Re: babeltrace 2.1.2: sink.ctf.fs does not deduplicate identical clocks

On Tue, Aug 4, 2026 at 11:28 AM MOESSBAUER, Felix via lttng-dev
<[email protected]> wrote:
>
> Hi,
>
> while porting the bt2-ftrace-to-ctf [1] plugin to babeltrace 2.1, I
> noticed that the sink.ctf.fs creates invalid clock definitions if
> multiple stream-classes share the same clock-class. In this case, the
> clock definition is added multiple times to the CTF 2 metadata,
> resulting in the following assertion on read-back:
>
> ERROR:    [Babeltrace CLI] (babeltrace2.c:2705)
>   Command-line error: retcode=1
> CAUSED BY [Source auto-discovery] (autodisc/autodisc.c:493)
>   babeltrace.support-info query failed.
> CAUSED BY [libbabeltrace2] (lib/graph/query-executor.c:233)
>   Component class's "query" method failed: query-exec-
> addr=0x55cba00c12e0, cc-addr=0x55cba00b4100, cc-type=SOURCE, cc-
> name="fs", cc-partial-descr="Read CTF traces from
>   the file sy", cc-is-frozen=0, cc-so-handle-addr=0x55cba00b1930, cc-
> so-handle-path="<...>/build/babeltrace-plugin-ctf.so",
>   object="babeltrace.support-info", params-addr=0x55cba00cd470, params-
> type=MAP, params-element-count=2, log-level=WARNING
> CAUSED BY ['source.ctf.fs'] (plugins/ctf/common/src/metadata/json/ctf-
> 2-metadata-stream-parser.cpp:130)
>   [1:1 @ 8512 bytes] Invalid fragment #12.
> CAUSED BY ['source.ctf.fs'] (plugins/ctf/common/src/metadata/json/ctf-
> 2-metadata-stream-parser.cpp:367)
>   [1:1 @ 17024 bytes] Duplicate clock class fragment with ID `local`.

See <https://review.lttng.org/c/babeltrace/+/18460>.

Let's continue the discussion on Gerrit if need be.

Thank you for the report and reproducer.

Philippe

>
> When running with MIP=0, the CTF 1.8 data does not have this issue (or
> the reader ignores the duplicated definitions).
>
> [1] https://github.com/siemens/bt2-ftrace-to-ctf
>
> Attached you will find an AI generated reproducer using just the
> babeltrace2 Python bindings.
>
> Best regards,
> Felix Moessbauer
>
> --
> Siemens AG
> Linux Expert Center
> Friedrich-Ludwig-Bauer-Str. 3
> 85748 Garching, Germany
>