[ZOOKEEPER-3361] Add multi version of getChildren request

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Won't Do
• Component/s: java client, server, tests
• Labels: pull-request-available
• Release Note: ZOOKEEPER-3402 already implemented a more general approach which solves this issue as well.
• Assignee: Peter Szecsi
• Reporter: Peter Szecsi
• Created: 12/Apr/19 12:40
• Updated: 01/Aug/19 20:18
• Resolved: 01/Aug/19 20:18

Description

There is already a multi operation for delete, create, setData... However, getChildren has no version of getting the children of multiple nodes by one message.
This could heavily improve the efficiency of a traversal (e.g. breadth-first search) when the latency is high (>1ms). In this case, a simple deleteAll algorithm on 10k nodes takes at least (1ms * 10000 * 2 =) 20 sec, only to acquire the list of the nodes selected for deleting (it has to check for every node whether it has children or not).
I would add a version of getChildren function to the ZooKeeper API which accepts lists as well (containing node paths) and returns their children and introduce a new request type. This way the backward compabilty would not be hurt but ZK could provide a more robust solution for those who may have latency issues.

Issue Links

• Dependent: ZOOKEEPER-3374 Use MultiRead operation in the BFS utility
• links to: GitHub Pull Request #922
• links to: GitHub Pull Request #929