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Re: [PATCH] SO_REUSEPORT support for listen sockets

Maxim Dounin
July 26, 2013 07:26AM
Hello!

On Fri, Jul 26, 2013 at 03:59:47AM -0700, Piotr Sikora wrote:

> Hey,
>
> > @@ -76,6 +78,13 @@
> > 0,
> > NULL },
> >
> > + { ngx_string("so_reuseport"),
> > + NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
> > + ngx_set_so_reuseport,
> > + 0,
> > + 0,
> > + NULL },
> > +
> > { ngx_string("debug_points"),
> > NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
> > ngx_conf_set_enum_slot,
> > @@ -1361,3 +1370,24 @@
> >
> > return NGX_CONF_OK;
> > }
> > +
> > +
> > +static char *
> > +ngx_set_so_reuseport(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
> > +{
> > + ngx_str_t *value;
> > + ngx_core_conf_t *ccf;
> > +
> > + ccf = (ngx_core_conf_t *) conf;
> > +
> > + value = (ngx_str_t *) cf->args->elts;
> > +
> > + if (ngx_strcmp(value[1].data, "on") == 0) {
> > + ccf->so_reuseport = 1;
> > + } else if (ngx_strcmp(value[1].data, "off") == 0) {
> > + ccf->so_reuseport = 0;
> > + } else {
> > + return "invalid value";
> > + }
> > + return NGX_CONF_OK;
> > +}
>
> This can be replaced with ngx_conf_set_flag_slot(), i.e.:
>
> + { ngx_string("so_reuseport"),
> + NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_FLAG,
> + ngx_conf_set_flag_slot,
> + 0,
> + offsetof(ngx_core_conf_t, so_reuseport),
> + NULL },

If it's kept as a global setting, it would be good idea to move
this into events module if possible.

> Also:
> 1) like Tom said, you definitely need to guard code to make sure
> SO_REUSEPORT is available,
> 2) this feature should be disabled on DragonFly versions prior to the
> 740d1d9 commit, because it clearly wouldn't do any good there,

I believe SO_REUSEPORT doesn't do accept() load balancing on many
OSes right now (e.g. FreeBSD doesn't do that), and it might not be
a good idea to track this in nginx code. It might be better to
just allow users to decide whether to use it or not. Not sure though.

> 3) it might make sense to expose this as an option of "listen"
> directive, instead of a global setting,

Agree.

> 4) how does this (OS-level sharding) play with nginx's upgrade process
> (forking of new binary and passing listening fds)? Are there any
> side-effects of this change that could result in dropped packets /
> requests?

And obvious downside I see is that with the SO_REUSEPORT causes OS
to allow duplicate bindings from different processes, which makes
it possible to unintentionally run 2 copies of nginx. It might be
also possible that configuration test will start to do bad things
as a result.

--
Maxim Dounin
http://nginx.org/en/donation.html

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Subject Author Views Posted

[PATCH] SO_REUSEPORT support for listen sockets

Sepherosa Ziehau 4721 July 26, 2013 04:10AM

Re: [PATCH] SO_REUSEPORT support for listen sockets

Tom van der Woerdt 893 July 26, 2013 04:32AM

Re: [PATCH] SO_REUSEPORT support for listen sockets

Piotr Sikora 717 July 26, 2013 07:02AM

Re: [PATCH] SO_REUSEPORT support for listen sockets

Maxim Dounin 951 July 26, 2013 07:26AM

Re: [PATCH] SO_REUSEPORT support for listen sockets

Sepherosa Ziehau 822 July 28, 2013 09:24AM

Re: [PATCH] SO_REUSEPORT support for listen sockets

Sepherosa Ziehau 811 July 29, 2013 05:54AM

Re: [PATCH] SO_REUSEPORT support for listen sockets

Sepherosa Ziehau 672 July 28, 2013 09:12AM

Re: [PATCH] SO_REUSEPORT support for listen sockets

Maxim Dounin 797 July 29, 2013 10:58AM

Re: [PATCH] SO_REUSEPORT support for listen sockets

Sepherosa Ziehau 1157 July 30, 2013 04:24AM



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