[PATCH] SO_REUSEPORT support for listen sockets (round 3)

Sepherosa Ziehau sepherosa at gmail.com
Thu Aug 29 13:24:00 UTC 2013

Hi all,

Sorry for the top post.  Any follow-up on this?  Or I should just keep it
as a local patch?

Best Regards,

On Fri, Aug 2, 2013 at 1:16 PM, Sepherosa Ziehau <sepherosa at gmail.com>wrote:

> Hi all,
> Here is another round of SO_REUSEPORT support.  The plot is changed a
> little bit to allow smooth configure reloading and binary upgrading.
> Here is what happens when so_reuseport is enable (this does not affect
> single process model):
> - Master creates the listen sockets w/ SO_REUSEPORT, but does not
> configure them
> - The first worker process will inherit the listen sockets created by
> master and configure them
> - After master forked the first worker process all listen sockets are
> closed
> - The rest of the workers will create their own listen sockets w/
> - During binary upgrade, listen sockets are no longer passed through
> environment variables, since new master will create its own listen
> sockets.  Well, the old master actually does not have any listen
> sockets opened :).
> The idea behind this plot is that at any given time, there is always
> one listen socket left, which could inherit the syncaches and pending
> sockets on the to-be-closed listen sockets.  The inheritance itself is
> handled by the kernel; I implemented this inheritance for DragonFlyBSD
> recently (
> http://gitweb.dragonflybsd.org/dragonfly.git/commit/02ad2f0b874fb0a45eb69750219f79f5e8982272
> ).
>  I am not tracking Linux's code, but I think Linux side will
> eventually get (or already got) the proper fix.
> The patch itself:
> http://leaf.dragonflybsd.org/~sephe/ngx_soreuseport3.diff
> Configuration reloading and binary upgrading will not be interfered as
> w/ the first 2 patches.
> Binary upgrading reverting method 1 ("Send the HUP signal to the old
> master process. ...") will not be interfered as w/ the first 2
> patches.  There still could be some glitch (but not that worse as w/
> the first 2 patches) if binary upgrading reverting method 2 ("Send the
> TERM signal to the new master process. ...") is used.  I think we
> probably just need to mention that in the document.
> Best Regards,
> sephe
> --
> Tomorrow Will Never Die

Tomorrow Will Never Die
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