[jira] [Resolved] (HBASE-9270) [0.94] FSTableDescriptors caching is racy

["stack (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-9270?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

stack resolved HBASE-9270.
--------------------------
    Resolution: Won't Fix

Resolving a 0.94 issue not being worked on.

> [0.94] FSTableDescriptors caching is racy
> -----------------------------------------
>
>                 Key: HBASE-9270
>                 URL: https://issues.apache.org/jira/browse/HBASE-9270
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.94.11
>            Reporter: Andrew Purtell
>            Assignee: Rekha Joshi
>            Priority: Minor
>         Attachments: HBASE-9270.1.patch
>
>
> An occasionally failing test in 0.92 branch that concurrently executes master operations on a single table found this problem in FSTableDescriptors:
> {code}
> diff --git src/main/java/org/apache/hadoop/hbase/util/FSTableDescriptors.java src/main/java/org/apache/hadoop/hbase/util/FSTableDescriptors.java
> index e882621..b0042cd 100644
> --- src/main/java/org/apache/hadoop/hbase/util/FSTableDescriptors.java
> +++ src/main/java/org/apache/hadoop/hbase/util/FSTableDescriptors.java
> @@ -221,8 +221,15 @@ public class FSTableDescriptors implements TableDescriptors {
>      if (HConstants.HBASE_NON_USER_TABLE_DIRS.contains(htd.getNameAsString())) {
>        throw new NotImplementedException();
>      }
> -    if (!this.fsreadonly) updateHTableDescriptor(this.fs, this.rootdir, htd);
> -    long modtime = getTableInfoModtime(this.fs, this.rootdir, htd.getNameAsString());
> +    if (fsreadonly) {
> +      // Cannot cache here.
> +      // We can't know if a modtime from the most recent file found in a
> +      // directory listing at some arbitrary point in time still corresponds
> +      // to the latest, nor that our htd is the latest.
> +      return;
> +    }
> +    // Cache with the modtime of the descriptor we wrote
> +    long modtime = updateHTableDescriptor(this.fs, this.rootdir, htd).getModificationTime();
>      this.cache.put(htd.getNameAsString(), new TableDescriptorModtime(modtime, htd));
>    }
> {code}
> After HBASE-7305 master operations are serialized by a write lock on the table.
> However, 0.94 has code with the same issue:
> {code}
>   @Override
>   public void add(HTableDescriptor htd) throws IOException {
>     if (Bytes.equals(HConstants.ROOT_TABLE_NAME, htd.getName())) {
>       throw new NotImplementedException();
>     }
>     if (Bytes.equals(HConstants.META_TABLE_NAME, htd.getName())) {
>       throw new NotImplementedException();
>     }
>     if (HConstants.HBASE_NON_USER_TABLE_DIRS.contains(htd.getNameAsString())) {
>       throw new NotImplementedException();
>     }
>     if (!this.fsreadonly) updateHTableDescriptor(this.fs, this.rootdir, htd);
>     String tableName = htd.getNameAsString();
>     long modtime = getTableInfoModtime(this.fs, this.rootdir, tableName);
>     long dirmodtime = getTableDirModtime(this.fs, this.rootdir, tableName);
>     this.cache.put(tableName, new TableDescriptorModtime(modtime, dirmodtime, htd));
>   }
> {code}



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