xuanyuanking commented on a change in pull request #32933:
URL: https://github.com/apache/spark/pull/32933#discussion_r661306386
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/state/RocksDBFileManager.scala
##########
@@ -199,6 +199,96 @@ class RocksDBFileManager(
}
}
+ /**
+ * Delete old versions by deleting the associated version and SST files.
+ * At a high-level, this method finds which versions to delete, and which
SST files that were
+ * last used in those versions. Its safe to delete these SST files because a
SST file can
+ * be reused only in successive versions. Therefore, if a SST file F was
last used in version
+ * V, then it wont be used in version V+1 or later, and if version V can be
deleted, then
+ * F can safely be deleted as well.
+ *
+ * To find old files, it does the following.
+ * - List all the existing [version].zip files
+ * - Find the min version that needs to be retained based on the given
`numVersionsToRetain`.
+ * - Accordingly decide which versions should be deleted.
+ * - Resolve all SSTs files of all the existing versions, if not already
resolved.
+ * - Find what was the latest version in which each SST file was used.
+ * - Delete the files that were last used in the to-be-deleted versions as
we will not
+ * need those files any more.
+ *
+ * Note that it only deletes files that it knows are safe to delete.
+ * It may not delete the following files.
+ * - Partially written SST files
+ * - SST files that were used in a version, but that version got overwritten
with a different
+ * set of SST files.
+ */
+ def deleteOldVersions(numVersionsToRetain: Int): Unit = {
+ val path = new Path(dfsRootDir)
+
+ // All versions present in DFS, sorted
+ val sortedVersions = fm.list(path, onlyZipFiles)
+ .map(_.getPath.getName.stripSuffix(".zip"))
+ .map(_.toLong)
+ .sorted
+
+ // Return if no versions generated yet
+ if (sortedVersions.isEmpty) return
+
+ // Find the versions to delete
+ val maxVersionPresent = sortedVersions.last
+ val minVersionPresent = sortedVersions.head
+ val minVersionToRetain =
+ math.max(minVersionPresent, maxVersionPresent - numVersionsToRetain + 1)
+ val versionsToDelete = sortedVersions.takeWhile(_ <
minVersionToRetain).toSet[Long]
+
+ // Return if no version to delete
+ if (versionsToDelete.isEmpty) return
+
+ logInfo(
+ s"Versions present: (min $minVersionPresent, max $maxVersionPresent), " +
+ s"cleaning up all versions older than $minVersionToRetain to retain
last " +
+ s"$numVersionsToRetain versions")
+
+ // Resolve RocksDB files for all the versions and find the max version
each file is used
+ val fileToMaxUsedVersion = new mutable.HashMap[RocksDBImmutableFile, Long]
+ sortedVersions.foreach { version =>
+ val files = Option(versionToRocksDBFiles.get(version)).getOrElse {
+ val newResolvedFiles = getImmutableFilesFromVersionZip(version)
+ versionToRocksDBFiles.put(version, newResolvedFiles)
+ newResolvedFiles
+ }
+ files.foreach(f => fileToMaxUsedVersion(f) = version)
+ }
+
+ // Best effort attempt to delete SST files that were last used in
to-be-deleted versions
+ val filesToDelete = fileToMaxUsedVersion.filter { case (_, v) =>
versionsToDelete.contains(v)}
Review comment:
Thanks, done in the next commit.
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