[jira] [Created] (HBASE-20919) meta region can`t reonline when restart when open rsgroup

["chenyang (JIRA)" <ji...@apache.org>]

chenyang created HBASE-20919:
--------------------------------

             Summary: meta region can`t reonline when restart when open rsgroup
                 Key: HBASE-20919
                 URL: https://issues.apache.org/jira/browse/HBASE-20919
             Project: HBase
          Issue Type: Bug
          Components: Balancer, master, rsgroup
    Affects Versions: 2.0.1
            Reporter: chenyang
         Attachments: bug2.png

if you open rsgroup, hbase-site.xml contains  below configuration.

{code:java}
// code placeholder
<property>
<name>hbase.coprocessor.master.classes</name>
<value>org.apache.hadoop.hbase.rsgroup.RSGroupAdminEndpoint</value>
</property>
<property>
<name>hbase.master.loadbalancer.class</name>
<value>org.apache.hadoop.hbase.rsgroup.RSGroupBasedLoadBalancer</value>
</property>
{code}
And you shut down the whole HBase cluster in the way:
 # first shut down region server one by one
 # shut down master

Then you restart whole cluster in the way:
 # start master
 # start regionserver

The hbase:meta region can not be re-online and the the rsgroup can not be initialized successfully.
master logs:
{code:java}
// code placeholder

2018-07-12 18:27:08,775 INFO [org.apache.hadoop.hbase.rsgroup.RSGroupInfoManagerImpl$RSGroupStartupWorker-bjpg-rs4730.yz02,16000,1531389637409] rsgroup.RSGro
upInfoManagerImpl$RSGroupStartupWorker: Waiting for catalog tables to come online
2018-07-12 18:27:08,876 INFO [org.apache.hadoop.hbase.rsgroup.RSGroupInfoManagerImpl$RSGroupStartupWorker-bjpg-rs4730.yz02,16000,1531389637409] zookeeper.Met
aTableLocator: Failed verification of hbase:meta,,1 at address=bjpg-rs4732.yz02,60020,1531388712053, exception=org.apache.hadoop.hbase.NotServingRegionExcepti
on: hbase:meta,,1 is not online on bjpg-rs4732.yz02,60020,1531389727928
at org.apache.hadoop.hbase.regionserver.HRegionServer.getRegionByEncodedName(HRegionServer.java:3249)
at org.apache.hadoop.hbase.regionserver.HRegionServer.getRegion(HRegionServer.java:3226)
at org.apache.hadoop.hbase.regionserver.RSRpcServices.getRegion(RSRpcServices.java:1414)
at org.apache.hadoop.hbase.regionserver.RSRpcServices.getRegionInfo(RSRpcServices.java:1729)
at org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos$AdminService$2.callBlockingMethod(AdminProtos.java:28286)
at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:409)
at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:130)
at org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:324)
at org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:304)
{code}
The logs show that hbase:meta region is not online and rsgroup keeps retrying to initialize.
 
but why the hbase:meta region is not online?
The info-level logs and jstack had not enough infomation, so I added some debug logs in test-source-code. Then i checked the master`s logs and region server`s logs, and found the meta region assign procedure which hold the meta region lock not completed and not released the lock forever, so the recoverMetaProcedure could not be executed. 
 
Why the first procedure not completed and not released meta region lock?
In the test logs, i found when assignmentManager assigned the region, it need to call the rsgroup balancer which  have not been initialized completely, so throw NPE.  As a result, the procedure not completed and not released the lock forever.
{code:java}
// code placeholder
java.lang.NullPointerException
at org.apache.hadoop.hbase.rsgroup.RSGroupBasedLoadBalancer.generateGroupMaps(RSGroupBasedLoadBalancer.java:262)
at org.apache.hadoop.hbase.rsgroup.RSGroupBasedLoadBalancer.roundRobinAssignment(RSGroupBasedLoadBalancer.java:162)
at org.apache.hadoop.hbase.master.assignment.AssignmentManager.processAssignmentPlans(AssignmentManager.java:1864)
at org.apache.hadoop.hbase.master.assignment.AssignmentManager.processAssignQueue(AssignmentManager.java:1809)
at org.apache.hadoop.hbase.master.assignment.AssignmentManager.access$400(AssignmentManager.java:113)
at org.apache.hadoop.hbase.master.assignment.AssignmentManager$2.run(AssignmentManager.java:1693)
{code}
As shown in the figure named bug2.png listed in attachments, when we shutdown the last region server, the master submit a ServerCrashProcedure. In the procedure, it will reassign hbase:meta region, but at that moment, there is no online region server, so the procedure can not be executed completely. Then we shut down master, the ServerCrashProcedure and it`a subProcedures are stored into procedureStore.
 
When we restart master, at first,  the master blocks waiting for becoming active master.  after becoming active master, it starts procedureExecutor. The procedureExecutor start to read procedure from procedureStore and the pre serverCrashProcedure submit a assign region task to assignmentManager`s queue. The processQueue thread and active-master thread block waiting for online region servers. when we start a region server, the active-master thread do some operations and init rsgroup balancer.  At the same time, the processQueue thread start to call balancer. If the processQueue thread run faster than active master,  the processQueue thread will throw NPE.  As a result, the procedure not complete and not release hbase:meta region lock forever.
 
 



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