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https://issues.apache.org/jira/browse/HBASE-7932?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13650564#comment-13650564
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stack commented on HBASE-7932:
------------------------------
I was thinking that when balance is called, your new balancer should have
nothing to do right? But I suppose it has to read .META. per region to balance
and then assign to one of the favored node locations (in a manner that helps w/
general cluster balancer? Or teach the stochastic balancer to pay attention to
these .META. table additions?)
Does access to rackToRegionServerMap need to be synchronized since you are
checking, then calculating before putting back an item to two different maps
(Or maybe access will be single threaded when balancing?)?
Is this.regionServerToRackMap.keySet().size(); different from
this.regionServerToRackMap.size()?
Instead of
+ if (serverSize < FAVORED_NODES_NUM)
+ return false;
+ return true;
maybe do....
return serverSize >= FAVORED_NODES_NUM;
What happens if one rack only? i.e. 20 servers? Hmmm... looks like things
will work fine. We'll just spread the regions over the rack.
On assign, you are just trying to spread the regions. I suppose it would make
some sense to consider how loaded a regionserver already is before choosing it?
How many regions it is carrying?
So what if it is cluster startup and there 10k regions to assign. Are we
inlining this update of .META. one region at a time as we process the 10k
regions? This could slow assign way down adding at least a second per region?
I though you were doing similar on open of a region doing read of favored nodes
but it looks like this read-before-we-open has been in place w/ a while now,
added by hbase-5094 in 0.92. Doing this latter, piggybacking on the read that
is already happening, makes it so you do not have to complicate the open
passing favored nodes from master to regionserver? (Thats good).
If .META. already has been marked with favored nodes, we do not seem to be
taking notice only overwriting whatever is there on each assign? Do I have
that wrong?
The first time you do this:
+ favoredServerList = getFavoredNodesList(favoredNodes);
I do not see how it is added to updateRegionFavoredNodesMapping.... am I
reading it wrong?
favoredNodes in .META. need to be pb'd (then you can serialize them as
ServerNames and not have to do that parse of a String).
Why InetSocketAddress saving favored nodes? I see you are doing unresolve
which helps but why use it at all? Can you not use the hostname/port you got
out of meta written by the master?
Would suggest figuring how to add unit tests for methods of
FavoredNodeLoadBalancer since they are doing a bunch of math? Maybe make them
static so easy to conjure inputs and test the method outputs.
I think this approach much cleaner; better packaging of all that is going on.
> Do the necessary plumbing for the region locations in META table and send the
> info to the RegionServers
> -------------------------------------------------------------------------------------------------------
>
> Key: HBASE-7932
> URL: https://issues.apache.org/jira/browse/HBASE-7932
> Project: HBase
> Issue Type: Sub-task
> Reporter: Devaraj Das
> Assignee: Devaraj Das
> Priority: Critical
> Fix For: 0.95.1
>
> Attachments: 7932-1.patch, 7932-3.patch, 7932-8.1.patch,
> 7932-8.patch, 7932-simple-2.patch, 7932-wip-2.patch, 7932-wip-3.patch,
> 7932-wip-4.patch, 7932-wip.patch
>
>
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