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 <cove...@gmail.com> wrote:

> Backend connections sit in close_wait until Apache tries to reuse
> them. What problem does it cause?
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