[jira] [Created] (HBASE-21519) Namespace region is never assigned in a HM failover scenario and HM abort always due to init timeout

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

Pankaj Kumar created HBASE-21519:
------------------------------------

             Summary: Namespace region is never assigned in a HM failover scenario and HM abort always due to init timeout
                 Key: HBASE-21519
                 URL: https://issues.apache.org/jira/browse/HBASE-21519
             Project: HBase
          Issue Type: Bug
          Components: master, wal
    Affects Versions: 2.1.1
            Reporter: Pankaj Kumar


In our test env we found that namespace region is never be assigned on HM failover scenario when multiwal feature is enabled,
{noformat}
2018-11-28 01:38:28,085 WARN [master/HM-1:16000:becomeActiveMaster] master.HMaster: hbase:namespace,,1543339859614.31f6d3383af09e18e1e81ca02a93de15. is NOT online; state=\{31f6d3383af09e18e1e81ca02a93de15 state=OPEN, ts=1543340156928, server=RS-2,16020,1543339824397}; ServerCrashProcedures=false. Master startup cannot progress, in holding-pattern until region onlined.
{noformat}
And finally HM abort with following error,
{noformat}
2018-11-28 01:39:16,858 ERROR [ActiveMasterInitializationMonitor-1543338648565] master.HMaster: Master failed to complete initialization after 240000ms. Please consider submitting a bug report including a thread dump of this process.
2018-11-28 01:39:18,980 ERROR [ActiveMasterInitializationMonitor-1543338648565] master.HMaster: Zombie Master exiting. Thread dump to stdout
{noformat}
Stack trace:
{noformat}
Thread 102 (master/HM-1:16000:becomeActiveMaster):
 State: TIMED_WAITING
 Blocked count: 100
 Waited count: 246
 Stack:
 java.lang.Thread.sleep(Native Method)
 org.apache.hadoop.hbase.util.Threads.sleep(Threads.java:148)
 org.apache.hadoop.hbase.master.HMaster.isRegionOnline(HMaster.java:1166)
 org.apache.hadoop.hbase.master.HMaster.waitForNamespaceOnline(HMaster.java:1187)
 org.apache.hadoop.hbase.master.HMaster.finishActiveMasterInitialization(HMaster.java:1044)
 org.apache.hadoop.hbase.master.HMaster.startActiveMasterManager(HMaster.java:2285)
 org.apache.hadoop.hbase.master.HMaster.lambda$run$0(HMaster.java:590)
 org.apache.hadoop.hbase.master.HMaster$$Lambda$40/1078246575.run(Unknown Source)
 java.lang.Thread.run(Thread.java:745)
{noformat}
 

Step to reproduce:
 1) Setup a HBase cluster with 1/2 HM (say HM-1) and 2 RS(say RS-1 & RS-2)
 2) Enable multiwal feature with following configuration setting and start the cluster,
{noformat}
 <property>
 <name>hbase.wal.provider</name>
 <value>multiwal</value>
 </property>

<property>
 <name>hbase.wal.regiongrouping.strategy</name>
 <value>identity</value>
 </property>
{noformat}
3) Make sure meta and namespace regions are assigned on different RS, suppose RS-1 & RS-2 respectively.
 4) Create table 't1' 
 5) Flush the meta table explicitly
 6) Kill the RS-2, so during RS-2 SCP all regions including namespace region will be assigned to RS-1.
 7) Now Kill RS-1 before meta flush happen. Here both RS-2 & RS-1 are shutdown now.
 8) Stop the HM and start RS-1 & RS-2.
 9) Now start the HM.

Meta region is assigned successfully but HM is keep waiting for the namespace region onlline (Master startup cannot progress, in holding-pattern until region onlined) and abort with timeout.

Observation:
 1) After step-3 namespace region was assigned to RS-2 and meta entry was as follows,
{noformat}
 hbase:namespace,,1543339859614.31f6d3383af09e18e1e81ca02a93de15. column=info:server, timestamp=1543339860920, value=RS-2:16020
 hbase:namespace,,1543339859614.31f6d3383af09e18e1e81ca02a93de15. column=info:serverstartcode, timestamp=1543339860920, value=1543339824397
{noformat}
2) After step-6 namespace region was assigned to RS-1 and meta entry was as follows,
{noformat}
 hbase:namespace,,1543339859614.31f6d3383af09e18e1e81ca02a93de15. column=info:server, timestamp=1543339880920, value=RS-1:16020
 hbase:namespace,,1543339859614.31f6d3383af09e18e1e81ca02a93de15. column=info:serverstartcode, timestamp=1543339880920, value=1543339829288
{noformat}
3) After Step-9, meta entry for namespace region was as follows,
{noformat}
 hbase:namespace,,1543339859614.31f6d3383af09e18e1e81ca02a93de15. column=info:server, timestamp=1543339860920, value=RS-2:16020
 hbase:namespace,,1543339859614.31f6d3383af09e18e1e81ca02a93de15. column=info:serverstartcode, timestamp=1543339860920, value=1543339824397
{noformat}
During SCP we do meta log split based on filter,
{noformat}
 /**
 * Specialized method to handle the splitting for meta WAL
 * @param serverNames logs belonging to these servers will be split
 */
 public void splitMetaLog(final Set<ServerName> serverNames) throws IOException {
 splitLog(serverNames, META_FILTER);
 }
{noformat}
So in this case meta log split will be skipped because of multiwal provider.

HBase version is 2.1.1.

I will analyze it further.



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