[systemd-devel] Question about service dependency handling in systemd-228

[Bao Nguyen]

Hello everyone,

I would like to have a question regarding to the building dependency and
cycle dependency handling on systemd-228. In my system, I have some socket
and service files, it has a cycle on socket target, when I run on
system-228, systemd-228 throws

[   40.358582] systemd[1]: Set hostname to <MY-2>.
[   41.154231] systemd[1]: nss-lookup.target: Dependency
Before=nss-lookup.target dropped
[   41.297229] systemd[1]: sockets.target: Found ordering cycle on
sockets.target/start
[   41.297236] systemd[1]: sockets.target: Found dependency on
asi-My-5101.socket/start
[   41.297239] systemd[1]: sockets.target: Found dependency on
My-sshd.target/start
[   41.297241] systemd[1]: sockets.target: Found dependency on
My-syncd.service/start
[   41.297244] systemd[1]: sockets.target: Found dependency on
My-nfs-client.service/start
[   41.297246] systemd[1]: sockets.target: Found dependency on
My-handling.service/start
[ SKIP ] Ordering cycle found, skipping My Telnet Server Socket on port 5101
[ SKIP ] Ordering cycle found, skipping My Telnet Server Socket on port 5010
[ SKIP ] Ordering cycle found, skipping My Telnet Server Socket on port 5111
[ SKIP ] Ordering cycle found, skipping asi-vsftpd-MyIO_2.socket
[ SKIP ] Ordering cycle found, skipping My Telnet Server Socket on port 5110
[ SKIP ] Ordering cycle found, skipping My Telnet Server Socket on port 5002
[ SKIP ] Ordering cycle found, skipping My Telnet Server Socket on port 5100
[ SKIP ] Ordering cycle found, skipping Remo...ell Facilities Activation
Socket
[ SKIP ] Ordering cycle found, skipping My Telnet Server Socket on port 5011
[ SKIP ] Ordering cycle found, skipping My sshd target


It said that there is an ordering on the sockets.target, then break the
cycle and SKIP randomly starting other service => the system cannot start.
However I did not meet the same issue on systemd-210 with the same my
services and sockets. Systemd-210 does not break and skip, and my system
can start well.

My question is if there are any significant different about building tree
dependency and handling cycle dependency between systemd-210 and
systemd-228 that can lead to my current situation? I have checked the
change log, source code but not found any useful info

And what does the message "nss-lookup.target: Dependency
Before=nss-lookup.target dropped" mean? I do not see it in systemd-210.

Many thanks for your support,
Best regards,
Naru
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