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https://issues.apache.org/jira/browse/HBASE-2312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12896680#action_12896680
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stack commented on HBASE-2312:
------------------------------
When I apply this patch to trunk, unit tests hang. Are we missing something
from our hadoop Nicolas? We have 0.20.3-append-r964955-1240 committed to trunk
(Thats the svn revision and patch 1240 applied).
I see for example that the TestZookeeper is stuck doing this:
{code}
2010-08-09 12:45:23,964 WARN [IPC Server handler 6 on 62023]
namenode.FSNamesystem(1166): DIR* NameSystem.startFile: failed to create file
/user/Stack/.logs/h135.sfo.stumble.net,62051,1281382952055-splitting/10.10.1.135%3A62051.1281382952241
for DFSClient_-1591590456 on client 127.0.0.1, because this file is already
being created by DFSClient_hb_m_10.10.1.135:62037 on 127.0.0.1
2010-08-09 12:45:23,965 WARN [master] util.FSUtils(631): Waited 151520ms for
lease recovery on
hdfs://localhost:62023/user/Stack/.logs/h135.sfo.stumble.net,62051,1281382952055-splitting/10.10.1.135%3A62051.1281382952241:org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException:
failed to create file
/user/Stack/.logs/h135.sfo.stumble.net,62051,1281382952055-splitting/10.10.1.135%3A62051.1281382952241
for DFSClient_-1591590456 on client 127.0.0.1, because this file is already
being created by DFSClient_hb_m_10.10.1.135:62037 on 127.0.0.1
at
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInternal(FSNamesystem.java:1093)
at
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.appendFile(FSNamesystem.java:1181)
at
org.apache.hadoop.hdfs.server.namenode.NameNode.append(NameNode.java:396)
at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:508)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:961)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:957)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:955)
{code}
This test passes if I do not have /HBASE-2312-2.patch in place.
> Possible data loss when RS goes into GC pause while rolling HLog
> ----------------------------------------------------------------
>
> Key: HBASE-2312
> URL: https://issues.apache.org/jira/browse/HBASE-2312
> Project: HBase
> Issue Type: Bug
> Components: master, regionserver
> Affects Versions: 0.20.3
> Reporter: Karthik Ranganathan
> Assignee: Nicolas Spiegelberg
> Fix For: 0.90.0
>
>
> There is a very corner case when bad things could happen(ie data loss):
> 1) RS #1 is going to roll its HLog - not yet created the new one, old one
> will get no more writes
> 2) RS #1 enters GC Pause of Death
> 3) Master lists HLog files of RS#1 that is has to split as RS#1 is dead,
> starts splitting
> 4) RS #1 wakes up, created the new HLog (previous one was rolled) and
> appends an edit - which is lost
> The following seems like a possible solution:
> 1) Master detects RS#1 is dead
> 2) The master renames the /hbase/.logs/<regionserver name> directory to
> something else (say /hbase/.logs/<regionserver name>-dead)
> 3) Add mkdir support (as opposed to mkdirs) to HDFS - so that a file
> create fails if the directory doesn't exist. Dhruba tells me this is very
> doable.
> 4) RS#1 comes back up and is not able create the new hlog. It restarts
> itself.
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