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From Bongjae Chang <>
Subject Re: [users@httpd] CLOSE_WAIT problem
Date Fri, 25 May 2012 02:01:16 GMT
Hi Igor,

Right. Maybe I can eliminate them as os params.

But, I agree the following contents("It is not a TCP tuning issue") about

But, thank you again for your information!


Bongjae Chang

From:  Igor Cicimov <>
Reply-To:  <>
Date:  Friday, May 25, 2012 7:32 AM
To:  <>
Subject:  Re: [users@httpd] CLOSE_WAIT problem

You can reduce the time on OS level if you want by tuning the tcp stack.
On May 25, 2012 3:00 AM, "Bongjae Chang" <> wrote:
> Hi Eric,
> Thank you for quick reply.
> You mean if Apache picks up the closed conn and tries to do some I/O
> operations like writing, Apache will failover the conn(with closing the conn
> and creating/reusing new conn). So CLOSE_WAIT may be normal in this case,
> right?
> IMHO, as soon as connections are closed from backend, if Apache can detect
> closed connections of backend and close them explicitly, CLOSE_WAITs can
> disappear as soon as possible before Apache tries to reuse them.
> Honestly, I didn't know the CLOSE_WAIT conn would be able to be reused because
> new connections always established in my test(I shut down the old backend and
> rebooted the new backend, then both ESTABLISHED and CLOSE_WAIT existed).
> And I read the default max number which will be allowed to backend is
> ThreadsPerChild directive and users can set the max or ThreadsPerChild to be a
> big number. Then, I think many CLOSE_WAITs can be piled up. It's a waste of
> FDs.
> Actually, I was afraid of the following situation.
> 1. Apache has many backend connections(i.g 8080 backend port)
> 2. Backend server should be replaced for maintenace
> 3. So Apache connects new backend server(i.g 9090 backend port) dynamically
> without reboot and old backend server will be shut down
> 4. Then all old backend connections(i.g 8080 backend port) will become to be
> CLOSE_WAIT state for long time.
> At this case, I would like to know Apache can also clean up 8080 ports of
> CLOSE_WAIT state.
> Thanks in advance!
> Regards,
> Bongjae Chang
> On Thu, May 24, 2012 at 7:25 PM, Eric Covener <> wrote:
>> Backend connections sit in close_wait until Apache tries to reuse
>> them. What problem does it cause?
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