[GitHub] [kafka] gardnervickers commented on a change in pull request #10896: KAFKA-12964: Collect and rename snapshot files prior to async deletion.

[GitBox <gi...@apache.org>]

gardnervickers commented on a change in pull request #10896:
URL: https://github.com/apache/kafka/pull/10896#discussion_r655545444



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File path: core/src/main/scala/kafka/log/ProducerStateManager.scala
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@@ -828,12 +834,41 @@ class ProducerStateManager(val topicPartition: TopicPartition,
    * Removes the producer state snapshot file metadata corresponding to the provided offset if it exists from this
    * ProducerStateManager, and deletes the backing snapshot file.
    */
-  private[log] def removeAndDeleteSnapshot(snapshotOffset: Long): Unit = {
+  private def removeAndDeleteSnapshot(snapshotOffset: Long): Unit = {
     Option(snapshots.remove(snapshotOffset)).foreach(_.deleteIfExists())
   }
+
+  /**
+   * Removes the producer state snapshot file metadata corresponding to the provided offset if it exists from this
+   * ProducerStateManager, and renames the backing snapshot file to have the Log.DeletionSuffix.
+   *
+   * Note: This method is safe to use with async deletes. If a race occurs and the snapshot file
+   *       is deleted without this ProducerStateManager instance knowing, the resulting exception on
+   *       SnapshotFile rename will be ignored and None will be returned.
+   */
+  private[log] def removeAndMarkSnapshotForDeletion(snapshotOffset: Long): Option[SnapshotFile] = {
+    Option(snapshots.remove(snapshotOffset)).flatMap { snapshot => {
+      // If the file cannot be renamed, it likely means that the file was deleted already.
+      // This can happen due to the way we construct an intermediate producer state manager

Review comment:
       @junrao @kowshik I accidentally included the word `async` here, the deletion performed by the intermediate ProducerStateManager is done synchronously.
   
   I'm referring to the case where we go through `LogLoader.recoverSegment`. We construct a new "intermediate" `ProducerStateManager` for segment recovery which is separate from the "real" `ProducerStateManager` captured in `LoadLogParams`. 
   
   Segment recovery can use the intermediate `ProducerStateManager` to truncate snapshot files via `ProducerStateManager.truncateAndReload` in `Log.rebuildProducerState`. The `SnapshotFile` instances will be removed from the in-memory map for the "intermediate" `ProducerStateManager` in this case, but will remain for the "real" `ProducerStateManager` captured in `LoadLogParams`. 
   
   




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