[jira] [Created] (HBASE-21582) If call HBaseAdmin#snapshotAsync but forget call isSnapshotFinished, then SnapshotHFileCleaner will skip to run every time

["Zheng Hu (JIRA)" <ji...@apache.org>]

Zheng Hu created HBASE-21582:
--------------------------------

             Summary: If call HBaseAdmin#snapshotAsync but forget call isSnapshotFinished, then SnapshotHFileCleaner will skip to run every time
                 Key: HBASE-21582
                 URL: https://issues.apache.org/jira/browse/HBASE-21582
             Project: HBase
          Issue Type: Bug
            Reporter: Zheng Hu
            Assignee: Zheng Hu


This is because we remove the SnapshotSentinel  from snapshotHandlers in SnapshotManager#cleanupSentinels.  Only when the following 3 case, the  cleanupSentinels will be called: 
1.  SnapshotManager#isSnapshotDone; 
2.  SnapshotManager#takeSnapshot; 
3. SnapshotManager#restoreOrCloneSnapshot

So if no isSnapshotDone called, or no further snapshot taking, or snapshot restore/clone.  the SnapshotSentinel will always be keep in snapshotHandlers. 

After HBASE-21387,  Only when no snapshot taking, the SnapshotHFileCleaner will check the unref files and clean. 

I found this bug, because in our XiaoMi branch-2,  we implement the soft delete feature, which means if someone delete a table, then master will create a snapshot firstly, after that, the table deletion begain.  the implementation is quite simple, we use the snapshotManager to create a snapshot. 

{code}
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
index 8f42e4a..6da6a64 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
@@ -2385,12 +2385,6 @@ public class HMaster extends HRegionServer implements MasterServices {
       protected void run() throws IOException {
         getMaster().getMasterCoprocessorHost().preDeleteTable(tableName);
 
+        if (snapshotBeforeDelete) {
+          LOG.info("Take snaposhot for " + tableName + " before deleting");
+          snapshotManager
+              .takeSnapshot(SnapshotDescriptionUtils.getSnapshotNameForDeletedTable(tableName));
+        }
+
         LOG.info(getClientIdAuditPrefix() + " delete " + tableName);
 
         // TODO: We can handle/merge duplicate request
{code}

In the master,  I found the endless log after delete a table: 
{code}
org.apache.hadoop.hbase.master.snapshot.SnapshotFileCache: Not checking unreferenced files since snapshot is running, it will skip to clean the HFiles this time
{code}

This is because the snapshotHandlers never be cleaned after call the  snapshotManager#takeSnapshot.  I think the asynSnapshot may has the same problem. 





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