath());
if (!bestDuplicate.src().getParent().equals(args.src().getParent())) {
LOG.warn("Discarding {}.", args.src().getAbsolutePath());
iter.remove();
}
}
}
static void linkBlocksHelper(File from, File to, int oldLV, HardLink hl,
boolean upgradeToIdBasedLayout, File blockRoot,
List<LinkArgs> idBasedLayoutSingleLinks) throws IOException {
static void linkBlocksHelper(File from, File to, HardLink hl,
boolean upgradeToIdBasedLayout, File blockRoot,
List<LinkArgs> idBasedLayoutSingleLinks, Map<File, File> pathCache)
throws IOException {
if (!from.exists()) {
return;
}
@ -1345,8 +1361,18 @@ public class DataStorage extends Storage {
throw new IOException("Failed to mkdirs " + blockLocation);
}
}
idBasedLayoutSingleLinks.add(new LinkArgs(new File(from, blockName),
new File(blockLocation, blockName)));
/**
* The destination path is 32x32, so 1024 distinct paths. Therefore
* we cache the destination path and reuse the same File object on
* potentially thousands of blocks located on this volume.
* This method is called recursively so the cache is passed through
* each recursive call. There is one cache per volume, and it is only
* accessed by a single thread so no locking is needed.
*/
File cachedDest = pathCache
.computeIfAbsent(blockLocation, k -> blockLocation);
idBasedLayoutSingleLinks.add(new LinkArgs(from,
cachedDest, blockName));
hl.linkStats.countSingleLinks++;
}
} else {
@ -1369,8 +1395,8 @@ public class DataStorage extends Storage {
if (otherNames != null) {
for (int i = 0; i < otherNames.length; i++) {
linkBlocksHelper(new File(from, otherNames[i]),
new File(to, otherNames[i]), oldLV, hl, upgradeToIdBasedLayout,
blockRoot, idBasedLayoutSingleLinks);
new File(to, otherNames[i]), hl, upgradeToIdBasedLayout,
blockRoot, idBasedLayoutSingleLinks, pathCache);
}
}
}