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From "Enis Soztutar (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-13605) RegionStates should not keep its list of dead servers
Date Fri, 12 Jun 2015 01:54:01 GMT

     [ https://issues.apache.org/jira/browse/HBASE-13605?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Enis Soztutar updated HBASE-13605:
    Attachment: hbase-13605_v3-branch-1.1.patch

We have discovered an issue with the v1 patch which gets surfaced after applying the patch.
It is due to this logic: 
In AM: 
      for (ServerName serverName: deadServers) {
        if (!serverManager.isServerDead(serverName)) {
          serverManager.expireServer(serverName); // Let SSH do region re-assign

Notice that we are expiring the server IF it is NOT dead. Seems weird, right? I assume this
was added because to not trigger SSH twice. 

The v1 patch changes {{serverManager.isServerDead}} so that if a new server is registered
in the online servers, the old server IS considered dead: 

  public synchronized boolean isServerDead(ServerName serverName) {
    if (serverName == null || deadservers.isDeadServer(serverName)
        || queuedDeadServers.contains(serverName)
        || requeuedDeadServers.containsKey(serverName)) {
      return true;

    // we are not acquiring the lock
    ServerName onlineServer = findServerWithSameHostnamePortWithLock(serverName);
    if (onlineServer != null && serverName.getStartcode() < onlineServer.getStartcode())
      return true;

In one of our tests, that is exactly what happened. The RS is registered with a new identifier
(thus onlineServers contains the new definition), and because of this SSH for the old guy
was never called. 

v3 patch fixes this condition by breaking the isServerDead() into two parts. Old callers relies
on isServerInDeadList() while the assignment caller will rely on the new semantics.

We have been running tests including ITBLL, ITMTTR, etc with the v1 patch. Seems stable enough.
v3 patch should fix the remaining issues. 


> RegionStates should not keep its list of dead servers
> -----------------------------------------------------
>                 Key: HBASE-13605
>                 URL: https://issues.apache.org/jira/browse/HBASE-13605
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Enis Soztutar
>            Assignee: Enis Soztutar
>            Priority: Critical
>             Fix For: 2.0.0, 1.0.2, 1.1.1
>         Attachments: hbase-13605_v1.patch, hbase-13605_v3-branch-1.1.patch
> As mentioned in https://issues.apache.org/jira/browse/HBASE-9514?focusedCommentId=13769761&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13769761
and HBASE-12844 we should have only 1 source of cluster membership. 
> The list of dead server and RegionStates doing it's own liveliness check (ServerManager.isServerReachable())
has caused an assignment problem again in a test cluster where the region states "thinks"
that the server is dead and SSH will handle the region assignment. However the RS is not dead
at all, living happily, and never gets zk expiry or YouAreDeadException or anything. This
leaves the list of regions unassigned in OFFLINE state. 
> master assigning the region:
> {code}
> 15-04-20 09:02:25,780 DEBUG [AM.ZK.Worker-pool3-t330] master.RegionStates: Onlined 77dddcd50c22e56bfff133c0e1f9165b
on os-amb-r6-us-1429512014-hbase4-6.novalocal,16020,1429520535268 {ENCODED => 77dddcd50c
> {code}
> Master then disabled the table, and unassigned the region:
> {code}
> 2015-04-20 09:02:27,158 WARN  [ProcedureExecutorThread-1] zookeeper.ZKTableStateManager:
Moving table loadtest_d1 state from DISABLING to DISABLING
>  Starting unassign of loadtest_d1,,1429520544378.77dddcd50c22e56bfff133c0e1f9165b. (offlining),
current state: {77dddcd50c22e56bfff133c0e1f9165b state=OPEN, ts=1429520545780,   server=os-amb-r6-us-1429512014-hbase4-6.novalocal,16020,1429520535268}
> bleProcedure$BulkDisabler-0] master.AssignmentManager: Sent CLOSE to os-amb-r6-us-1429512014-hbase4-6.novalocal,16020,1429520535268
for region loadtest_d1,,1429520544378.77dddcd50c22e56bfff133c0e1f9165b.
> 2015-04-20 09:02:27,414 INFO  [AM.ZK.Worker-pool3-t316] master.RegionStates: Offlined
77dddcd50c22e56bfff133c0e1f9165b from os-amb-r6-us-1429512014-hbase4-6.novalocal,16020,1429520535268
> {code}
> On table re-enable, AM does not assign the region: 
> {code}
> 2015-04-20 09:02:30,415 INFO  [ProcedureExecutorThread-3] balancer.BaseLoadBalancer:
Reassigned 25 regions. 25 retained the pre-restart assignment.ยท
> 2015-04-20 09:02:30,415 INFO  [ProcedureExecutorThread-3] procedure.EnableTableProcedure:
Bulk assigning 25 region(s) across 5 server(s), retainAssignment=true
> l,16000,1429515659726-GeneralBulkAssigner-4] master.RegionStates: Couldn't reach online
server os-amb-r6-us-1429512014-hbase4-6.novalocal,16020,1429520535268
> l,16000,1429515659726-GeneralBulkAssigner-4] master.AssignmentManager: Updating the state
to OFFLINE to allow to be reassigned by SSH
> nmentManager: Skip assigning loadtest_d1,,1429520544378.77dddcd50c22e56bfff133c0e1f9165b.,
it is on a dead but not processed yet server: os-amb-r6-us-1429512014-hbase4-6.novalocal,16020,1429520535268
> {code}

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