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From "Ted Dunning" <ted.dunn...@gmail.com>
Subject Re: Lots of connections from datanodes in TIME_WAIT
Date Wed, 17 Sep 2008 06:42:05 GMT
When it needs a socket and all are in TIME_WAIT, it basically switches to
FIFO strategy instead of waiting forever.

This is critical when using Linux as a load balancer on large web
applications.  You can easily have 100,000 unique connections in a few
minutes.

On Tue, Sep 16, 2008 at 6:09 PM, Raghu Angadi <rangadi@yahoo-inc.com> wrote:

> Ted Dunning wrote:
>
>> There are OS settings, but modern Linux kernels automatically adjust the
>> setting if necessary.
>>
>
> That is good. Do you know what it does?
>
> When I was replying to the original mail thought Linux might actively
> remove connections from this state if the number of such connections reaches
> a limit.. otherwise it could be a pretty bad scalability limit for some
> applications.
>
> Raghu.
>
>
>  On Tue, Sep 16, 2008 at 8:38 AM, Raghu Angadi <rangadi@yahoo-inc.com>
>> wrote:
>>
>>  Thats ok. Its a normal TCP state for the closed connections. There is
>>> probably some OS level setting to reduce the amount of time these
>>> connections stay in this state.
>>>
>>> It does not indicate a bug in application.
>>>
>>> Raghu.
>>>
>>>
>>> damien.cooke@internode.on.net wrote:
>>>
>>>  Hi all,
>>>> We have a 10 node cluster and I noticed that there are a large number of
>>>> connections in TIME_WAIT status,  over 400 to more precise.  Does anyone
>>>> else see so many unclosed connections or have I done something wrong in
>>>> my
>>>> config.  It appears to be coming from and going to other datanodes.
>>>> I was running the javasort benchmark when I noticed it.  Any advice
>>>> appreciated.
>>>>
>>>> Regards
>>>> Damien
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>
>>
>


-- 
ted

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