Master does not respect generation stamps, may result in meta getting
permanently offlined
------------------------------------------------------------------------------------------
Key: HBASE-2413
URL: https://issues.apache.org/jira/browse/HBASE-2413
Project: Hadoop HBase
Issue Type: Bug
Components: master
Affects Versions: 0.20.3
Reporter: Karthik Ranganathan
This happens if the RS is restarted before the zk node expires. The sequence is
as follows:
1. RS1 dies - lets say its server string was HOST1:PORT1:TS1
2. In a few seconds RS1 is restarted, it comes up as HOST1:PORT1:TS2 (TS2 is
more recent than TS1)
3. Master gets a start up message from RS1 with the server name as
HOST1:PORT1:TS2
4. Master adds this as a new RS, tries to red
**** The master does not use the generation stamps to detect that RS1 has
already restarted.
**** Also, if RS1 contained meta, master would try to go to HOST1:PORT1:TS1. It
would end up talking to HOST1:PORT1:TS2, which spews a bunch of not serving
region exceptions.
5. zk node expires for HOST1:PORT1:TS1
6. Master tries to process shutdown for HOST1:PORT1:TS1 - this probably
interferes with HOST1:PORT1:TS2 and ends up somehow removing the reassign meta
in the master's queue.
**** Meta never comes online and master continues logging the following
exception indefinitely:
2010-04-06 11:02:23,988 DEBUG org.apache.hadoop.hbase.master.HMaster:
Processing todo: ProcessRegionClose of test1,7094000000,1270220428234, false,
reassign: true
2010-04-06 11:02:23,988 DEBUG
org.apache.hadoop.hbase.master.ProcessRegionClose$1: Exception in
RetryableMetaOperation:
java.lang.NullPointerException
at
org.apache.hadoop.hbase.master.RetryableMetaOperation.doWithRetries(RetryableMetaOperation.java:64)
at
org.apache.hadoop.hbase.master.ProcessRegionClose.process(ProcessRegionClose.java:63)
at
org.apache.hadoop.hbase.master.HMaster.processToDoQueue(HMaster.java:494)
at org.apache.hadoop.hbase.master.HMaster.run(HMaster.java:429)
Fix is to have master recognize the RS1 restart before the zk node expires and
handle it right away. There should only be one entry for each HOST:PORT - the
one with the latest TS.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
