babeltrace2-source.ctf.lttng-live(7) — Linux manual page


BABELTRACE2-SOURCE()                                BABELTRACE2-SOURCE()

NAME         top

       babeltrace2-source.ctf.lttng-live - Babeltrace 2's LTTng live
       source component class

DESCRIPTION         top

       A Babeltrace 2 source.ctf.lttng-live message iterator connects to
       a local or remote LTTng (see <>) relay daemon,
       receives the streams of a specific tracing session, and emits
       corresponding messages.

           CTF streams over
           LTTng live (TCP)
             |   +--------------------+
             |   | src.ctf.lttng-live |
             '-->|                    |
                 |                out @--> Sorted messages of one
                 +--------------------+    or more streams

       More information about LTTng live is available in the LTTng
       Documentation (see <>).

       See babeltrace2-intro(7) to learn more about the Babeltrace 2
       project and its core concepts.

       A source.ctf.lttng-live component has a single output port: its
       message iterator muxes (sorts) the messages from the various CTF
       data streams internally.

       A source.ctf.lttng-live message iterator handles the messages of
       one, and only one LTTng tracing session. A single LTTng tracing
       session can contain one or more traces, depending on the active
       tracing domains and the configured user space buffering scheme.

       The component connects to an LTTng relay daemon using the inputs
       parameter. This is an array of exactly one string which is the
       URL of the LTTng relay daemon to connect to.

       By default, if the remote tracing session name does not exist,
       the message iterator returns "try again later". This default mode
       makes the message iterator never end: even if the remote tracing
       session is destroyed, the message iterator keeps on waiting for a
       tracing session with the same name to exist. You can change this
       behaviour with the session-not-found-action initialization


           As of this version, you can only create one message iterator
           per source.ctf.lttng-live component. This is because the
           LTTng live protocol accepts at most one client per tracing
           session per LTTng relay daemon.


       inputs=URL [array of one string]
           Use URL to connect to the LTTng relay daemon.

           URL is an array of exactly one string of which the format is:


               LTTng relay daemon’s host name or IP address.

               LTTng relay daemon’s listening port.

               If not specified, the component uses the default port

               Target’s host name or IP address.

               Name of the LTTng tracing session from which to receive

       session-not-found-action=(continue | fail | end) [optional
           When the message iterator does not find the specified remote
           tracing session (SESSION part of the inputs parameter), do
           one of:

           continue (default)
               Keep on trying, returning "try again later" to the
               downstream user until the tracing session exists.

               With this action, the message iterator never ends, as the
               LTTng live protocol cannot currently indicate that a
               tracing session will never exist.



PORTS         top

           | src.ctf.lttng-live |
           |                    |
           |                out @

           Single output port.

QUERY OBJECTS         top
       See to learn more
       about this query object.

       For a string input which honors the LTTng live URL format (see
       the inputs parameter), the result object is 0.75.

       You can query the sessions object to get a list of available
       LTTng tracing sessions for a given LTTng relay daemon URL.


       url=URL [string]
           Use URL to connect to the LTTng relay daemon.

           The format of URL is:


               LTTng relay daemon’s host name or IP address.

               LTTng relay daemon’s listening port.

               If not specified, the query operation uses the default
               port (5344).

       Result object (array of maps, one element for each available
       tracing session):

       client-count [unsigned integer]
           Current number of LTTng live clients connected to the relay
           daemon to receive data from this tracing session.

       session-name [string]
           Tracing session’s name.

       stream-count [unsigned integer]
           Current number of CTF streams in this tracing sessions,
           including the metadata streams.

       target-hostname [string]
           Hostname of the tracing session.

           This is not necessarily the relay daemon’s hostname.

       timer-us [unsigned integer]
           Tracing session’s configured live timer’s period (µs) (see

       url [string]
           URL to use as the first element of the inputs parameter to
           connect to the same LTTng relay daemon and receive data from
           this tracing session.

BUGS         top

       If you encounter any issue or usability problem, please report it
       on the Babeltrace bug tracker (see

RESOURCES         top

       The Babeltrace project shares some communication channels with
       the LTTng project (see <>).

       •   Babeltrace website (see <>)

       •   Mailing list (see <>) for support and

       •   IRC channel (see <irc://>): #lttng on

       •   Bug tracker (see

       •   Git repository (see

       •   GitHub project (see <>)

       •   Continuous integration (see

       •   Code review (see

AUTHORS         top

       The Babeltrace 2 project is the result of hard work by many
       regular developers and occasional contributors.

       The current project maintainer is Jérémie Galarneau

COPYRIGHT         top

       This component class is part of the Babeltrace 2 project.

       Babeltrace is distributed under the MIT license (see

SEE ALSO         top

       babeltrace2-intro(7), babeltrace2-plugin-ctf(7), lttng-relayd(8),

COLOPHON         top

       This page is part of the babeltrace (trace read and write
       libraries and a trace converter) project.  Information about the
       project can be found at ⟨⟩.  If
       you have a bug report for this manual page, send it to  This page was obtained from the
       project's upstream Git repository
       ⟨git://⟩ on 2024-06-14.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-05-31.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to


Pages that refer to this page: babeltrace2(1)babeltrace2-convert(1)babeltrace2-plugin-ctf(7)