[lttng-dev] [RELEASE] LTTng-UST 2.12.9 and 2.13.7 (Linux user-space tracer)

[Mathieu Desnoyers]

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.

* New and noteworthy in these releases:

Specific to 2.13.7, a fix for misaligned urcu reader accesses was
introduced. It only applies to the lttng-ust 2.13 branch because
it implements its own "lttng-ust-urcu" flavor.

Also specific to 2.13.7, "sync" vs "unsync" enablers are introduced
to eliminate an O(n*m) algorithm:

     Eliminate iteration over unmodified enablers when synchronizing the
     enablers vs event state.

     The intent is to turn a O(m*n) algorithm (m = number of enablers, n =
     number of event probes) into a O(n) when enabling many additional events
     when tracing is active.

Specifically in 2.12.9, the rfork() wrapper is fixed: it was not
passing the flags arguments. This was fixed in a larger commit
in the master and stable-2.13 branches.

Both stable branches include:

- a build system fix for documentation examples with old autoconf when
   used with a relative path.

- a clang warning fix around volatile qualifier on function pointers.

- Python agent uplift to adapt to modern python (>= 3.10),

- a possible race condition in the ustfork helper.

Enjoy!

Mathieu

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

Detailed change logs:

2024-01-10 (National Houseplant Appreciation Day) lttng-ust 2.13.7
         * fix: invoke MKDIR_P before changing directories
         * fix: -Wsingle-bit-bitfield-constant-conversion with clang16
         * fix: clean java inner class files in examples
         * Introduce sync vs unsync enablers
         * Fix: misaligned urcu reader accesses
         * ustfork: Fix warning about volatile qualifier
         * ustfork: Fix possible race conditions
         * Fix: tracepoint: Remove trailing \ at the end of macro
         * fix: python agent: use stdlib distutils when setuptools is installed
         * fix: python agent: install on Debian python >= 3.10
         * fix: python agent: Add a dependency on generated files
         * python: use setuptools with python >= 3.12

2024-01-10 (National Houseplant Appreciation Day) lttng-ust 2.12.9
         * fix: invoke MKDIR_P before changing directories
         * fix: clean java inner class files in examples
         * ustfork: Fix warning about volatile qualifier
         * ustfork: Fix possible race conditions
         * Fix: FreeBSD: Pass flags arguments to rfork wrapper
         * fix: python agent: use stdlib distutils when setuptools is installed
         * fix: python agent: install on Debian python >= 3.10
         * fix: python agent: Add a dependency on generated files
         * python: use setuptools with python >= 3.12


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