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https://issues.apache.org/jira/browse/HBASE-21344?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16659239#comment-16659239
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Josh Elser commented on HBASE-21344:
------------------------------------
{quote}This is not right, the meta table may on a crashed server, and in RIT
state, if we assign it directly, it may loss some data, since the WAL may not
replayed.
{quote}
Ah, I think I see what you're saying, Allan; I didn't consider that. I was just
thinking about it from the context of the failed AP at the end of an
(otherwise) successful SCP. We don't necessarily know that there isn't an SCP
that needs to happen (and that the SCP wouldn't be re-running when this new
master comes up). I was just thinking about this problem knowing that there was
no SCP to run and assuming IMP was the one who should be assigning meta.
{quote}I suggest we can set hbase.assignment.maximum.attempts to Long.MAX. So
AP will try forever, until we resolve the problem which cause the region can't
assign.
{quote}
{quote}We can't afford that the AP fails(thus SCP roll back) leaving some
region unassigned and we don't know about it
{quote}
I get what you're saying, but I'm not excited about that being our answer,
especially for the seriousness of meta being offline and that we know/expect
such problems to happen.
Thinking out loud... the goal is that IMP is just doing a "normal" assignment
of meta _or_ creating it for the first time. SCP is the one responsible if meta
was on a failed server and getting it back onto the cluster. We can't re-run an
SCP, so we're left with these hosed regions. I want to suggest something that
can make sure we get Regions re-assigned (otherwise, huge user pain-point), but
I need to read some more code to think about that some more :)
Thanks for your help (and Stack's too). Great to come back to!
> hbase:meta location in ZooKeeper set to OPENING by the procedure which
> eventually failed but precludes Master from assigning it forever
> ---------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-21344
> URL: https://issues.apache.org/jira/browse/HBASE-21344
> Project: HBase
> Issue Type: Bug
> Components: proc-v2
> Reporter: Ankit Singhal
> Assignee: Ankit Singhal
> Priority: Major
> Attachments: HBASE-21344-branch-2.0.patch
>
>
> [~elserj] has already summarized it well.
> 1. hbase:meta was on RS8
> 2. RS8 crashed, SCP was queued for it, meta first
> 3. meta was marked OFFLINE
> 4. meta marked as OPENING on RS3
> 5. Can't actually send the openRegion RPC to RS3 due to the krb ticket issue
> 6. We attempt the openRegion/assignment 10 times, failing each time
> 7. We start rolling back the procedure:
> {code:java}
> 2018-10-08 06:51:24,440 WARN [PEWorker-9] procedure2.ProcedureExecutor:
> Usually this should not happen, we will release the lock before if the
> procedure is finished, even if the holdLock is true, arrive here means we
> have some holes where we do not release the lock. And the releaseLock below
> may fail since the procedure may have already been deleted from the procedure
> store.
> 2018-10-08 06:51:24,543 INFO [PEWorker-9]
> procedure.MasterProcedureScheduler: pid=48, ppid=47,
> state=FAILED:REGION_TRANSITION_QUEUE,
> exception=org.apache.hadoop.hbase.client.RetriesExhaustedException via
> AssignProcedure:org.apache.hadoop.hbase.client.RetriesExhaustedException: Max
> attempts exceeded; AssignProcedure table=hbase:meta, region=1588230740
> checking lock on 1588230740
> {code}
> {code:java}
> 2018-10-08 06:51:30,957 ERROR [PEWorker-9] procedure2.ProcedureExecutor:
> CODE-BUG: Uncaught runtime exception for pid=47,
> state=FAILED:SERVER_CRASH_ASSIGN_META, locked=true,
> exception=org.apache.hadoop.hbase.client.RetriesExhaustedException via
> AssignProcedure:org.apache.hadoop.hbase.client.RetriesExhaustedException: Max
> attempts exceeded; ServerCrashProcedure
> server=<ip-address>,16020,1538974612843, splitWal=true, meta=true
> java.lang.UnsupportedOperationException: unhandled
> state=SERVER_CRASH_GET_REGIONS
> at
> org.apache.hadoop.hbase.master.procedure.ServerCrashProcedure.rollbackState(ServerCrashProcedure.java:254)
> at
> org.apache.hadoop.hbase.master.procedure.ServerCrashProcedure.rollbackState(ServerCrashProcedure.java:58)
> at
> org.apache.hadoop.hbase.procedure2.StateMachineProcedure.rollback(StateMachineProcedure.java:203)
> at
> org.apache.hadoop.hbase.procedure2.Procedure.doRollback(Procedure.java:960)
> at
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor.executeRollback(ProcedureExecutor.java:1577)
> at
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor.executeRollback(ProcedureExecutor.java:1539)
> at
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor.executeProcedure(ProcedureExecutor.java:1418)
> at
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor.access$900(ProcedureExecutor.java:75)
> at
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor$WorkerThread.run(ProcedureExecutor.java:1981)
> {code}
> {code:java}
> { DEBUG [PEWorker-2] client.RpcRetryingCallerImpl: Call exception, tries=7,
> retries=7, started=8168 ms ago, cancelled=false, msg=Meta region is in state
> OPENING, details=row 'backup:system' on table 'hbase:meta' at
> region=hbase:meta,,1.1588230740, hostname=<hostname>, seqNum=-1,
> exception=java.io.IOException: Meta region is in state OPENING
> at
> org.apache.hadoop.hbase.client.ZKAsyncRegistry.lambda$null$1(ZKAsyncRegistry.java:154)
> at
> java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:760)
> at
> java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:736)
> at
> java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474)
> at
> java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:1962)
> at
> org.apache.hadoop.hbase.client.ZKAsyncRegistry.lambda$getAndConvert$0(ZKAsyncRegistry.java:77)
> at
> java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:760)
> at
> java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:736)
> at
> java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474)
> at
> java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:1962)
> at
> org.apache.hadoop.hbase.zookeeper.ReadOnlyZKClient$ZKTask$1.exec(ReadOnlyZKClient.java:165)
> at
> org.apache.hadoop.hbase.zookeeper.ReadOnlyZKClient.run(ReadOnlyZKClient.java:323)
> at java.lang.Thread.run(Thread.java:748)
> {code}
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