Memory caps, run time limits, sleep inhibitors, better cron and path units - systemd features that turn out to be handy for running throwaway agent-written code.
  • badmin@lemmy.today
    182·
    13 hours ago

    More obvious, but systemd has a lot of features that a simple cron doesn’t.

    Which cron?

    Oh wait. Why did I assume OP would know there are multiple implementations? 😄

    • 0x0@infosec.pub
      18·
      13 hours ago

      You may have experienced this before. You have an agent write a script, perhaps to do some data analysis. It has a terrible memory leak, and suddenly your machine freezes and (hopefully) the kernel resumes after a bit with an OOM error I’ve had this a few times, and it’s very annoying…

      Holy fuck I can’t stop laughing at their reason for systemd for some reason, probably need an agent summarising their article for me

          • MonkderVierte@lemmy.zip
            11·
            5 hours ago

            I mean, the only thing i needed cgroups for was running rootless containers on Alpine (Openrc). This was something like cgroups = true in their main config. Can it be easier?

            • Magiilaro@feddit.org
              1·
              4 hours ago

              Ok and now tell me how to use cgroups for a random binary, anything that has not buildin cgroups support. That’s were it gets complicated and where systemd can help a lot

              You are using a tool where someone else has solved the hard part to show that no hard part exists in the first place.

              • MonkderVierte@lemmy.zip
                1·
                2 hours ago

                I mean, what use is cgroups if you don’t need it? And what needs it is usually a tool. Tool has it preconfigured for it’s needs, so, easy.

                • Magiilaro@feddit.org
                  1·
                  4 hours ago

                  Yes, that is one of the tools needed. But it is not helping with doing anything meaningful with cgroups. A cgroup without any kind of specific configuration is almost as good as no cgroup at all. That’s what I meant with the hard part.

                  And I did say that systemd makes it stupidly easy, in contrast to the normal easy that cgroups often are.

      • kibiz0r@midwest.socialEnglish
        5·
        10 hours ago

        I remember way back when I was doing Ruby on Rails, we would always wrap the server processes in a manager (I forgot what it’s called) that watches the memory and restarts them when the leaks get too bad. What a ridiculous solution that was.

      • badmin@lemmy.today
        7·
        12 hours ago

        This has been happening forever. This old post always pops up in my mind for some reason as a historic example from an earlier linux boom.

        Unfortunately, people have been pushed to not call out such things, because it’s “not nice”, when as the blog above shows, not calling it out is what’s not nice, and potentially dangerous.

        • frongt@lemmy.zip
          1·
          8 hours ago

          Yeah. I called out someone here on Lemmy for just completely making shit up about some kernel feature, linked the documentation showing the actual meaning, and got downvoted for it.

  • thingsiplay@lemmy.ml
    1·
    8 hours ago

    Is there a way to limit download bandwidth of programs started with this systemd-run command? Without changing some network settings, I just want to do it temporarily on the fly with commandline options.

      • thingsiplay@lemmy.ml
        1·
        5 hours ago

        That’s not the same as network bandwidth. Maybe I used the wrong terminology, I meant download speed, not max downloaded size of data contingent.

        • Magiilaro@feddit.org
          2·
          4 hours ago

          Yes and as I said there is no way to limit the network bandwidth, as far as I know, but limiting the speed that the tool can write to the storage device oftentimes limits the speed of retrieval also.

          Kind of a indirect speed limit for the download, as a workaround.

          • thingsiplay@lemmy.ml
            2·
            4 hours ago

            Ah, I didn’t pick up on that. Well, need to test this out. As a workaround it could work. I don’t have any other special requirements for this, its really a workaround in itself for tools that don’t have this setting. (which annoys me alot) Nice idea btw.

        • badmin@lemmy.today
          2·
          5 hours ago

          There is an ancient fully user-space simple tool called netbrake that works by LD_PRELOADING a library that overrides some functions like recv/sendto (similar to eatmydata’s approach*). It may just work if you don’t have special requirements. If you’re curious, you can see the full list of overridden symbols with:

          readelf -s /path/to/libnetbrake.so | grep -v UND

          If you want a possibly fail-safe (kernel level) solution, you may find with a web search a helpful approach combining tc with cgroups.

          Neither solutions need systemd.

          * The realization that people growing up with SSD’s probably never heard of eatmydata just sunk in.

          • thingsiplay@lemmy.ml
            1·
            5 hours ago

            Thanks for the tip. I will look into it. My use case would be to limit download speed for applications that do not have such a setting (such as Firefox, just an example).

            • badmin@lemmy.today
              1·
              4 hours ago

              such as Firefox

              You can use the cliget extension which generates full CLI commands for major CLI tools. Such tools have many options (e.g. curl’s --rate-limit).

              • thingsiplay@lemmy.ml
                1·
                4 hours ago

                Firefox was just one example of tool that doesn’t provide a limit by itself. I’m looking for a solution that could be applied to any program.