Jonathan Ben Avraham wrote:
Hi Marc,
The .NET client has a bug that prevents use of persistent MySQL
connections. The application is already cached up the wazoo.
Where would I look in the kernel to see if it is rejecting the
connections as opposed to MySQL? Or is this just unlikely given that
the hardware is fairly robust?
I don't know of a way to get the statistics from the kernel for that,
but maybe this will help:
"The duration that affects the rate at which new connections are
accepted is the time spent on the queue of pending incoming connections.
This duration is equal to the round trip time for the SYN|ACK message
and its ACK response plus the time taken for the client to process the
SYN|ACK message plus the delay for the server to process the ACK and
call *accept()*.
The rate at which new connections can be accepted is equal to the number
of entries which can fit on the listen queue divided by the average
length of time each entry spends on the queue. Therefore, the larger the
queue, the greater the rate at which new connection requests can be
accepted."
http://www.linuxjournal.com/files/linuxjournal.com/linuxjournal/articles/023/2333/2333s2.html
Thanks,
- yba
On Mon, 2 Feb 2009, m...@swiftouch.com wrote:
Date: Mon, 2 Feb 2009 18:28:21 +0200 (IST)
From: m...@swiftouch.com
To: Jonathan Ben Avraham <y...@tkos.co.il>
Cc: Gilad Ben-Yossef <gi...@codefidence.com>, ILUG
<linux-il@cs.huji.ac.il>
Subject: Re: [YBA] TCP connection rate
Hi all
Without delving into the stack behaviour, I would try the
(potentially) cheaper route - is there a possibility of amalgamating
queries to the database, thereby reducing the per second metric? Or -
perish the thought (caveat emptor, I am not acquainted with the app)
- caching replies at the client?
I am not sure the netstat trick can work in this case - both since
(as YBA noted) the connexions are brief and because netstat deals
with connections very late in their lifecycle. I am not sure how
connexions pending on the stack would show up.
M
---MAV
Marc. Volovic
+972-54-467-6764
m...@swiftouch.com
Sent from my iPhone
On Feb 2, 2009, at 5:06 PM, Jonathan Ben Avraham <y...@tkos.co.il> wrote:
Hi Gilad,
Thanks. The problem is that the connections are exceedingly
short-lived. By the time I type in "netstat -na" already 1000 of
them have come and gone.
- yba
On Mon, 2 Feb 2009, Gilad Ben-Yossef wrote:
Date: Mon, 02 Feb 2009 16:29:23 +0200
From: Gilad Ben-Yossef <gi...@codefidence.com>
To: Jonathan Ben Avraham <y...@tkos.co.il>
Cc: ILUG <linux-il@cs.huji.ac.il>
Subject: Re: [YBA] TCP connection rate
Jonathan Ben Avraham wrote:
Dear list members,
What limits the rate that the Linux kernel TCP stack can accept
new connections? How is that rate related to the rate that the
application listening on a port can handle the connections? That
is, if I try to connect and get ECONNREFUSED is there a way for me
to know if I got it because the kernel could not handle the
connection rate or if I got it because I had more connection
attempts than the backlog parameter of my listen() call? In other
words, do I need to tune the kernel or the application (MySQL) for
the desired high connection rate and how would I know?
Just check what the value of the backlog parameter is and then use
netstat to watch the application connections when you get
ECONNREFUSED error. If the number of connections in netstat is
equal (or at least very close to) the backlog parameter then it's
the backlog parameter, otherwise it's something else.
Gilad
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