microsoft/bocpy v0.5.0

v0.5.0

Repository: microsoft/bocpy

Tag: v0.5.0

Published: 2026-05-05T10:28:05Z

Prerelease: no

Release notes:

Highlights

This release delivers a Verona-RT-style work-stealing scheduler, a global noticeboard (shared key-value store), removal of the central scheduler thread in favour of direct dispatch, and a major C source refactor into per-subsystem translation units with a portable atomics layer.

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New Features

• Work-stealing scheduler — the single behavior queue is replaced with a distributed scheduler. Each worker owns an MPMC behavior queue, pops locally first, and steals from peers when idle. Idle workers park on per-worker condition variables and are signalled directly by producer/victim.
• Per-worker fairness tokens — a token node advances through each worker's queue so long-running behaviors cannot monopolise dispatch slots; also drives cooperative shutdown.
• Noticeboard — a shared key-value store (up to 64 keys) readable/writable without acquiring cowns. Writes are non-blocking; reads return a cached per-behavior snapshot. Includes notice_write, notice_read, notice_update, notice_delete, notice_sync, noticeboard_version, and the REMOVED sentinel.
• Distributed scheduler — two-phase locking, request linking, and dispatch run directly on the caller's thread in C; cown release runs on the executing worker. MCS-style intrusive linked list per cown for zero-bounce handoff.
• `Cown.exception` property — indicates whether the held value is from an unhandled exception.
• `compat.h` / `compat.c` portability layer — uniform BOCMutex, BOCCond, boc_atomic_*_explicit, monotonic-time, and sleep primitives across MSVC, pthreads, and C11 ``.
• `xidata.h` cross-interpreter shim — centralised _PyXIData_* / _PyCrossInterpreterData_* version ladders for CPython 3.12–3.15 (including free-threaded builds).
• `fanout_benchmark` example — fan-out/fan-in benchmark exercising scheduler throughput under heavy producer load.
• Prime factor example (examples/prime_factor.py) — parallel factorisation via Pollard's rho with noticeboard-coordinated early termination.
• Benchmark harness (examples/benchmark.py) — micro-benchmarks for scheduling throughput, message-queue latency, and noticeboard contention.

Bug Fixes

• Transpiler aliased imports — visit_Import / visit_ImportFrom now track alias names (import X as Y), preventing spurious "name not found" errors and duplicate whencall injection.
• Global variable capture — @when closure capture falls back to frame.f_globals when a name is not in any local scope, fixing NameError for module-level variables.

Improvements

• In-memory transpiled-module loading — workers exec the transpiled source from a string literal instead of writing to disk, eliminating filesystem round-trips and leftover .py files.
• Nested `@when` capture — the transpiler recurses into nested @when-decorated functions when computing outer captures, so child behaviors can close over the outer frame.
• C extension split — _core.c reduced from ~5,000 to ~3,500 lines by extracting sched.{c,h}, noticeboard.{c,h}, terminator.{c,h}, tags.{c,h}, cown.h, compat.{c,h}, and xidata.h.
• Direct dispatch on cown release — behavior_release_all hands resolved successors directly to workers via boc_sched_dispatch, removing one queue hop per handoff.
• Cooperative worker shutdown — boc_sched_worker_request_stop_all / boc_sched_unpause_all provide a clean stop/drain protocol.
• Matrix docstrings — all Matrix C methods now carry built-in docstrings.
• Examples package relocated — moved to top-level examples/ directory (still importable as bocpy.examples).
• Filtered PyPI README — setup.py strips `` regions before publishing.
• Documentation refresh — expanded coverage of noticeboard, distributed scheduler, and new APIs.

Internal Test Modules (opt-in via BOCPY_BUILD_INTERNAL_TESTS=1)

• _internal_test_atomics — correctness tests for compat.h typed-atomics.
• _internal_test_bq — torture tests for the MPMC behavior queue.
• _internal_test_wsq — tests for work-stealing primitives (fast pop, slow pop, steal, park/unpark).

Test Suite

• test_noticeboard.py — snapshot semantics, notice_update atomicity, REMOVED, notice_sync, version monotonicity.
• test_scheduler_integration.py, test_scheduler_stats.py, test_scheduler_steal.py — end-to-end and per-primitive scheduler tests.
• test_compat_atomics.py — portable atomics smoke tests.
• test_stop_retry_composition.py — stop()/start()/wait() retry composition.
• test_scheduling_stress.py — expanded with fan-out, work-stealing, and shutdown stress scenarios.
• test_transpiler.py — AST extraction, capture rewriting, aliased imports, module export.

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Full changelog: v0.3.1...v0.5.0