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https://issues.apache.org/jira/browse/HBASE-6587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13435805#comment-13435805
]
chunhui shen commented on HBASE-6587:
-------------------------------------
@ram
{code}
2012-08-14 20:42:54,367 DEBUG org.apache.hadoop.hbase.master.AssignmentManager:
Unable to determine a plan to assign .META.,,1.1028785192 state=OFFLINE, ts=1
344948174367, server=null
{code}
After the above log, TimeoutMonitor set allRegionServersOffline true
{code}2012-08-14 20:44:31,640 DEBUG
org.apache.hadoop.hbase.master.AssignmentManager: No previous transition plan
was found (or we are ignoring an existing plan) for writete
st,VHXYHJN0BL48HMR4DI1L,1344925649429.277b9b6df6de2b9be1353b4fa25f4222. so
generated a random one;
hri=writetest,VHXYHJN0BL48HMR4DI1L,1344925649429.277b9b6df6de2b9be13
53b4fa25f4222., src=, dest=dw92.kgb.sqa.cm4,60020,1344948267642; 1 (online=1,
available=1) available {code}
At the 2012-08-14 20:44:31, one server is onlined now, and region
277b9b6df6de2b9be1353b4fa25f4222 is sucessfully assigned.
However, at that time TimeoutMonitor, in th chore(), it would act on time out
because the if block {
code}if (this.allRegionServersOffline && !allRSsOffline){code} return true;
So we see the following log
{code}2012-08-14 20:44:32,518 INFO
org.apache.hadoop.hbase.master.AssignmentManager: Regions in transition timed
out: writetest,VHXYHJN0BL48HMR4DI1L,1344925649429.277b9b6df
6de2b9be1353b4fa25f4222. state=OPENING, ts=1344948272279,
server=dw92.kgb.sqa.cm4,60020,1344948267642
2012-08-14 20:44:32,518 INFO org.apache.hadoop.hbase.master.AssignmentManager:
Region has been OPENING for too long, reassigning
region=writetest,VHXYHJN0BL48HMR4DI1L,
1344925649429.277b9b6df6de2b9be1353b4fa25f4222.
{code}
The region is assigned at the time 2012-08-14 20:44:31, but is timed out by
TimeoutMonitor at the time 2012-08-14 20:44:32.
It cause the collision by two assign thread,
And the result is that the region is onlined after 30mins.
> Region would be assigned twice in the case of all RS offline
> ------------------------------------------------------------
>
> Key: HBASE-6587
> URL: https://issues.apache.org/jira/browse/HBASE-6587
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.94.1
> Reporter: chunhui shen
> Assignee: chunhui shen
> Fix For: 0.96.0
>
> Attachments: 6587.patch, HBASE-6587.patch
>
>
> In the TimeoutMonitor, we would act on time out for the regions if
> (this.allRegionServersOffline && !noRSAvailable)
> The code is as the following:
> {code}
> if (regionState.getStamp() + timeout <= now ||
> (this.allRegionServersOffline && !noRSAvailable)) {
> //decide on action upon timeout or, if some RSs just came back
> online, we can start the
> // the assignment
> actOnTimeOut(regionState);
> }
> {code}
> But we found it exists a bug that it would act on time out for the region
> which was assigned just now , and cause assigning the region twice.
> Master log for the region 277b9b6df6de2b9be1353b4fa25f4222:
> {code}
> 2012-08-14 20:42:54,367 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Unable to determine a plan
> to assign .META.,,1.1028785192 state=OFFLINE, ts=1
> 344948174367, server=null
> 2012-08-14 20:44:31,640 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: No previous transition plan
> was found (or we are ignoring an existing plan) for writete
> st,VHXYHJN0BL48HMR4DI1L,1344925649429.277b9b6df6de2b9be1353b4fa25f4222. so
> generated a random one;
> hri=writetest,VHXYHJN0BL48HMR4DI1L,1344925649429.277b9b6df6de2b9be13
> 53b4fa25f4222., src=, dest=dw92.kgb.sqa.cm4,60020,1344948267642; 1 (online=1,
> available=1) available servers
> 2012-08-14 20:44:31,640 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> master:60000-0x438f53bbf9b0acd Creating (or updating) unassigned node for
> 277b9b6df6de2b9be13
> 53b4fa25f4222 with OFFLINE state
> 2012-08-14 20:44:31,643 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Assigning region
> writetest,VHXYHJN0BL48HMR4DI1L,1344925649429.277b9b6df6de2b9be1353b4fa
> 25f4222. to dw92.kgb.sqa.cm4,60020,1344948267642
> 2012-08-14 20:44:32,291 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Handling
> transition=RS_ZK_REGION_OPENING, server=dw92.kgb.sqa.cm4,60020,1344948267642,
> region=277b9b6df6de2b9be1353b4fa25f4222
> // 异常的超时
> 2012-08-14 20:44:32,518 INFO
> org.apache.hadoop.hbase.master.AssignmentManager: Regions in transition timed
> out: writetest,VHXYHJN0BL48HMR4DI1L,1344925649429.277b9b6df
> 6de2b9be1353b4fa25f4222. state=OPENING, ts=1344948272279,
> server=dw92.kgb.sqa.cm4,60020,1344948267642
> 2012-08-14 20:44:32,518 INFO
> org.apache.hadoop.hbase.master.AssignmentManager: Region has been OPENING for
> too long, reassigning region=writetest,VHXYHJN0BL48HMR4DI1L,
> 1344925649429.277b9b6df6de2b9be1353b4fa25f4222.
> {code}
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