• Quacksalber@sh.itjust.works
    link
    fedilink
    arrow-up
    159
    ·
    4 months ago

    Aren’t those almost always race condition bugs? The debugger slows execution, so the bug won’t appear when debugging.

    • BlueKey@fedia.ioOP
      link
      fedilink
      arrow-up
      86
      arrow-down
      2
      ·
      4 months ago

      Turned out that the bug ocurred randomly. The first tries I just had the “luck” that it only happened when the breakpoints were on.
      Fixed it by now btw.

      • Skullgrid@lemmy.world
        link
        fedilink
        arrow-up
        95
        arrow-down
        2
        ·
        4 months ago

        bug ocurred randomly.

        Fixed it by now btw.

        someone’s not sharing the actual root cause.

        • BlueKey@fedia.ioOP
          link
          fedilink
          arrow-up
          60
          ·
          4 months ago

          I’m new to Go and wanted to copy some text-data from a stream into the outputstream of the HTTP response. I was copying the data to and from a []byte with a single Read() and Write() call and expexted everything to be copied as the buffer is always the size of the while data. Turns out Read() sometimes fills the whole buffer and sometimes don’t.
          Now I’m using io.Copy().

          • dfyx@lemmy.helios42.de
            link
            fedilink
            arrow-up
            51
            ·
            4 months ago

            Note that this isn’t specific to Go. Reading from stream-like data, be it TCP connections, files or whatever always comes with the risk that not all data is present in the local buffer yet. The vast majority of read operations returns the number of bytes that could be read and you should call them in a loop. Same of write operations actually, if you’re writing to a stream-like object as the write buffers may be smaller than what you’re trying to write.

            • bl_r@lemmy.dbzer0.com
              link
              fedilink
              arrow-up
              13
              ·
              4 months ago

              I’ve run into the same problem with an API server I wrote in rust. I noticed this bug 5 minutes before a demo and panicked, but fixed it with a 1 second sleep. Eventually, I implemented a more permanent fix by changing the simplistic io calls to ones better designed for streams

            • xthexder@l.sw0.com
              link
              fedilink
              arrow-up
              3
              ·
              4 months ago

              Ah yes… several years ago now I was working on a tool called Toxiproxy that (among other things) could slice up the stream chunks into many random small pieces before forwarding them along. It turned out to be very useful for testing applications for this kind of bug.

      • dunz@feddit.nu
        link
        fedilink
        arrow-up
        17
        ·
        4 months ago

        I had a bug like that today . A system showed 404, but about 50% of the time. Turns out I had two vhosts with the same name, and it hit them roughly evenly 😃

        • vortexsurfer@lemmy.world
          link
          fedilink
          arrow-up
          2
          ·
          4 months ago

          Had a similar thing at work not long ago.

          A newly deployed version of a component in our system was only partially working, and the failures seemed to be random. It’s a distributed system, so the error could be in many places. After reading the logs for a while I realized that only some messages were coming through (via a message queue) to this component, which made no sense. The old version (on a different server) had been stopped, I had verified it myself days earlier.

          Turns out that the server with the old version had been rebooted in the meantime, therefore the old component had started running again, and was listening to the same message queue! So it was fairly random which one actually received each message in the queue 😂

          Problem solved by stopping the old container again and removing it completely so it wouldn’t start again at the next boot.

    • ExtraMedicated@lemmy.world
      link
      fedilink
      English
      arrow-up
      12
      ·
      4 months ago

      I had one years ago with internet explorer that ended up being because “console.log” was not defined in that browser unless you had the console window open. That was fun to troublshoot.

      • xthexder@l.sw0.com
        link
        fedilink
        arrow-up
        2
        ·
        4 months ago

        And that’s where Release with debug symbols comes in. Definitely harder to track down what’s going on when it skips 10 lines of code in one step though. Usually my code ends up the other way though, because debug mode has extra assertions to catch things like uninitialized memory or access-after-free (I think specifically MSVC sets memory to 0xcdcdcdcd on free in debug mode).