[jira] [Commented] (HDFS-10458) getFileEncryptionInfo should return quickly for non-encrypted cluster

["Konstantin Shvachko (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-10458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15308994#comment-15308994 ] 

Konstantin Shvachko commented on HDFS-10458:
--------------------------------------------

The patch looks good.
I would add a similar condition for empty {{encryptionZones}} at the start of {{EncryptionZoneManager.getEncryptionZoneForPath()}}. This method is used many times both for write operations, like {{startFile()}} and for reads, like {{getFileInfo()}}. Even though this will still be under the lock, but returning and releasing the lock quickly should be beneficial.

> getFileEncryptionInfo should return quickly for non-encrypted cluster
> ---------------------------------------------------------------------
>
>                 Key: HDFS-10458
>                 URL: https://issues.apache.org/jira/browse/HDFS-10458
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: encryption, namenode
>    Affects Versions: 2.6.0
>            Reporter: Zhe Zhang
>            Assignee: Zhe Zhang
>         Attachments: HDFS-10458.00.patch
>
>
> {{FSDirectory#getFileEncryptionInfo}} always acquires {{readLock}} and checks if the path belongs to an EZ. For a busy system with potentially many listing operations, this could cause locking contention.
> I think we should add a call {{EncryptionZoneManager#hasEncryptionZone()}} to return whether the system has any EZ. If no EZ at all, {{getFileEncryptionInfo}} should return null without {{readLock}}.
> If {{hasEncryptionZone}} is only used in the above scenario, maybe itself doesn't need a {{readLock}} -- if the system doesn't have any EZ when {{getFileEncryptionInfo}} is called on a path, it means the path cannot be encrypted.



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