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Re: [ftpbench] Client limit in oftpd identified

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  • Dan Kegel
    ... I suppose I could modify dklimits.c to probe to see how many threads can be created. (I wonder if that s dangerous?) ... The 2.4 kernel will raise that
    Message 1 of 1 , Mar 13 11:01 PM
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      shane@... wrote:
      > dkftpbench has helped me isolate a limit in the oftpd server. Right
      > now oftpd creates two threads for each client connection: one to
      > handle the control channel I/O and one to act as a timeout watchdog.
      > Unfortunately, Linux creates a new process for each thread, and
      > limits the user to 256 processes.

      I suppose I could modify dklimits.c to probe to see how many threads
      can be created. (I wonder if that's dangerous?)

      > This limit can be avoided by using the setrlimit() command while
      > oftpd is still running as root. Further, by moving the timeout
      > watchdog to a single thread, the number of threads can be effectively
      > cut in half. There's still a built-in limit to number of processes
      > in Linux - somewhere around 1000 I believe. oftpd will probably
      > never be able to run 5000 clients unless Linux changes its thread
      > model. :(

      The 2.4 kernel will raise that limit significantly, though each thread
      will still take a fair bit of RAM.

      > Any thoughts as to when a bakeoff might be held? If there's a date,
      > I can try to get a new release with the single watchdog thread and
      > a raised RLIMIT_NPROC in place beforehand. This won't let oftpd
      > compete with betaftpd, but it should let it stomp wu-ftpd, proftpd,
      > and ncftpd. :)

      My day job is interfering with my dkftpbench activities these days -
      the bakeoff will probably be delayed for a month or so. But don't
      let that stop you -- I'll happily accept your fixed up version whenever
      you manage to hit a couple hundred users, and measure it here.

      Glad dkftpbench helped you!

      - Dan
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