[HBASE-14190] Assign system tables ahead of user region assignment

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Not A Problem
• Component/s: Region Assignment
• Assignee: Unassigned
• Reporter: Ted Yu
• Created: 06/Aug/15 16:32
• Updated: 17/Jun/22 18:13
• Resolved: 11/Jun/22 18:12

Description

Currently the namespace table region is assigned like user regions.

I spent several hours working with a customer where master couldn't finish initialization.
Even though master was restarted quite a few times, it went down with the following:

2015-08-05 17:16:57,530 FATAL [hdpmaster1:60000.activeMasterManager] master.HMaster: Master server abort: loaded coprocessors are: []
2015-08-05 17:16:57,530 FATAL [hdpmaster1:60000.activeMasterManager] master.HMaster: Unhandled exception. Starting shutdown.
java.io.IOException: Timedout 300000ms waiting for namespace table to be assigned
  at org.apache.hadoop.hbase.master.TableNamespaceManager.start(TableNamespaceManager.java:104)
  at org.apache.hadoop.hbase.master.HMaster.initNamespace(HMaster.java:985)
  at org.apache.hadoop.hbase.master.HMaster.finishActiveMasterInitialization(HMaster.java:779)
  at org.apache.hadoop.hbase.master.HMaster.access$500(HMaster.java:182)
  at org.apache.hadoop.hbase.master.HMaster$1.run(HMaster.java:1646)
  at java.lang.Thread.run(Thread.java:744)

During previous run(s), namespace table was created, hence leaving an entry in hbase:meta.
The following if block in TableNamespaceManager#start() was skipped:

    if (!MetaTableAccessor.tableExists(masterServices.getConnection(),
      TableName.NAMESPACE_TABLE_NAME)) {

TableNamespaceManager#start() spins, waiting for namespace region to be assigned.
There was issue in master assigning user regions.
We tried issuing 'assign' command from hbase shell which didn't work because of the following check in MasterRpcServices#assignRegion():

      master.checkInitialized();

This scenario can be avoided if we assign hbase:namespace table after hbase:meta is assigned but before user table region assignment.

Issue Links

• relates to: HBASE-13556 In assignment, treat system tables as 'special'; assign after hbase:meta and before user-space tables
• relates to: HBASE-18865 Ensure system tables can have their WALs split prior to user tables

Sub-Tasks

• Implement dedicated WAL for system tables: Open