[Unreleased]

[0.14.0] - 2026-01-25

Added

• Pf2.profile can now directly write a Firefox Profiler-compatible profile into a file or an IO-ish object. Check out Pf2.profile‘s out: and format: option.

• An experimental pprof-compatible recorder has been added. Profiles generated by this reporter can be passed to tools such as go tool pprof, or services such as Grafana Pyroscope or Google Cloud’s Cloud Profiler.

Changed

• Pf2::Reporter::FirefoxProfilerSer2 now emits a JSON string, not a Hash. Parse the JSON to obtain the original representaion.

Fixed

• Fixed a crash when a delayed SIGPROF is received after Pf2.stop is called.

[0.13.0] - 2026-01-18

Added

• Pf2 should now have a dramatically lower memory footprint.

• Samples are now stored in a compact hashmap internally.

• See github.com/osyoyu/pf2/pull/85 for details.

Fixed

• pf2 serve command now properly works. (Thanks @hanazuki)

[0.12.0] - 2026-01-09

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