[HBASE-7247] Assignment performances decreased by 50% because of regionserver.OpenRegionHandler#tickleOpening

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.95.2
• Fix Version/s: 0.98.0, 0.95.1
• Component/s: master, Region Assignment, regionserver
• Hadoop Flags: Reviewed
• Assignee: Nicolas Liochon
• Reporter: Nicolas Liochon
• Created: 30/Nov/12 17:50
• Updated: 23/Sep/13 19:08
• Resolved: 09/Apr/13 07:13

Description

The regionserver.OpenRegionHandler#tickleOpening updates the region znode as "Do this so master doesn't timeout this region-in-transition.".
However, on the usual test, this makes the assignment time of 1500 regions goes from 70s to 100s, that is, we're 50% slower because of this.
More generally, ZooKeper commits to disk all the data update, and this takes time. Using it to provide a keep alive seems overkill. At the very list, it could be made asynchronous.

I'm not sure how necessary these updates are required (I need to go deeper in the internal, feedback welcome), but it seems very important to optimize this... The trival fix would be to make this optional.

Issue Links

• is required by: HBASE-5843 Improve HBase MTTR - Mean Time To Recover
• requires: HBASE-7407 TestMasterFailover under tests some cases and over tests some others
• requires: HBASE-7327 Assignment Timeouts: Remove the code from the master