Re: question about 3sec timeouts with tcp

[Marlon de Boer]

Marlon de Boer wrote:
> Hi list,
>
> I'm trying to solve a problem with 3sec timeouts with tcp connections,we
> are seeing these timeouts in both production and test environments. The
> timeouts mainly occur from our webservers connecting to our mysql
> backend. (about 450 webservers, connecting to somewhat 400 database
> servers, serving 13 million pageviews per hour during busy hours).
>

I've found the cause, it has to do with the tcp backlog. I've raise
the backlog in mysql via back_log = 8192 and in the kernel via echo
8192 > /proc/sys/net/core/somaxconn, and everything worked just fine.

For some really high speed operational I also tuned
net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1

Kind regards

Marlon de Boer
System engineer for www.hyves.nl



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