[hankaihong1]

Summary of Changes

This release addresses concurrency code smells and architectural bottlenecks across 8 components in multiloop, establishing formal state-machine invariants, thread safety under Python 3.14t (Free-Threaded / No-GIL), and bumping the version to v0.1.3:

1. AsyncRWMutex Concurrency Data Race Fix (src/multiloop/rwlock.py):
   • Synchronized _reader_depth and _writer_task with self._depth_lock = threading.Lock().
   • Moved _wake_all() calls outside of the depth lock to prevent deadlocks.
2. Native Synchronous Channel Communication (src/channel.rs & src/multiloop/primitives.py):
   • Replaced busy-spin polling (time.sleep(0.0005)) with native parking_lot::Condvar in RawAsyncChannel.
   • Automatically releases the Python GIL via py.detach() during blocking waits.
   • Added ReceiveChannel.recv_sync(timeout=None).
3. Dispatcher & Metrics Optimization (src/metrics.rs & src/pool.rs):
   • Added AtomicMetrics.add_global_pull(usize) for single atomic updates during batch pulls.
   • Upgraded NativeWorkerPool.metrics to parking_lot::RwLock.
4. Cross-Language Exception Hierarchy Standardization (src/lib.rs, src/multiloop/exceptions.py, src/multiloop/pool.py):
   • Exported ThreadPoolClosedError directly from PyO3 Rust extension.
   • Unified Python exception inheritance hierarchy and removed _RustPoolClosedError split.
5. O(1) Waiter Unregistration & Short-Circuit Removal (src/multiloop/_channel_base.py & src/channel.rs):
   • Enforced $O(1)$ removals in _discard_waiter via OrderedDict.pop().
   • Applied short-circuit pointer comparisons in Rust waiter unregistration.
6. GC Finalizer Safety Governance (src/multiloop/primitives.py & tests):
   • Eliminated self._wg.done() inside _TrackedCoroutine.__del__ to prevent cross-thread deadlocks under multi-threaded GC.
   • Emits RuntimeWarning when unawaited coroutines leak.
7. Event-Driven Dispatching & Drain Barrier (src/multiloop/pool.py):
   • Replaced 50ms polling loops in _worker_dispatcher with pure event-driven notify_event.wait().
   • Implemented self._drain_barrier = threading.Condition(self._lock) for graceful shutdown.
8. Cross-Loop Structured Concurrency (src/multiloop/_taskgroup.py & src/multiloop/context.py):
   • Added pool support to TaskGroup with isolated per-task child CancelScope instances.
   • Implemented remote drain barrier on context exit, bidirectional cascading cancellation, and unified ExceptionGroup aggregation.
   • Unified AsyncContext.task_group(pool=...) lifecycle tracking and automatic cascading cancellation.
9. Documentation, Type Stubs & Version Bump:
   • Full docstrings and Rustdoc comments updated across all modified files.
   • Synchronized __init__.pyi type stubs.
   • Aligned English and Chinese documentation (docs/API.md ↔ docs/API_ZH.md).
   • Bumped version to v0.1.3.

Verification

• Rust Core Tests: 23 passed.
• Python Tests: 341 passed (100%).
• Documentation consistency tests (tests/test_docs.py): 5 passed.
• All gates in make lint clean (ruff, mypy strict, pyright, clippy, cargo fmt).