[systemd-devel] [PATCH 4/4] core: lazy distribute for Distribute pools

[Shawn Landden]

On Sun, Nov 17, 2013 at 2:28 PM, Zbigniew Jędrzejewski-Szmek
<zbyszek at in.waw.pl> wrote:
> On Sun, Nov 17, 2013 at 08:46:46PM +0100, Lennart Poettering wrote:
>> On Sat, 16.11.13 13:18, Shawn Landden (shawn at churchofgit.com) wrote:
>> >                          <varlistentry>
>> > +                                <term><varname>LazyDistribute=</varname></term>
>> > +                                <listitem><para>Takes an boolean
>> > +                                value. If true, Distribute=n workers will not be spawned
>> > +                                simultameously, but one at a time while connections come it
>> > +                                until n are running. Because of the nature of SO_REUSEPORT workers are
>> > +                                spawned at an exponentially decreasing rate to the number of incoming connections.</para></listitem>
>> > +                        </varlistentry>
>> > +
>> > +                        <varlistentry>
>>
>> Hmm, so I think support for SO_REUSEPORT should just be a special case
>> of the Distribute= logic. i.e. When Distribute= is set but ReusePort is
>> off, then we'd pass the same original listening socket to all services
>> we spawn. If Distribute is set but ReusePort is on then we'd create a
>> new socket when we want to spawn a new instance, and simply bind it to
>> the same sockaddr as the original one.
What types of sockets allow multiple bind()s/accept()s without SO_REUSEPORT?
I don't see what the use is having a socket passed to children that
can't be used.
>>
>> Thinking about this: I have the suspicion that LazyDistribute shouldn't
>> be an option but the normal and only behaviour...
> Agreed.
OK
>
> Also, I think ReusePort=1 should be the default if Distribute is used,
> and the kernel supports it. I don't think there are any downsides.
ReusePort=1 makes it where systemd no longer "sits" on the port which
prevents rogue applications
(root for <1024) from stealing the port.
>
> Zbyszek
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Shawn Landden
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