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From "Rong-en Fan" <gra...@gmail.com>
Subject Re: re-balance regions based on avgLoad
Date Sun, 08 Jun 2008 09:26:10 GMT
On Sun, Jun 8, 2008 at 11:19 AM, Bryan Duxbury <bryan@rapleaf.com> wrote:
> We have an issue open tracking the fact that the rebalancing code has a
> tendency to oscillate. I haven't had the time to look at it for a while. It
> definitely needs some attention.
>
> The point of checking whether the avgLoad is > 2.0 is to ensure that no
> rebalancing occurs before there are more regions than there are servers. It
> doesn't do anything in that case.

Aha, yes.... I mis-read the code...  I will watch HBASE-71.

Sorry for the noise.

Regards,
Rong-En Fan

>
> -Bryan
>
> On Jun 7, 2008, at 7:55 PM, Rong-en Fan wrote:
>
>> On Sun, Jun 8, 2008 at 10:53 AM, Rong-en Fan <grafan@gmail.com> wrote:
>>>
>>> I'm playing with latest hbase trunk and noticed there is a
>>> region close-then-assign looping.
>>>
>>> I have 3 region servers and total regions are about 108, and
>>> the avgLoad is 36.0, then this code in RegionManager.java:
>>>
>>>     if (regionsToAssign.size() == 0) {
>>>       // There are no regions waiting to be assigned. This is an
>>> opportunity
>>>       // for us to check if this server is overloaded.
>>>       double avgLoad = master.serverManager.getAverageLoad();
>>>       if (avgLoad > 2.0 && thisServersLoad.getNumberOfRegions() >
>>> avgLoad) {
>>>
>>> If I understand correctly, when there is no outstanding unassigned
>>> regions, then RegionManager tries to check whether a region server
>>> is overloaded by the # of loaded regions on this region server.
>>> Then, it seems to me that avgLoad > 2.0 is quite unrealistic under
>>> current calculation of "avgLoad".
>>
>> Forget to mention, under my situation, all 3 boxes are kicking regions
>> among them as all loaded regions > avgLoad... even after assign
>> some to others.
>>
>> Regards,
>> Rong-En Fan
>>
>>> Isn't the better way to consider system load or based on # of loaded
>>> regions and # of requests?
>>>
>>> Thanks,
>>> Rong-En Fan
>>>
>
>

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