Parallel Output Wrapping

[crftbt]

Hello, what would cause the output to wrap, instead of having a new line, when Parallel is enabled with OpenRC?

Details from https://gitlab.alpinelinux.org/alpine/aports/-/issues/16226#note_423126

[navi-desu]

hmm, that's odd... output from openrc at boot when rc_parallel is set, should be

<service 1 name> | <service 1 output>                   [ ok ]
<service 3 name> | <service 3 output>                   [ ok ]
<service 2 name> | <service 2 output>                   [ ok ]

sometimes it does print two of those on the same line (a bug, i assume), but on my testing it was rare, so i wonder if there's any kind of specific configuration options to trigger that reported behavior?

note that rc_parallel has some quirks and bugs, which i intend on fixing

[crftbt]

hmm, that's odd... output from openrc at boot when rc_parallel is set, should be

<service 1 name> | <service 1 output>                   [ ok ]
<service 3 name> | <service 3 output>                   [ ok ]
<service 2 name> | <service 2 output>                   [ ok ]

sometimes it does print two of those on the same line (a bug, i assume), but on my testing it was rare, so i wonder if there's any kind of specific configuration options to trigger that reported behavior?

note that rc_parallel has some quirks and bugs, which i intend on fixing

What information in particular would be needed to debug this particular situation?

[navi-desu]

openrc version and a rc.conf which i can reproduce that i think, since in master with just "rc_parallel=Yes" the output is lined up for me

[sertonix]

I think I now know what the problem is. openrc seems to uses different output formats depending on what it is outputting to (I would guess tty or pipe).

In my case the openrc logs are handled by s6-linux-init which writes the logs into multiple locations.

[navi-desu]

just looked at the code, if the output is a color terminal, libeinfo uses a built-in version of tgoto to move back to the same line it originally printed

but if stdout isn't a supported terminal, it simply prints spaces and the [ OK ], leading to piped output being a jumbled mess with rc_parallel on, as we can't jump back

i'm unsure how to proceed with this, some sort of buffering could work, or instead we could simplify the output should rc_parallel be enabled and the tty not a color term? aka print the whole line again, not just the ending

[sertonix]

Maybe print every message with the service line prefixed and always a newline afterwords. Like this:

<service 1 name> | <service 1 output>
<service 3 name> | <service 3 output>
<service 3 name> | [ ok ]
<service 2 name> | <service 2 output>
<service 1 name> | [ ok ]
<service 2 name> | [ ok ]