[jira] [Created] (HBASE-14498) Master stuck in infinite loop when all Zookeeper servers are unreachable.

["Y. SREENIVASULU REDDY (JIRA)" <ji...@apache.org>]

Y. SREENIVASULU REDDY created HBASE-14498:
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             Summary: Master stuck in infinite loop when all Zookeeper servers are unreachable.
                 Key: HBASE-14498
                 URL: https://issues.apache.org/jira/browse/HBASE-14498
             Project: HBase
          Issue Type: Bug
          Components: master
    Affects Versions: 1.0.1
            Reporter: Y. SREENIVASULU REDDY
            Priority: Blocker


We met a weird scenario in our production environment.
In a HA cluster,
> Active Master (HM1) is not able to connect to any Zookeeper server (due to N/w breakdown on master machine network with Zookeeper servers).
{code}
2015-09-26 15:24:47,508 INFO [HM1-Host:16000.activeMasterManager-SendThread(ZK-Host:2181)] zookeeper.ClientCnxn: Client session timed out, have not heard from server in 33463ms for sessionid 0x104576b8dda0002, closing socket connection and attempting reconnect
2015-09-26 15:24:47,877 INFO [HM1-Host:16000.activeMasterManager-SendThread(ZK-Host1:2181)] client.FourLetterWordMain: connecting to ZK-Host1 2181
2015-09-26 15:24:48,236 INFO [main-SendThread(ZK-Host1:2181)] client.FourLetterWordMain: connecting to ZK-Host1 2181
2015-09-26 15:24:49,879 WARN [HM1-Host:16000.activeMasterManager-SendThread(ZK-Host1:2181)] zookeeper.ClientCnxn: Can not get the principle name from server ZK-Host1
2015-09-26 15:24:49,879 INFO [HM1-Host:16000.activeMasterManager-SendThread(ZK-Host1:2181)] zookeeper.ClientCnxn: Opening socket connection to server ZK-Host1/ZK-IP1:2181. Will not attempt to authenticate using SASL (unknown error)
2015-09-26 15:24:50,238 WARN [main-SendThread(ZK-Host1:2181)] zookeeper.ClientCnxn: Can not get the principle name from server ZK-Host1
2015-09-26 15:24:50,238 INFO [main-SendThread(ZK-Host1:2181)] zookeeper.ClientCnxn: Opening socket connection to server ZK-Host1/ZK-Host1:2181. Will not attempt to authenticate using SASL (unknown error)
2015-09-26 15:25:17,470 INFO [main-SendThread(ZK-Host1:2181)] zookeeper.ClientCnxn: Client session timed out, have not heard from server in 30023ms for sessionid 0x2045762cc710006, closing socket connection and attempting reconnect
2015-09-26 15:25:17,571 WARN [master/HM1-Host/HM1-IP:16000] zookeeper.RecoverableZooKeeper: Possibly transient ZooKeeper, quorum=ZK-Host:2181,ZK-Host1:2181,ZK-Host2:2181, exception=org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /hbase/master
2015-09-26 15:25:17,872 INFO [main-SendThread(ZK-Host:2181)] client.FourLetterWordMain: connecting to ZK-Host 2181
2015-09-26 15:25:19,874 WARN [main-SendThread(ZK-Host:2181)] zookeeper.ClientCnxn: Can not get the principle name from server ZK-Host
2015-09-26 15:25:19,874 INFO [main-SendThread(ZK-Host:2181)] zookeeper.ClientCnxn: Opening socket connection to server ZK-Host/ZK-IP:2181. Will not attempt to authenticate using SASL (unknown error)
{code}

> Since HM1 was not able to connect to any ZK, so session timeout didnt happen at Zookeeper server side and HM1 didnt abort.

> On Zookeeper session timeout standby master (HM2) registered himself as an active master. 
> HM2 is keep on waiting for region server to report him as part of active master intialization.
{noformat} 
2015-09-26 15:24:44,928 | INFO | HM2-Host:21300.activeMasterManager | Waiting for region servers count to settle; currently checked in 0, slept for 0 ms, expecting minimum of 1, maximum of 2147483647, timeout of 4500 ms, interval of 1500 ms. | org.apache.hadoop.hbase.master.ServerManager.waitForRegionServers(ServerManager.java:1011)
---
---
2015-09-26 15:32:50,841 | INFO | HM2-Host:21300.activeMasterManager | Waiting for region servers count to settle; currently checked in 0, slept for 483913 ms, expecting minimum of 1, maximum of 2147483647, timeout of 4500 ms, interval of 1500 ms. | org.apache.hadoop.hbase.master.ServerManager.waitForRegionServers(ServerManager.java:1011)
{noformat}

> At other end, region servers are reporting to HM1 on 3 sec interval. Here region server retrieve master location from zookeeper only when they couldn't connect to Master (ServiceException).
Region Server will not report HM2 as per current design until unless HM1 abort,so HM2 will exit(InitializationMonitor) and again wait for region servers in loop.



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