Mike, thank You for your answer.
I'm using Linux, and I don't care about Windows.
Actually, my problem is not related to the web server, but it's related to
the client.
My client side CLOSE_WAIT sockets persist for a very long time: I left my
Java application running several hours (about one night) and in the next
morning I found the same number of CLOSE_WAIT socket of the evening before,
and my Java app gave exceptions for the whole night about the fact that
there was no way to get another socket from the OS.
This makes me think that most likely it's not a problem related to a timeout
parameter, but something related to an unreleased socket, somewhere.
>From netstat manpage you can read:
CLOSE_WAIT: The socket connection has been closed by the remote peer,
and the system is waiting for the local application to close its half
of
the connection.
As you see, this means that the OS is not automatically closing the socket
until the process who requested the socket doesn't relese it. Perhaps, the
reason is that from the OS's point of view, the process may be pooling its
sockets someway, so why release its sockets?
I think the timeout you suggest me to use is related to the time waited by
the OS before freeing the socket when the owner process does not exist any
more (ie: killing -9 the process makes him not release sockets. So after a
timeout the OS frees the sockets owned by that process) or the time waited
by the OS before releasing sockets in TIME_WAIT state. From man netstat:
TIME_WAIT: The socket connection has been closed by the local
application, the remote peer has closed its half of the connection, and
the system is waiting to be sure that the remote peer received the last
acknowledgement.
I've read about the fact that this parameter was once called
tcp_close_wait_interval, but the name was not correct and brought many
people in confusion, so it was renamed tcp_time_wait_interval. So I don't
think it's related to the CLOSE_WAIT socket state.
Is it correct?
Anyway, Monday I'll try to reduce significantly this parameter, then I'll
let you know.
Any more idea?
In the meantime, thank you Mike.
Bye,
Matteo.
> -----Messaggio originale-----
> Da: Mike Burati [mailto:[EMAIL PROTECTED]
> Inviato: venerd́ 31 ottobre 2003 20.01
> A: '[EMAIL PROTECTED]'
> Oggetto: RE: Too many CLOSE_WAIT socket connections
>
>
> Both Unix and Windows appear to have TCP Time Wait timeouts
> set too high by default (about 5 minutes) where the OS leaves
> closed sockets in the CLOSE_WAIT state queuing up
> (which can
> make it real easy to hit the maxfd limit on a heavily loaded
> web server).
> I believe the value is something like tcp_time_wait_interval
> (kernel param) on Unix systems, and I can't remember what the
> Windows Registry key is for the equivalent setting, but it's
> name is similar.
> Set those smaller (eg, 30 or 60 seconds) and you should avoid
> the problem you're seeing.
