[RELEASE] LTTng-UST 2.8.0-rc1 (Linux user-space tracer)

[Mathieu Desnoyers]

We announce the first LTTng 2.8 - "Isseki Nicho" release candidate.
LTTng-UST, the Linux Trace Toolkit Next Generation Userspace Tracer,
is a low-overhead application tracer. The library "liblttng-ust" enables
tracing of applications and libraries.

The "Isseki Nicho" LTTng release name is a microbrew beer, following
our usual theme.

Its description:

The result of a collaboration between "Dieu du Ciel!" and Nagano-based
"Shiga Kogen", Isseki Nicho is a strong Imperial Dark Saison offering a
rich roasted malt flavor combined with a complex fruity finish typical
of Saison yeasts.

Here are the new major features included in this release:

--- Shared object base address dump for mapping event to source code ---

If a user takes a UST trace and enables the "ip" and "vpid" contexts,
and the binaries with debug information are available, it is now
possible to infer the location in the source code (dubbed "source
callsite") for UST trace events.

Those contexts can be enabled by lttng using the following command:

$ lttng add-context -u -t ip -t vpid

In order to capture the load addresses of shared objects loaded
with dlopen(), the application should be launched with:

$ LD_PRELOAD="liblttng-ust-dl.so" <path/to/executable>

There is currently a pull request open against Babeltrace
(http://diamon.org/babeltrace) to add the mapping event to
source code feature needed with this LTTng-UST feature:

https://github.com/efficios/babeltrace/pull/30

Here is the produced Babeltrace output with this feature:
    [...]
    [19:53:41.648394410] (+0.000022616) colossus my_provider:my_first_tracepoint: { cpu_id = 2 }, { ip = 0x7F75AEDFB4D4, debug_info = { func = "foo", source_loc = "/home/efficios/example/libhello.c:7" }, vpid = 25577 }, { my_string_field = "hello, tracer", my_integer_field = 42 }
    [19:53:41.648423786] (+0.000029376) colossus my_provider:my_first_tracepoint: { cpu_id = 2 }, { ip = 0x7F75AEDFB5A6, debug_info = { func = "bar", source_loc = "/home/efficios/example/libhello.c:13" }, vpid = 25577 }, { my_string_field = "recoltes et semailles", my_integer_field = 57 }
    [19:53:41.648435726] (+0.000011940) colossus my_provider:my_other_tracepoint: { cpu_id = 2 }, { ip = 0x7F75AEDFB66B, debug_info = { func = "baz", source_loc = "/home/efficios/example/libhello.c:20" }, vpid = 25577 }, { some_field = 1729 }
    [...]

The Trace Compass project master branch currently supports
this mapping event to source code feature. It even allows
to directly open the associated source files with a "goto
source code" action. For more info, visit http://tracecompass.org .


--- Java Application Contexts ---

This new feature allows dynamic application contexts to be both saved
to a trace and used as an event filtering criterion.

An example showing how to define and populate Application Contexts is
provided as part of LTTng-UST's examples.

https://github.com/lttng/lttng-ust/blob/master/doc/examples/java-jul/ApplicationContextExample.java

Application contexts can be added to a channel by using, for example:
$ lttng add-context --jul -t '$app.retriever_name:context_name'

They can also be used to filter events:
$ lttng enable-event --jul my_application_event --filter
'$app.retriever_name:context_name > 52'

See the lttng-enable-event(1) and lttng-add-context(1) man pages for
more information.


Project website: http://lttng.org
Documentation: http://lttng.org/docs
Download link: http://lttng.org/download

Feedback is welcome!

Thanks,

Mathieu

Detailed changelog:
2016-03-18 (Awkward Moments Day) lttng-ust 2.8.0-rc1
        * Fix: remove assertions in lttng-ust-comm init
        * Add tracepoint_disable_destructors()
        * Documentation: fix manpage typo
        * Fix: move lttng_context_is_app to core file
        * Fix: move dummy functions to common file
        * Fix: handle backward probe compatibility for application contexts
        * Fix: application context header size
        * Fix: event ctx get size should be after chan ctx
        * Clarify and simplify the Java agent "Hello" examples
        * Export the stream instance ID
        * Generate and export the sequence number
        * Add stream instance id to the packet header
        * configure.ac: print empty line after AC_OUTPUT
        * configure.ac: macros with no arguments do not need ()
        * configure.ac: standardize indentation to tabs
        * configure.ac: move AC_PROG_SED() close to other AC_PROG_*()
        * configure.ac: test -a -> shell's && (more portable)
        * configure.ac: use test "x$var" = "xyes"
        * configure.ac: AM_CONDITIONAL() accepts two arguments
        * configure.ac: use dnl at appropriate places
        * configure.ac: if -> AS_IF()
        * configure.ac: case -> AS_CASE()
        * configure.ac: add missing quotes in macro calls
        * configure.ac: use macros for version name and description
        * configure.ac: do not use shell eval for known values
        * Add CONTRIBUTING.md
        * Output "(null)" when ctf_string()'s arg is NULL
        * Fix: disable use of __builtin_return_address(0) on 32-bit PowerPC
        * Fix: java agent 32-bit pointer to jlong warning
        * Fix: Use Java 6 syntax in JUL examples
        * Fix: add missing example file to dist tarball
        * Fix: add missing header to dist tarball
        * Fix: add missing LttngContextApi.java to dist tarball
        * Pass the Java app context information using two separate arrays
        * Fix: Correctly report filter notifications on Java agent teardown
        * Add some logging to the AbstractLttngAgent
        * Fix: Clear tracked application contexts upon closing a Java agent
        * Introduce a verbose mode for the Java agent
        * Implement Java agent application context retrieval
        * Turn ISessiondCommand into an abstract class
        * Split the JNI APIs in separate classes
        * Add app context support to ust-ctl protocol
        * Handle application context cmd
        * Implement dynamic types, and application context provider support
        * Fix: handle negative range for LTTNG_UST_REGISTER_TIMEOUT
        * Fix: Ensure the Java JUL messages are correctly formatted
        * Fix: double-free on error sending fields
        * Add CTF enum type support to tracepoint event
        * Fix: missing _GNU_SOURCE define
        * python-lttngust/setup.py.in: update setup() fields
        * Refactor Python agent build and install
        * Fix: remove debugging print() call from Python agent
        * Fix: header size larger than 256 bytes
        * Python agent: Support Agent protocol v2.0
        * Fix: Java agent protocol network endianness consistency
        * Fix: examples jul: add missing files to make dist
        * Fix: Filer -> Filter typo in example
        * Fix: Return the correct list of available Java events
        * Add a toString() to Java agent's EventRule
        * Add API stubs for the Java context info retrievers
        * Receive the event filter string in the Java agent
        * Document the Java filter notification model
        * Add filter change notification mechanism to the Java agent
        * Manage complete "event rules" in the Java agent
        * Introduce a new client listener interface for the Java agent
        * Turn ILttngAgentResponse into an abstract class
        * Remove stale tests/java-jul test
        * Fix: live timer calculation error
        * Fix python agent build/install/uninstall with DESTDIR specified
        * Fix: Don't (re)define STAP_PROBEV
        * Fix: don't dereference NULL pointers
        * Cleanup: Remove unused values
        * Fix: Value stored to 'has_waited' is never read
        * Fix: Argument with 'nonnull' attribute passed null
        * Cleanup: Unnecessary bit shift
        * Clean-up: remove extraneous "found" parameters in ust-elf
        * Fix: sysconf() unchecked return value
        * doc: add Python example
        * Fix: Python agent: do not register twice to same port
        * Fix: potential leaks in error paths
        * Fix: double free in liblttng-ust-dl
        * Fix: make check in OOT build with absolute path
        * Fix: elf: leaks on error paths
        * Cleanup: coding style
        * Cleanup: elf: use off_t for offsets, size_t for len
        * Cleanup: eliminate implicit sign-extension
        * Fix: elf: NULL pointer dereference
        * Fix: add missing ust-elf.h header to dist
        * Fix: make check in out of tree build
        * Fix: old gcc warnings
        * Fix: old gcc warning
        * Fix: remove stale lttng-ust-elf.h from makefile
        * Fix: elf: uninitialized ret
        * Fix: test elf: handle NULL debug file
        * test: elf move constants to top of implementation
        * Fix: elf test prog arg checking
        * baddr statedump: remove dependency on file streams
        * baddr statedump: hold ust lock around allocations
        * Add unit tests for lttng_ust_elf
        * Add memory size, build id, and debug link info to statedump and dl
        * Fix: close socket on protocol error, sendmsg MSG_NOSIGNAL
        * Cleanup: more descriptive error message
        * Fix: add missing ust lock around objd_table_destroy()
        * Fix: application exit race with pthread cancel
        * Cleanup: configure layout for python agent detection
        * Build: python agent: use setup.py over autoconf
        * Build: add python interpreter used by python agent if built
        * Doc: basic lttng ust python agent documentation
        * Build: use AM_PATH_PYTHON to resolve python when building agent
        * Build: only check if python exists in path
        * Update version to 2.8.0-pre
        * Fix: Send the correct Java agent return code when disabling events
        * Fix: Correctly handle the command to disable all events
        * Small refactor of the Java agent's TCP client
        * Rename Java Agent event names to "event"
        * Rename Python agent tracepoint to "event"
        * Allow compiling the Java agent with Java 1.6
        * Restore concurrent build when Java agent is enabled
        * Refactor Java agent to let applications manage the log handlers
        * Doc: add LTTNG_UST_CLOCK_PLUGIN to man page
        * Doc: add LTTNG_UST_GETCPU_PLUGIN to man page
        * Cleanup: Add Javadoc to all public methods and members
        * Fix: Small fixes to the Java agent example files
        * Update doc/java-agent.txt to reflect the new packaging
        * Split Java agent library in 3 separate jars
        * Remove deprecated org.lttng.ust.jul.LTTngAgent class
        * Use tar-ustar format for the dist archive
        * Fix: remove generated file from git tree

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com