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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-18215) some advises about refactoring of rsgroup
Date Mon, 19 Jun 2017 17:41:00 GMT

    [ https://issues.apache.org/jira/browse/HBASE-18215?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16054434#comment-16054434
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stack commented on HBASE-18215:
-------------------------------

bq. Putting it in HDFS was something we thought about before but one reviewer did not like
it and suggested we use a table. That was sometime ago will have to dig it up.

The justification you give above [~toffer] -- "...but you are pushing complexity to the user
in the way of managing the file: persistence in case of failure, dealing with concurrent updates,
etc. .." -- is pretty good I'd say.

bq. Won't this still leak rsgroup balancer into core code? We could create the same jamon
file but with rsgroup info in hbase-rsgroup and overwrite the hbase-server's somehow.

Was thinking that having webserver last, it would have all dependencies in CLASSPATH; could
do stuff too like pick up pages from well-known locations and serve them up (Main point is
+1 on resgroup info in the web ui... how we do it, needs a bit of thought/work).

> some advises about refactoring of rsgroup
> -----------------------------------------
>
>                 Key: HBASE-18215
>                 URL: https://issues.apache.org/jira/browse/HBASE-18215
>             Project: HBase
>          Issue Type: Improvement
>          Components: Balancer
>            Reporter: chenxu
>         Attachments: HBASE-18215-1.2.4-v1.patch
>
>
> recently we have Integrated rsgroup into our cluster,  after Integrated, found some refactoring
points. maybe the points were not right, but i think there is a need to share with you guys.
> # when hbase.balancer.tablesOnMaster configured, RSGroupBasedLoadBalancer should consider
masterServer assignment first in balanceCluster, roundRobinAssignment, retainAssignment and
randomAssignment
>   do the same thing as BaseLoadBalancer
> # why not use a local file as the persistence layer instead of rsgroup table. 
> in our implementation, we first modify the local rsgroup file, then load the group info
into memory, after that execute the balancer command, everything is OK.
> when loading do some sanity check:
> (1) one server can not be owned by multi group
> (2) one table can not be owned by multi group
> (3) if group has table, it must also has servers
> (4) default group must has servers in it
> if sanity check can’t pass, give up the following process.work as this, it can greatly
reduce the complexity of rsgroup implementation, there is no need to wait for the rsgroup
table to be online, and methods like moveServers, moveTables, addRSGroup, removeRSGroup, moveServersAndTables
can be removed from RSGroupAdminService.only a refresh method is need(modify persistence layer
first and refresh the memory)
> # we should add some group informations on master web UI
> to do this, RSGroupBasedLoadBalancer should move to hbase-server module, because MasterStatusTmpl.jamon
depends on it
> # there may be some issues about RSGroupBasedLoadBalancer.roundRobinAssignment
> if two groups both include BOGUS_SERVER_NAME, assignments.putAll will overwrite the previous
data
> # there may be some issues about RSGroupBasedLoadBalancer.randomAssignment
> when the return value is BOGUS_SERVER_NAME, AM can not handle this case. we should return
null value instead of BOGUS_SERVER_NAME.
> # when RSGroupBasedLoadBalancer.balanceCluster execute, groups are balanced one by one,
if there are two many groups, we can do this in parallel.



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