[HDFS-5714] Use byte array to represent UnderConstruction feature and Snapshot feature for INodeFile

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: namenode
• Assignee: Jing Zhao
• Reporter: Jing Zhao
• Created: 03/Jan/14 19:22
• Updated: 28/Aug/15 08:37

Description

Currently we define specific classes to represent different INode features, such as FileUnderConstructionFeature and FileWithSnapshotFeature. While recording these feature information in memory, the internal information and object references can still cost a lot of memory. For example, for FileWithSnapshotFeature, not considering the INode's local name, the whole FileDiff list (with size n) can cost around 120n bytes.

In order to decrease the memory usage, we plan to use byte array to record the UnderConstruction feature and Snapshot feature for INodeFile. Specifically, if we use protobuf's encoding, the memory usage for a FileWithSnapshotFeature can be less than 56n bytes.

Issue Links

• is related to: HDFS-6583 Remove clientNode in FileUnderConstructionFeature