RE: [squid-users] I want to purge too many TIME_WAITs immediatelyafter closing HTTP port.

Hello Henrik,
Thank you for replying. The reson why I need to clean TIME_WAIT connection
immediately is that most of the TCP lisnten port become full in the short
period.
My http emulater can send the HTTP packet very fast, so most of squid listen
ports being full in 30 seconds without keep alive, finally http client are
refused to connect from the squid( OS ).

Do you know any other ideas?
Did anyone have same experience ?

Thanks a lot,

Seiji Kobayashi

-----Original Message-----
From: Henrik Nordstrom [mailto:henrik@henriknordstrom.net]
Sent: Tuesday, February 26, 2008 5:11 AM
To: S.KOBAYASHI
Cc: 'Squid Users'
Subject: Re: [squid-users] I want to purge too many TIME_WAITs
immediatelyafter closing HTTP port.

mån 2008-02-25 klockan 17:59 +0900 skrev S.KOBAYASHI:
> Hello there,
>
> I have a bit problem while majoring the squid performance now.
> There are many TIME_WAIT connections left on the squid port by using high
> performance http client machine, and then the next connection can not
> connect the squid. The client machine has capability to send up to 10,000
> req/s.

Why do you consider the TIME_WAIT as such to be a problem? There is no
significant problem to have some hundreds of thousand TIME_WAIT sockets
on a server port. They only consume a little bit of memory each (some
hundreds bytes).

> I tried to change Linux machine's some parameters as bellow.
>
> sysctl -w net.ipv4.tcp_tw_recycle=1

This often have a negative impact.

> sysctl -w net.ipv4.tcp_max_tw_buckets=50000

This will reduce the number of TIME_WAIT sockets to at most 50000, but
will also make the TCP/IP stack no longer conform to specifications and
bad things may happen to legitime traffic from this.

> sysctl -w net.ipv4.tcp_fin_timeout=1

Having this too low may cause a little problem to clients accessing
certain sites incompatible with persistent connections. May result in
connections hanging and never completing in the view of the client.

> Does anyone know how to purge the TIME_WAIT connections immediately?

You do not want to do that. Proper TCP/IP depends on TIME_WAIT.

> The machine running the squid has 16GB memory, the fastest CPU and running
> on 64 bit mode.

So I don't think you need to worry at all about the sockets when they
have reached the TIME_WAIT state.

Regards
Henrik
Received on Mon Feb 25 2008 - 16:54:08 MST