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From "Rong-en Fan" <gra...@gmail.com>
Subject Re: re-balance regions based on avgLoad
Date Sun, 08 Jun 2008 09:34:59 GMT
On Sun, Jun 8, 2008 at 5:26 PM, Rong-en Fan <grafan@gmail.com> wrote:
> 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, it should be 615.

>
> 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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