[HBASE-6775] Use ZK.multi when available for HBASE-6710 0.92/0.94 compatibility fix

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.94.2
• Fix Version/s: 0.94.4
• Component/s: Zookeeper

Release Note

hbase.zookeeper.useMulti
Instructs HBase to make use of ZooKeeper's multi-update functionality.
+ This allows certain ZooKeeper operations to complete more quickly and prevents some issues
+ with rare ZooKeeper failure scenarios (see the release note of HBASE-6710 for an example).
+ IMPORTANT: only set this to true if all ZooKeeper servers in the cluster are on version 3.4+
+ and will not be downgraded. ZooKeeper versions before 3.4 do not support multi-update and will
+ not fail gracefully if multi-update is invoked (see ZOOKEEPER-1495).

• Assignee: Gregory Chanan
• Reporter: Gregory Chanan
• Created: 13/Sep/12 20:19
• Updated: 25/Jan/13 12:34
• Resolved: 18/Dec/12 20:14

Description

This issue introduces the ability for the HMaster to make use of ZooKeeper's multi-update functionality. This allows certain ZooKeeper operations to complete more quickly and prevents some issues with rare ZooKeeper failure scenarios (see the release note of HBASE-6710 for an example). This feature is off by default; to enable set "hbase.zookeeper.useMulti" to true in the configuration of the HMaster.

IMPORTANT: "hbase.zookeeper.useMulti" should only be set to true if all ZooKeeper servers in the cluster are on version 3.4+ and will not be downgraded. ZooKeeper versions before 3.4 do not support multi-update and will not fail gracefully if multi-update is invoked (see ZOOKEEPER-1495).

Issue Links

• is related to: HBASE-6710 0.92/0.94 compatibility issues due to HBASE-5206
• relates to: HBASE-7382 Port ZK.multi support from HBASE-6775 to 0.96