[Unreleased]

Added

• Pf2.profile now accepts the same options as Pf2.start.

• The resulting profile now has collected_sample_count and dropped_sample_count fields.

Fixed

• Samples captured after the collector thread was stopped now get included in the profile.

• This shouldn’t matter in practice (this all happens after Pf2.stop is called).

Changed

• Accepted max stack depth is expanded to 1024 for Ruby (was 200) and 512 for native (was 300).

• This is not configurable, but should be sufficient for most use cases. Please open an issue if you need higher limits.

• Pf2.profile now accepts the same parameters as Pf2.start.

• Internal changes

• Updated libbacktrace to the latest version as of 2026/1/8.

• Tests are now much more stabilized.

[0.11.3] - 2025-12-28

This version is for testing the new release process through Trusted Publishing. All code is identical to 0.11.2.

[0.11.2] - 2025-12-28

0.11.1 was yanked since it was accidentally published without libbacktrace vendored. Use 0.11.2.

Fixed

• Fixed issues preventing builds on macOS.

[0.11.0] - 2025-12-27

Added

• RDoc documentation is now online - osyoyu.github.io/pf2/

• Native stack consolidation now supports LTO-ed binaries (@hanazuki)

Changed

• Pf2c module is now completely removed. Pf2c::Session has been merged as Pf2::Session.

Fixed

• Fixed an bug where the program crashes when a Pf2::Session is GC’d before profiling starts.

• Fixed an bug where the program crashes when the native stack was more than 200 frames deep.

[0.10.0] - 2025-12-26

Added

This version contains a complete rewrite of the profiler!

• The default sample collection backend has been switched to the new C-based backend.

• The previous Rust-based backed has been removed. Use v0.9.0 if you need it.

• macOS / non-Linux platform support!

• On platforms which lack timer_create(3) such as macOS, Pf2 now fall backs to setitimer(3) based sampling. This mode does not support per-thread CPU time sampling.

Changed

• logger is now declared as a dependency (Ruby 4.0 compat).

[0.9.0] - 2025-03-22

Added

• pf2 annotate command

• A new sample collection backend implemented in C

Changed

• Set SA_RESTART flag to reduce EINTRs in profiled code

[0.8.0] - 2025-01-27

Added

• The new serializer (Ser2) is now available in Pf2::Session#start through the use_experimental_serializer option.

• This serializer is more efficient and has a smaller memory footprint than the default serializer.

• Ser2 still lacks some features, such as weaving of native stacks.

[0.7.1] - 2025-01-02

Fixed

• Reverted Cargo.lock version to 3 to support older versions of Rust (<1.78).

[0.7.0] - 2025-01-03

Changed

• Prepended frozen_string_literal: true to all Ruby files.

• Internals

• Updated rb-sys to 0.9.105.

• Synced libbacktrace with upstream as of 2024-08-06.

[0.6.0] - 2024-07-15

Changed

• The default sampling interval is now 9 ms (was originally 49 ms).

• It is intentional that the default is not 10 (or 50) ms - this is to avoid lockstep sampling.

• BREAKING: Pf2::Reporter has been moved to Pf2::Reporter::FirefoxProfiler.

• This is to make space for other planned reporters.

[0.5.2] - 2024-07-13

Fixed

• Properly default to TimerThread scheduler on non-Linux environments.

[0.5.1] - 2024-03-25

Fixed

• Fixed compilation on non-Linux environments.

[0.5.0] - 2024-03-25

Added

• pf2 serve subcommand

• pf2 serve -- ruby target.rb

• Profile programs without any change

• New option: threads: :all

• When specified, Pf2 will track all active threads.

• threads: nil / omitting the threads option has the same effect.

• Introduce Pf2::Session (github.com/osyoyu/pf2/pull/16)

• Session will be responsible for managing Profiles and Schedulers

Removed

• Pf2::SignalScheduler and Pf2::TimerThreadScheduler are now hidden from Ruby.

• track_all_threads option is removed in favor of threads: :all.

[0.4.0] - 2024-03-22

Added

• New option: track_all_threads

• When true, all Threads will be tracked regardless of the threads option.

Removed

• The track_new_threads option was removed in favor of the track_all_threads option.

[0.3.0] - 2024-02-05

Added

• Native stack consolidation

• Pf2 now records native (C-level) stacks during sample capture.

  • This functionality is based on libbacktrace.

• New configuration interface for Pf2.start, Pf2::SignalScheduler.start, Pf2::TimerThreadScheduler.start

• They now accept keyword arguments (interval_ms, threads, time_mode, track_new_threads).

• New configuration options

• interval_ms: The sampling interval.

• time_mode (:wall or :cpu): The sampling timer’s mode. :wall is wall-clock time (CLOCK_MONOTONIC to be specific), :cpu is per-thread CPU time (CLOCK_THREAD_CPUTIME_ID).

Removed

• Configuration through positional arguments is no longer supported.

[0.2.0] - 2024-01-21

• New Ruby interface: Pf2.start, Pf2.stop, Pf2.profile

• Introduce the concepts of Schedulers

• Implement SignalScheduler and TimerThreadScheduler

• Rewritten many components

[0.1.0] - 2023-10-04

• Initial release