WweiL commented on code in PR #48355:
URL: https://github.com/apache/spark/pull/48355#discussion_r1866993275
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sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/state/RocksDB.scala:
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@@ -278,77 +280,185 @@ class RocksDB(
// We send snapshots that needs to be uploaded by the maintenance thread to
this queue
private val snapshotsToUploadQueue = new
ConcurrentLinkedQueue[RocksDBSnapshot]()
+ /**
+ * Based on the ground truth lineage loaded from changelog file (lineage) and
+ * the latest snapshot (version, uniqueId) pair from file listing, this
function finds
+ * the ground truth latest snapshot (version, uniqueId) the db instance
needs to load.
+ *
+ * @param lineage the ground truth lineage loaded from changelog file
+ * @param latestSnapshotVersionsAndUniqueIds
+ * (version, uniqueId) pair of the latest snapshot version. In case of
task re-execution,
+ * the array could have more than one element.
+ * @return the ground truth latest snapshot (version, uniqueId) the db
instance needs to load
+ */
+ private def getLatestSnapshotVersionAndUniqueIdFromLineage(
+ lineage: Array[LineageItem],
+ latestSnapshotVersionsAndUniqueIds: Array[(Long, Option[String])]):
+ (Long, Option[String]) = {
+ lineage.foreach {
+ case LineageItem(version, uniqueId) =>
+ if (latestSnapshotVersionsAndUniqueIds.contains((version,
Some(uniqueId)))) {
+ return (version, Some(uniqueId))
+ }
+ }
+ throw
QueryExecutionErrors.cannotGetLatestSnapshotVersionAndUniqueIdFromLineage(
+ printLineageItems(lineage),
printLineage(latestSnapshotVersionsAndUniqueIds)
+ )
+ }
+
+ /**
+ * Read the lineage from the changelog files. It first get the changelog
reader
+ * of the correct changelog version and then read the lineage information
from the file.
+ * The changelog file is named as version_stateStoreCkptId.changelog
+ * @param version version of the changelog file, used to load changelog file.
+ * @param stateStoreCkptId uniqueId of the changelog file, used to load
changelog file.
+ * @return
+ */
+ private def getLineageFromChangelogFile(
+ version: Long,
+ stateStoreCkptId: Option[String]): Array[LineageItem] = {
+ var changelogReader: StateStoreChangelogReader = null
+ var currLineage: Array[LineageItem] = Array.empty
+ try {
+ changelogReader = fileManager.getChangelogReader(version,
stateStoreCkptId)
+ currLineage = changelogReader.lineage
+ logInfo(log"Loading lineage: " +
+ log"${MDC(LogKeys.LINEAGE, lineageManager)} from " +
+ log"changelog version: ${MDC(LogKeys.VERSION_NUM, version)} " +
+ log"uniqueId: ${MDC(LogKeys.UUID, stateStoreCkptId.getOrElse(""))}.")
+ } finally {
+ if (changelogReader != null) {
+ changelogReader.closeIfNeeded()
+ }
+ }
+ currLineage
+ }
+
+
/**
* Load the given version of data in a native RocksDB instance.
* Note that this will copy all the necessary file from DFS to local disk as
needed,
* and possibly restart the native RocksDB instance.
*/
- def load(
+ private def loadV2(
+ version: Long,
+ stateStoreCkptId: Option[String],
+ readOnly: Boolean = false): RocksDB = {
+ // An array contains lineage information from [snapShotVersion, version]
(inclusive both end)
+ var currVersionLineage: Array[LineageItem] = lineageManager.getLineage()
+ try {
+ if (loadedVersion != version || (loadedStateStoreCkptId.isEmpty ||
+ stateStoreCkptId.get != loadedStateStoreCkptId.get)) {
+ closeDB(ignoreException = false)
+
+ val (latestSnapshotVersion, latestSnapshotUniqueId) = {
+ // Special handling when version is 0.
+ // When loading the very first version (0), stateStoreCkptId does not
need to be defined
+ // because there won't be 0.changelog / 0.zip file created in RocksDB.
+ if (version == 0 && stateStoreCkptId.isEmpty) {
+ (0L, None)
+ // When there is a snapshot file, it is the ground truth, we can skip
+ // reconstructing the lineage from changelog file.
+ } else if (fileManager.existsSnapshotFile(version, stateStoreCkptId)) {
Review Comment:
I think you are suggesting that when `loadedVersion > version`, we should
not reload from the disk and trust everything from the memory (including the
lineage and all other variables including `latestSnapshotVersions`, etc).
Thanks for the suggestion, I agree that we don't do this in this PR because
this is essentially a performance improvement to all rocksDB `loadV1` and
`loadV2` functions, and is beyond the scope of this PR. Let me add the comment.
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