iperf-3.19 2025-05-16

[bmah888]

iperf-3.19 2025-05-16

• Notable user-visible changes

  • iperf3 now supports the use of Multi-Path TCP (MPTCPv1) on Linux
    with the use of the --mptcp flag. (PR add MPTCPv1 support #1661)

  • iperf3 now supports a --cntl-ka option to enable TCP keepalives
    on the control connection. (Cannot test long UDP sessions #812, intermittent connection #835, PR Add control connection keepalive arguments #1423)

  • iperf3 now supports the MSG_TRUNC receive option, specified by
    the --skip-rx-copy. This theoretically improves the rated
    throughput of tests at high bitrates by not delivering network
    payload data to userspace. (feature request: support for MSG_ZEROCOPY and MSG_TRUNC flags #1678, PR Add SKIP-RX-COPY support - using MSG_TRUNC socket option #1717)

  • A bug that caused the bitrate setting to be ignored when bursts
    are set, has been fixed. (Remove the usage of pacing_timer and simplify iperf_mt_send #1773, Iperf3.18 - packet count for burst mode seems broken when sending UDP traffic (on Windows) #1820, PR Fix issue that bitrate is ignored when burst is set (with Nanosleep) #1821, PR Extending PR #1821 fix to PR #1773 for sending when bitrate is set #1848)

  • The congestion control protocol setting, if used, is now
    properly reset between tests. (PR Reset the congestion protocol on the server between tests #1812)

  • iperf3 now exits with a non-error 0 exit code if exiting via a
    SIGTERM, SIGHUP, or SIGINT. (Better daemon mode #1009, PR# 1829)

  • The current behavior of iperf3 with respect to the -n and -k
    options is now documented as correct. (Lower throughtput numbers reported with v3.16 #1768, End test immediately when all number of blocks/bytes sent/received #1775, bytes/blockcount with reverse mode #596, PR Change help to make current -n/-k behavior a Feature #1800)

• Notable developer-visible changes

  • iperf3 now supports a callback function to get the JSON output
    strings. (How to use the iperf library to obtain bandwidth information in real-time at intervals? #1711, PR Add callback function to get JSON Output strings #1798)

  • iperf3 now builds correctly with gcc-15 (Fails To Build From Source with GCC-15 #1838, PR fix build with gcc-15 #1805)

  • Various memory leaks were fixed (Fix two minor memory / file descriptor leaks in iperf_tcp_connect(). #1881, PR#1823, Remove (by design) memory-leak by from the Intervals Results linked-list #1814, PR#1822)

  • A potential segfault crash was fixed (Fix Segfault in iperf_err(exit) #1807)

  • Improved warning messages when reading malformed JSON messages
    (PR JSON_Read() warning messages enhancements #1817)

  • The Github CI configuration was changed to use a more up-to-date
    set of runners (PR GitHub actions: Remove deprecated CI runner, add more diverse set of … #1864)

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This discussion was created from the release iperf-3.19 2025-05-16.