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  1. Erlang/OTP
  2. ERL-959

Distribution inet send_cnt & recv_cnt reports incorrect values


    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Not a Bug
    • Affects Version/s: 22.0.1
    • Fix Version/s: None
    • Component/s: inets
    • Labels:


      Packet counts reported by distribution link are either too low or too high.

      For example, the network interface reports ~3kpps TX in total, but send_cnt via erlang:port_info/2 reports 0.4pps (7500x fewer pps).

      On the same host, the network interface reports ~3kpps RX, but recv_cnt reports 16kpps (5x more).

      Furthermore, if send_cnt is 0.4pps how can send_bytes be 100MB/s ? A TCP packet cannot exceed 64K in Linux, and according to recv_cnt / recv_bytes received packets do not exceed 1.5KB (the Ethernet MTU site), but sent packets exceed 150MB...

      I've attached the relevant metrics screenshots. Will package the entire setup in Docker Compose and share so that you can reproduce locally.

      1. erl-959.tar
        107 kB
        Gerhard Lazu
      2. erl-959.tar.sha256
        0.1 kB
        Gerhard Lazu
      1. avg-inet-packet-size-explain.png
        480 kB
      2. no-tls-dist-inet-avg-packet-size-received.png
        1.46 MB
      3. no-tls-dist-inet-avg-packet-size-sent.png
        1.48 MB
      4. no-tls-dist-inet-overview.png
        1.63 MB
      5. rabbitmq-overview-tls-dist-1mb-inet-buffer.png
        1009 kB
      6. rabbitmq-overview-tls-dist-default-inet-buffer.png
        958 kB
      7. tls-dist-1mb-inet-buffer.png
        1.48 MB
      8. tls-dist-default-inet-buffer.png
        1.44 MB
      9. tls-dist-inet-avg-packet-size-vs-avg-tcp-packet-values.png
        2.16 MB
      10. tls-dist-processes-1mb-inet-buffer.png
        1.56 MB
      11. tls-dist-processes-default-inet-buffer.png
        1.70 MB



          • Assignee:
            lukas Lukas Larsson
            gerhard Gerhard Lazu
          • Votes:
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            • Created: