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