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LTTng Toolchain 2.4.0 is out!


Hi all!

After five release candidates, the LTTng 2.4 stable release, codenamed Époque Opaque, is finally ready!

LTTng Tools 2.4.0

The most important feature of this 2.4 release is the addition of live tracing support. A trace reading client may now connect to the relay daemon to read a trace as it is produced by both kernel and user space tracers.

Here is a short guide demonstrating this feature using Babeltrace v1.2.0:

lttng create my_session --live
lttng enable-event --kernel --all
lttng start

Active sessions can then be listed using Babeltrace:

babeltrace -i lttng-live net://localhost

which will output something like:

net://localhost/host/Hostname/my_session (timer = 1000000, 5 stream(s), 0 client(s) connected)

Then, a connection can be established:

babeltrace -i lttng-live net://localhost/host/Hostname/my_session

See the live reading how-to and the create session section in lttng's man page for more information on this feature.

Another major feature added as part of this release is Java Util Logging (JUL) support. It is now possible to enable events in the new JUL domain. These events are produced using LTTng-UST's new JUL backend. More information is available in lttng's manpage.

Finally, user space event exclusion has been added to lttng's enable-event command which allows users to exclude events even if wildcards are used. This feature is also usable with the --all option.

LTTng-tools changelog

LTTng-UST 2.4.0

This release brings Java Util Logging tracing to LTTng-UST. A new library, liblttng-ust-jul, provides a JUL LogHandler implementation along with the necessary shim to trace events from Java applications. More information is available here, along with an example.

Also of note, shared object base-address tracing has been added as an experimental feature. This feature allows trace readers to perform address to symbol mappings on dynamically loaded libraries by generating the ust_baddr:push and ust_baddr:pop events on calls to dlopen() and dlclose(). See the lttng-ust-dl manpage for more details.

Noteworthy changes:

  • Added tracing instrumentation for pthread mutex lock functions
  • Added event exclusion-list support

LTTng-UST changelog

LTTng-Modules 2.4.0

Noteworthy changes:

  • Addition of a new tracepoint in KVM (kvm_write_tsc_offset)
  • Blacklist ARM gcc 4.8.0, 4.8.1, 4.8.2

LTTng-Modules changelog

Please feel free to email the list about any questions/comments concerning this release at lttng-dev@lists.lttng.org. For bugs or missing documentation, use our bug tracker.

As always you can find the different packages in the Download section.