About this patch release

2026-06-05 lttng-tools 2.15.1 (National Fish and Chip Day)

• Fix: sessiond: abort when loading an agent session configuration
• Fix: sessiond: deadlock when handling notification overflow
• Fix: sessiond: default kernel probe list missing 9p and dma-fence
• Fix: relayd: wrong session id used in trace chunk existence check
• Fix: relayd: live viewer reads wrong chunk after per-PID clear
• Fix: consumerd: segfault when starting metadata switch timer
• Fix: lttng: truncated session name when it contains spaces
• Fix: lttng: client abort when serializing rotate-session action
• Fix: lttng: vague error reporting in reclaim-memory command
• Fix: lttng: reclaim-memory MI emits generic "channels" element
• Fix: lttng: handle popt parsing errors
• Fix: common: stop-session action serialized as start-session in MI
• Fix: common: enable-event MI emits duplicate exclusions element
• Fix: common: MI XSD names snapshot record action "record-output"
• Fix: common: MI XSD rejects add-context per-context success element
• Fix: common: MI XSD names start/stop-session actions without "_session"
• Fix: common: lockfile fd leaks into consumerd via fork+exec
• Fix: common: uri_compare compares uninitialized union tail
• Fix: common: CPU mask parsing and printing
• Fix: common: drop :: qualifier on *_CLOEXEC for musl compatibility
• Fix: handle failures to find pid cmdline
• Fix: doc: lttng-view(1): remove non-existent '--session' option

Full changelog: v2.15.0...v2.15.1

About LTTng-tools 2.15

This release is named after Péché Mortel, the iconic Imperial Stout from Montréal's Dieu du Ciel! and a long-time team favorite.

Deep black and unapologetically intense, Péché Mortel pours with a dense, mocha-tinted head and an aroma that immediately announces freshly roasted coffee. Decadent and dangerously drinkable, it is the ideal companion for long, cold winter evenings.

The most notable features of this release are:

• CTF 2 as the default trace format, selectable per recording session with
  the --trace-format option of lttng create.
• A reduced memory footprint for user space tracing, including on-demand
  buffer preallocation (--buffer-preallocation) and channel memory reclaim
  (lttng reclaim-memory and the --auto-reclaim-memory policy).
• Improved resiliency of shared LTTng-UST buffers through a new watchdog timer.
• A redesigned lttng list command with memory usage reporting.
• New trigger conditions for lttng add-trigger: channel buffer usage,
  session consumed size, and session rotation start/finish.
• systemd sd_notify() integration for the session and relay daemons.

For a detailed description of these features, read the full LTTng 2.15
announcement: https://github.com/lttng/lttng-tools/releases/tag/v2.15.0