[systemd-devel] Questions about socket activated services

Andrei Borzenkov arvidjaar at gmail.com
Sat May 30 10:33:22 PDT 2015

В Sat, 30 May 2015 21:36:02 +0800
cee1 <fykcee1 at gmail.com> пишет:

> Hi all,
> Which service type should a socket activated service be?
> 1. For systemd-udevd.service and systemd-journald.service, they are notify type
> 2. For dbus.service, it is simple type

It can be any type. notify is always preferred if started program
supports it.

> Does socket activation handles the timeout case?
> E.g. A.service connects to B.socket, but B.service spends a long time
> to be ready, may cause A.service receives ETIMEDOUT?

I suppose it is possible with Accept=false. With Accept=true connection
is accepted by systemd itself.

> When the service is activated, systemd will still listen to the socket
> but do nothing for incoming data, right?

Yes for Accept=false. For Accept=true it is always systemd which accepts

> BTW, netstat -lp shows only systemd is listening to a socket, but not
> show the one who also is listening to the socket, e.g.
> """
> unix  2      [ ACC ]     SEQPACKET  LISTENING     326      1/systemd
>          /run/udev/control
> """
> Curious why?

I think it is more netstat issue, apparently it shows the first process
it finds.


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