[FASTCGI] Socket error (EAGAIN) at high load

Jay Sprenkle jsprenkle at gmail.com
Mon Jul 23 17:24:33 EDT 2012


The comment I found talks about Linux 2.0  ( "This works around a problem
on Linux 2.0.x" http://www.fastcgi.com/devkit/libfcgi/os_unix.c  )
Have you asked about it on the linux dev mailing lists?
Since we're at 3.5 now you might think it had been looked at by now.


On Mon, Jul 23, 2012 at 3:55 PM, Dean Banks <connexity2 at gmail.com> wrote:

> Hi all,
>
> I'm running an FCGI 2.4.1-based  C application over a Unix domain socket
> behind nginx on Linux 2.6.32.  At periods of high load, I get a lot of
> EAGAIN errors from nginx, implying that my app is not draining the receive
> buffer fast enough.
>
> I have a high number of FDs configured and socket buffers are
>
> SO_RCVBUF = 256960
> SO_SNDBUF = 256960
>
> It appears that reducing READABLE_UNIX_FD_DROP_DEAD_**TIMEVAL from the
> default of 2.0 seconds may be a reasonable next step to reduce the volume
> of EAGAIN errors under load, but other than a "conservative" value of 2.0
> and a "doesn't work" value of 0.0, I'm having a hard time picking a
> starting point to iterate around.
>
> As an aside, the source mentions that the timeout is required to work
> around a kernel bug,  though without additional information it's not clear
> if the bug has been addressed.  Is the timeout still required?
> ---

*"Why do you have that banana in your ear?"
"To keep away the alligators."
"But there are no alligators here."
"See! It's working!"*
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