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posted by janrinok on Sunday December 21 2014, @04:54PM   Printer-friendly
from the show-stopper-or-rare-event? dept.

Noted Linux expert Chris Siebenmann has described two catastrophic failures involving systemd.

One of the problems he encountered with systemd became apparent during a disastrous upgrade of a system from Fedora 20 to Fedora 21. It involved PID 1 segfaulting during the upgrade process. He isn't the only victim to suffer from this type of bad experience, either. The bug report for this problem is still showing a status of NEW, nearly a month after it was opened.

The second problem with systemd that he describes involves the journalctl utility. It displays log messages with long lines in a way that requires sideways scrolling, as well as displaying all messages since the beginning of time, in forward chronological order. Both of these behaviors contribute to making the tool much less usable, especially in critical situations where time and efficiency are of the essence.

Problems like these raise some serious questions about systemd, and its suitability for use by major Linux distros like Fedora and Debian. How can systemd be used if it can segfault in such a way, or if the tools that are provided to assist with the recovery exhibit such counter-intuitive, if not outright useless, behavior?

Editor's Comment: I am not a supporter of systemd, but if there are only 2 such reported occurrences of this fault, as noted in one of the links, then perhaps it is not a widespread fault but actually a very rare one. This would certainly explain - although not justify - why there has been so little apparent interest being shown by the maintainers. Nevertheless, the fault should still be fixed.

 
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  • (Score: 4, Interesting) by fnj on Sunday December 21 2014, @08:08PM

    by fnj (1654) on Sunday December 21 2014, @08:08PM (#128107)

    FTFS:

    The second problem with systemd that he describes involves the journalctl utility. It displays log messages with long lines in a way that requires sideways scrolling, as well as displaying all messages since the beginning of time, in forward chronological order. Both of these behaviors contribute to making the tool much less usable, especially in critical situations where time and efficiency are of the essence.

    Not a systemd advocate here, but that is a question of familiarity with the tools, which is to say willingness to learn. The author whose article is being summarized, did not try very hard. In fact, I would say he is not much of a Unix user in spirit. Try "man journalctl" sometime. You will see stuff like:

    "-b [ID][┬▒offset], --boot=[ID][┬▒offset] Show messages from a specific boot. This will add a match for "_BOOT_ID="."

    How do you do that when not using systemd? Hmmm?

    "-- no-full The second problem with systemd that he describes involves the journalctl utility. It displays log messages with long lines in a way that requires sideways scrolling, as well as displaying all messages since the beginning of time, in forward chronological order. Both of these behaviors contribute to making the tool much less usable, especially in critical situations where time and efficiency are of the essence."

    That is more control than you get with "less /var/log/messages".

    "-n, --lines Show the most recent journal events and limit the number of events shown. If --follow is used, this option is implied. The argument is a positive integer or "all" to disable line limiting. The default value is 10 if no argument is given."

    That gives you recent lines at least as easily as using tail, or feeding options to less, does.

    "-r, --reverse Reverse output so that the newest entries are displayed first."

    I'll leave that as an exercise for you to figure out when not using journalctl - have a ball.

    "--since=, --until= Start showing entries on or newer than the specified date[/time], or on or older than the specified date[/time], respectively."

    I'd say that is a lot more straightforward than doing similar selections without using journalctl.

    There is a lot more; journalctl has an incredibly rich set of options, and you can pipe it to use your favorite traditional tools too. The claim that journalctl "displays all messages since the beginning of time" is just ignorant.

    So in summary, out of fairness, I am calling utter bullshit.

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  • (Score: 0) by Anonymous Coward on Sunday December 21 2014, @08:38PM

    by Anonymous Coward on Sunday December 21 2014, @08:38PM (#128114)

    > So in summary, out of fairness, I am calling utter bullshit.

    It really doesn't help the anti-systemd people to be spewing their low-information complaints. I'm sure there are significant problems with systemd, but every PEBKAC and ultra-low impact bug that gets its own damn story here ends up making me doubt the competence of the complainers Crying wolf ain't helping their cause.

    • (Score: 2) by fnj on Sunday December 21 2014, @08:43PM

      by fnj (1654) on Sunday December 21 2014, @08:43PM (#128116)

      Couldn't agree more. I'll just point out, it is only the less important part of the article which I was focusing on. The most important point is highly valid.

    • (Score: 0) by Anonymous Coward on Sunday December 21 2014, @09:17PM

      by Anonymous Coward on Sunday December 21 2014, @09:17PM (#128125)

      I agree, and at this point I'm not taking anything said pro- or anti-systemd seriously. This long ago passed through its brief phase as a discussion on technological merit to some sort of socio-political inter-faction conflict. In that kind of environment, any figure or argument may very well be a sort of strawman, or a fake strawman set up to expose strawmanning by the other side, etc. etc.

      The anti-systemd spamming AC who is over-fond of the carriage return, for example, doesn't make any sense. Those comments ask me to believe that there exists a person who is so terrified of his own system that he reads SN specifically to hear about problems with systemd, yet that this person is unwilling or unable to 1) switch distros or 2) read through the systemd bug report list directly, where each of these stories ends up linking, since none of these are new bugs! That is completely irrational. However, it provides a nice way to build up examples of those who are against systemd as deranged. It would be quite effective for systemd proponents to simply link to each of these comments in order to show their own comparative rationality. ...unless, of course, certain evidence will at some point appear indicating that these comments are actually made by someone who has some vested interest in the success of systemd, which would be conveniently effective as for the anti- folks.

      In short: none of this makes sense on the surface, and to attempt to look beneath the surface is a Sisyphean effort.

      • (Score: 0) by Anonymous Coward on Monday December 22 2014, @12:24AM

        by Anonymous Coward on Monday December 22 2014, @12:24AM (#128170)

        I don't think that that AC is lying.

        I, too, do find that I'm constantly surprised by the bugs in systemd. Not being able to cancel a boot-time fsck run? I never would have expected that to be broken under systemd. Pid 1 crashing? I could see it happening, but I would have thought that systemd would be much more reliable than that. Binary log files? I thought everybody with a brain figured out that was a bad idea just by thinking about it for a few seconds. Poor formatting of the text version of the binary log files? This is something that even an amateur programmer can do properly.

        I'm also surprised that these bugs haven't been fixed, even after years in some cases. These are major bugs. They're not tolerable at all. The mere fact that they exist means that something is very wrong with systemd's architecture and development practices.

        I don't really have to worry about all of this, though, having moved to FreeBSD some time ago. But not everyone has that luxury, so I can see why they need this site to keep them updated with the latest dumbness that has been discovered with systemd.

    • (Score: 3, Interesting) by novak on Sunday December 21 2014, @09:25PM

      by novak (4683) on Sunday December 21 2014, @09:25PM (#128128) Homepage

      Hm, yeah, that's because there's (in my mind, anyhow) two categories of systemd opposers.
      First, you've got the people actually interested in minimalism. They have, over time, probably been moving to more minimal systems, been building or testing software which replaces bloated parts of userspace, and generally simplifying their computing. They do not plan to use systemd, because it's the opposite of what they have been working towards. So they don't. They either use another distro or remove systemd from their favorite, because it comes with the territory of minimalism that you have to know some system internals. Or they jump to BSD because they realize that a lot of BSD code is cleaner and more minimal anyways.

      Then, you've got complainers. People that can barely pipe two commands together but that worship the mythical "unix philosophy," which, to be fair, linux does not adhere to particularly well anywhere. They have no particular allegiance to any software, and no particular goals for their software either, but because someone told them it was bad, they start screaming bloody murder. So they want their ubuntu or fedora, just without systemd, like that was the only problem with modern linuxes. They think that systemd is going to crash all their computer multiple times daily and delete the logs. (to be fair, it probably will tank reliability... But there's too much momentum behind it to leave it that badly off)

      These complainers drown out all the serious commenters with knowledge of actual problems of systemd, who are just sort of sitting back chuckling that anyone would even consider using systemd at all. I... don't really care about this bug, honestly. I'll never use systemd, but I know there are going to be a ton of bugs, as systemd is all about feature creep. But instead, most of what you hear are wild rants from the uninformed. "A bug! A bug! I told you it was broken!"
      This bug doesn't "prove" that systemd is broken/unreliable. Basic knowledge about its design proves that. This bug is just a bug, which happens to all software, and especially badly-designed bloatware like systemd.

      --
      novak
      • (Score: 2, Insightful) by Nuke on Monday December 22 2014, @12:25AM

        by Nuke (3162) on Monday December 22 2014, @12:25AM (#128171)
        "there's (in my mind, anyhow) two categories of systemd opposers. ....First, you've got the people actually interested in minimalism. .... Then, you've got complainers.......[and also] the serious commenters with knowledge of actual problems of systemd"

        You have given me a flashback to the Monty Python Spanish Inquisition sketch. That's three categories.

        How about a fourth category - those worried abot the unwillingness of the sytsemd team even to acknowledge bugs, like here [linuxveda.com] and here [soylentnews.org].
        • (Score: 2) by novak on Monday December 22 2014, @12:39AM

          by novak (4683) on Monday December 22 2014, @12:39AM (#128177) Homepage

          Bet you didn't expect the Spanish inquisition!

          More seriously, the people interested in minimalism could understand how systemd works and dismiss it due to design. Still just two categories.

          --
          novak
    • (Score: 0) by Anonymous Coward on Monday December 22 2014, @12:14AM

      by Anonymous Coward on Monday December 22 2014, @12:14AM (#128165)

      I can't wait until systemd shits out on you, and you find yourself dealing with several of these alleged "low-information complaints" at the same time, and unable to do a damn thing to fix them.

      I hope it costs you a lot of money, or maybe even your reputation.

      • (Score: 0) by Anonymous Coward on Monday December 22 2014, @01:59AM

        by Anonymous Coward on Monday December 22 2014, @01:59AM (#128194)

        Wishing ill upon somebody just because they don't disagree with your viewpoint is spiteful and narrow-minded. Regardless of how you feel on the subject, you are way out of line here.

        I hope you are just trolling, but if you really are that emotionally invested in a debate over a peace of software, then you need some help, because this is not a healthy mindset to have.

  • (Score: 3, Insightful) by Foobar Bazbot on Monday December 22 2014, @06:52AM

    by Foobar Bazbot (37) on Monday December 22 2014, @06:52AM (#128241) Journal

    Y'know, there's actually a pretty serious problem here, but I completely agree that it's not the problem the complainer thinks it is. Even if you can't be bothered to RTFM, when confronted with a utility outputting to a tty through a weirdly-behaving pager, the most obvious thing to try is not giving it a tty, e.g. journalctl | less, because any sane program checks if it's connected to a tty before doing weird tty stuff. Sure enough, that works -- journalctl dumps plain text to stdout, and less folds or chops long lines exactly as you told it to in your LESS environment variable.

    No, the real problem is that journalctl (and other parts of the systemd ecosystem) takes it upon itself to provide "sane" defaults, and to provide a way to override those defaults -- all completely ignoring and overriding the existing configuration mechanism. In this case, it's journalctl feeding less a fistful of options to override the settings in your LESS environment variable (but you can override the override by setting SYSTEMD_LESS), but much the same thing is the cause of the Magic SysRq story.

    And every time this happens, and someone complains, the systemd developers/enablers just can't see what their problem is -- after all, you can configure what setting systemd overrides the existing configuration with, and that should be enough for anyone!

  • (Score: 3, Informative) by hemocyanin on Monday December 22 2014, @08:37PM

    by hemocyanin (186) on Monday December 22 2014, @08:37PM (#128465) Journal

    "-r, --reverse Reverse output so that the newest entries are displayed first."
    I'll leave that as an exercise for you to figure out when not using journalctl - have a ball.

    Are you saying that showing a text file with line order reversed is hard?

    A handy reference is the sed one liners document. Note, it's ancient, probably first reproduced in cuneiform on clay tablets, but even with sed, some of the regular expression examples are useful:
    http://sed.sourceforge.net/sed1line.txt [sourceforge.net]

    # reverse order of lines (emulates "tac")
      # bug/feature in HHsed v1.5 causes blank lines to be deleted
      sed '1!G;h;$!d'               # method 1
      sed -n '1!G;h;$p'             # method 2

    Or there's "tac" as referenced in the example: http://linux.die.net/man/1/tac [die.net]

    ~$ cat junk.txt
    1
    2
    3
    a
    b
    c
     
    ~$ tac junk.txt
     
    c
    b
    a
    3
    2
    1