[HBASE-6329] Stopping META regionserver when splitting region could cause daughter region to be assigned twice

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.94.0
• Fix Version/s: 0.94.1, 0.95.0
• Component/s: master
• Hadoop Flags: Reviewed
• Assignee: Chunhui Shen
• Reporter: Chunhui Shen
• Created: 05/Jul/12 03:51
• Updated: 26/Feb/13 08:16
• Resolved: 08/Jul/12 19:22

Description

We found this issue in 0.94, first let me describe the case：
Stop META rs when split is in progress

1.Stopping META rs(Server A).
2.The main thread of rs close ZK and delete ephemeral node of the rs.
3.SplitTransaction is retring MetaEditor.addDaughter
4.Master's ServerShutdownHandler process the above dead META server
5.Master fixup daughter and assign the daughter
6.The daughter is opened on another server(Server B)
7.Server A's splitTransaction successfully add the daughter to .META. with serverName=Server A
8.Now, in the .META., daughter's region location is Server A but it is onlined on Server B
9.Restart Master, and master will assign the daughter again.

Attaching the logs, daughter region 80f999ea84cb259e20e9a228546f6c8a

Master log:
2012-07-04 13:45:56,493 INFO org.apache.hadoop.hbase.master.handler.ServerShutdownHandler: Splitting logs for dw93.kgb.sqa.cm4,60020,1341378224464
2012-07-04 13:45:58,983 INFO org.apache.hadoop.hbase.master.handler.ServerShutdownHandler: Fixup; missing daughter writetest,JC\xCA\xC8\xCF<Q\xC49>OH\xCEV\xCC\xC2\xB5\xC2@\xD4,1341380730558.80f999ea84cb259e20e9a228546f6c8a.
2012-07-04 13:45:58,985 INFO org.apache.hadoop.hbase.catalog.MetaEditor: Added daughter writetest,JC\xCA\xC8\xCF<Q\xC49>OH\xCEV\xCC\xC2\xB5\xC2@\xD4,1341380730558.80f999ea84cb259e20e9a228546f6c8a., serverName=null
2012-07-04 13:45:58,988 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Assigning region writetest,JC\xCA\xC8\xCF<Q\xC49>OH\xCEV\xCC\xC2\xB5\xC2@\xD4,1341380730558.80f999ea84cb259e20e9a228546f6c8a. to dw88.kgb.sqa.cm4,60020,1341379188777
2012-07-04 13:46:00,201 INFO org.apache.hadoop.hbase.master.AssignmentManager: The master has opened the region writetest,JC\xCA\xC8\xCF<Q\xC49>OH\xCEV\xCC\xC2\xB5\xC2@\xD4,1341380730558.80f999ea84cb259e20e9a228546f6c8a. that was online on dw88.kgb.sqa.cm4,60020,1341379188777

Master log after restart:
2012-07-04 14:27:05,824 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign: master:60000-0x136187d60e34644 Creating (or updating) unassigned node for 80f999ea84cb259e20e9a228546f6c8a with OFFLINE state
2012-07-04 14:27:05,851 INFO org.apache.hadoop.hbase.master.AssignmentManager: Processing region writetest,JC\xCA\xC8\xCF<Q\xC49>OH\xCEV\xCC\xC2\xB5\xC2@\xD4,1341380730558.80f999ea84cb259e20e9a228546f6c8a. in state M_ZK_REGION_OFFLINE
2012-07-04 14:27:05,854 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Assigning region writetest,JC\xCA\xC8\xCF<Q\xC49>OH\xCEV\xCC\xC2\xB5\xC2@\xD4,1341380730558.80f999ea84cb259e20e9a228546f6c8a. to dw93.kgb.sqa.cm4,60020,1341380812020
2012-07-04 14:27:06,051 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Handling transition=RS_ZK_REGION_OPENED, server=dw93.kgb.sqa.cm4,60020,1341380812020, region=80f999ea84cb259e20e9a228546f6c8a

Regionserver(META rs) log:
2012-07-04 13:45:56,491 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: stopping server dw93.kgb.sqa.cm4,60020,1341378224464; zookeeper connection c
losed.
2012-07-04 13:46:11,951 INFO org.apache.hadoop.hbase.catalog.MetaEditor: Added daughter writetest,JC\xCA\xC8\xCF<Q\xC49>OH\xCEV\xCC\xC2\xB5\xC2@\xD4,1341380730558.80f999ea84cb259e20e9a228546f6c8a., serverName=dw93.kgb.sqa.cm4,60020,1341378224464
2012-07-04 13:46:11,952 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Done with post open deploy task for region=writetest,JC\xCA\xC8\xCF<Q\xC49>OH\xCEV\xCC\xC2\xB5\xC2@\xD4,1341380730558.80f999ea84cb259e20e9a228546f6c8a., daughter=true