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Reduce Heap Use during Shard Snapshot #60370

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Merged
merged 2 commits into from
Jul 30, 2020
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Reduce Heap Use during Shard Snapshot #60370

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ff6c4d8
Reduce Heap Use during Shard Snapshot
original-brownbear Jul 29, 2020
afc65e7
proper exception
original-brownbear Jul 29, 2020
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105 changes: 60 additions & 45 deletions server/src/main/java/org/elasticsearch/repositories/blobstore/BlobStoreRepository.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1872,63 +1872,78 @@ public void snapshotShard(Store store, MapperService mapperService, SnapshotId s
snapshotStatus.moveToStarted(startTime, indexIncrementalFileCount,
indexTotalNumberOfFiles, indexIncrementalSize, indexTotalFileSize);

final StepListener<Collection<Void>> allFilesUploadedListener = new StepListener<>();
allFilesUploadedListener.whenComplete(v -> {
final IndexShardSnapshotStatus.Copy lastSnapshotStatus =
snapshotStatus.moveToFinalize(snapshotIndexCommit.getGeneration());

// now create and write the commit point
final BlobStoreIndexShardSnapshot snapshot = new BlobStoreIndexShardSnapshot(snapshotId.getName(),
lastSnapshotStatus.getIndexVersion(),
indexCommitPointFiles,
lastSnapshotStatus.getStartTime(),
threadPool.absoluteTimeInMillis() - lastSnapshotStatus.getStartTime(),
lastSnapshotStatus.getIncrementalFileCount(),
lastSnapshotStatus.getIncrementalSize()
);

logger.trace("[{}] [{}] writing shard snapshot file", shardId, snapshotId);
final String indexGeneration;
final boolean writeShardGens = SnapshotsService.useShardGenerations(repositoryMetaVersion);
// build a new BlobStoreIndexShardSnapshot, that includes this one and all the saved ones
List<SnapshotFiles> newSnapshotsList = new ArrayList<>();
newSnapshotsList.add(new SnapshotFiles(snapshotId.getName(), indexCommitPointFiles, shardStateIdentifier));
for (SnapshotFiles point : snapshots) {
newSnapshotsList.add(point);
}
final BlobStoreIndexShardSnapshots updatedBlobStoreIndexShardSnapshots = new BlobStoreIndexShardSnapshots(newSnapshotsList);
final Runnable afterWriteSnapBlob;
if (writeShardGens) {
// When using shard generations we can safely write the index-${uuid} blob before writing out any of the actual data
// for this shard since the uuid named blob will simply not be referenced in case of error and thus we will never
// reference a generation that has not had all its files fully upload.
indexGeneration = UUIDs.randomBase64UUID();
try {
INDEX_SHARD_SNAPSHOT_FORMAT.write(snapshot, shardContainer, snapshotId.getUUID(), compress);
writeShardIndexBlob(shardContainer, indexGeneration, updatedBlobStoreIndexShardSnapshots);
} catch (IOException e) {
throw new IndexShardSnapshotFailedException(shardId, "Failed to write commit point", e);
}
// build a new BlobStoreIndexShardSnapshot, that includes this one and all the saved ones
List<SnapshotFiles> newSnapshotsList = new ArrayList<>();
newSnapshotsList.add(new SnapshotFiles(snapshot.snapshot(), snapshot.indexFiles(), shardStateIdentifier));
for (SnapshotFiles point : snapshots) {
newSnapshotsList.add(point);
throw new IndexShardSnapshotFailedException(shardId,
"Failed to write shard level snapshot metadata for [" + snapshotId + "] to ["
+ INDEX_SHARD_SNAPSHOTS_FORMAT.blobName(indexGeneration) + "]", e);
}
final List<String> blobsToDelete;
final String indexGeneration;
final boolean writeShardGens = SnapshotsService.useShardGenerations(repositoryMetaVersion);
if (writeShardGens) {
indexGeneration = UUIDs.randomBase64UUID();
blobsToDelete = Collections.emptyList();
} else {
indexGeneration = Long.toString(Long.parseLong(fileListGeneration) + 1);
// Delete all previous index-N blobs
blobsToDelete = blobs.stream().filter(blob -> blob.startsWith(SNAPSHOT_INDEX_PREFIX)).collect(Collectors.toList());
assert blobsToDelete.stream().mapToLong(b -> Long.parseLong(b.replaceFirst(SNAPSHOT_INDEX_PREFIX, "")))
afterWriteSnapBlob = () -> {};
} else {
// When not using shard generations we can only write the index-${N} blob after all other work for this shard has
// completed.
// Also, in case of numeric shard generations the data node has to take care of deleting old shard generations.
indexGeneration = Long.toString(Long.parseLong(fileListGeneration) + 1);
// Delete all previous index-N blobs
final List<String> blobsToDelete = blobs.stream().filter(blob -> blob.startsWith(SNAPSHOT_INDEX_PREFIX))
.collect(Collectors.toList());
assert blobsToDelete.stream().mapToLong(b -> Long.parseLong(b.replaceFirst(SNAPSHOT_INDEX_PREFIX, "")))
.max().orElse(-1L) < Long.parseLong(indexGeneration)
: "Tried to delete an index-N blob newer than the current generation [" + indexGeneration
+ "] when deleting index-N blobs " + blobsToDelete;
}
try {
writeShardIndexBlob(shardContainer, indexGeneration, new BlobStoreIndexShardSnapshots(newSnapshotsList));
} catch (IOException e) {
throw new IndexShardSnapshotFailedException(shardId,
"Failed to finalize snapshot creation [" + snapshotId + "] with shard index ["
+ INDEX_SHARD_SNAPSHOTS_FORMAT.blobName(indexGeneration) + "]", e);
}
if (writeShardGens == false) {
afterWriteSnapBlob = () -> {
try {
writeShardIndexBlob(shardContainer, indexGeneration, updatedBlobStoreIndexShardSnapshots);
} catch (IOException e) {
throw new IndexShardSnapshotFailedException(shardId,
"Failed to finalize snapshot creation [" + snapshotId + "] with shard index ["
+ INDEX_SHARD_SNAPSHOTS_FORMAT.blobName(indexGeneration) + "]", e);
}
try {
deleteFromContainer(shardContainer, blobsToDelete);
} catch (IOException e) {
logger.warn(() -> new ParameterizedMessage("[{}][{}] failed to delete old index-N blobs during finalization",
snapshotId, shardId), e);
snapshotId, shardId), e);
}
};
}

final StepListener<Collection<Void>> allFilesUploadedListener = new StepListener<>();
allFilesUploadedListener.whenComplete(v -> {
final IndexShardSnapshotStatus.Copy lastSnapshotStatus =
snapshotStatus.moveToFinalize(snapshotIndexCommit.getGeneration());

// now create and write the commit point
logger.trace("[{}] [{}] writing shard snapshot file", shardId, snapshotId);
try {
INDEX_SHARD_SNAPSHOT_FORMAT.write(new BlobStoreIndexShardSnapshot(snapshotId.getName(),
lastSnapshotStatus.getIndexVersion(),
indexCommitPointFiles,
lastSnapshotStatus.getStartTime(),
threadPool.absoluteTimeInMillis() - lastSnapshotStatus.getStartTime(),
lastSnapshotStatus.getIncrementalFileCount(),
lastSnapshotStatus.getIncrementalSize()
), shardContainer, snapshotId.getUUID(), compress);
} catch (IOException e) {
throw new IndexShardSnapshotFailedException(shardId, "Failed to write commit point", e);
}
afterWriteSnapBlob.run();
snapshotStatus.moveToDone(threadPool.absoluteTimeInMillis(), indexGeneration);
listener.onResponse(indexGeneration);
}, listener::onFailure);
Expand Down