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Posted to hdfs-issues@hadoop.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2022/08/05 14:54:00 UTC

[jira] [Commented] (HDFS-16524) Add configuration to control blocks deletion asynchronous or synchronous

    [ https://issues.apache.org/jira/browse/HDFS-16524?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17575888#comment-17575888 ] 

ASF GitHub Bot commented on HDFS-16524:
---------------------------------------

ted12138 commented on code in PR #4139:
URL: https://github.com/apache/hadoop/pull/4139#discussion_r938898456


##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java:
##########
@@ -3410,6 +3410,33 @@ FSPermissionChecker getPermissionChecker()
     return dir.getPermissionChecker();
   }
 
+  /**
+   * If blockDeletionAsync enables, blocks will be deleted asynchronously.
+   * If not, incrementally remove the blocks from blockManager
+   * Writelock is dropped and reacquired every BLOCK_DELETION_INCREMENT to
+   * ensure that other waiters on the lock can get in. See HDFS-2938
+   *
+   * @param toDeleteList
+   *          a list of blocks that need to be removed from blocksMap
+   */
+  void removeBlocks(List<BlockInfo> toDeleteList) {
+    if (this.blockDeletionAsync) {
+      blockManager.addBLocksToMarkedDeleteQueue(toDeleteList);
+    } else {
+      Iterator<BlockInfo> iter = toDeleteList.iterator();
+      while (iter.hasNext()) {
+        writeLock();
+        try {
+          for (int i = 0; i < blockDeletionIncrement && iter.hasNext(); i++) {

Review Comment:
   About "blockDeletionIncrement", in my opinion, why we removed it in HDFS-16554 is that we decided to use delete async to replace the previous method, so the "blockDeletionIncrement" won't be used any more. But when we add a switch to control blocks deletion async, we need to save the previous block deletion method, so we still need it.





> Add configuration to control blocks deletion asynchronous or synchronous
> ------------------------------------------------------------------------
>
>                 Key: HDFS-16524
>                 URL: https://issues.apache.org/jira/browse/HDFS-16524
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: namenode
>            Reporter: leo sun
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 50m
>  Remaining Estimate: 0h
>
> When users delete files frequently, deletion is slower than its enqueues. The pending deletions blocks will keep increasing.
> Under this circumstance, deletion synchronous is better.
> So I will add configuration to switch deletion asynchronous or synchronous.



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