# Changelog for thread-utils-context
## 0.4.1.0
- Fix space leak: repeated `attach`/`detach` on long-lived threads no longer
accumulates `Weak#` objects. Detach marks the slot key with a flag bit
instead of tombstoning, so re-attach reuses the slot without registering
a duplicate GC finalizer.
- Fibonacci multiplicative hash for slot assignment spreads sequential
thread IDs across cache lines, reducing false sharing under multi-core
contention.
- Detach no longer writes to the GC-traced value array, eliminating
card-table contention on the detach path.
- Hot-path `lookup`/`adjust`/`lookupRefFast` no longer check for detached
markers in the value array; the CMM probe reports detach status directly.
## 0.4.0.0
- Replace striped-IntMap internals with a flat open-addressed hash table
backed by per-thread IORefs. Reads and writes on the hot path are now
plain IORef operations, with zero CAS and zero contention.
- Add CMM primops (`stg_getCurrentThreadId`, `stg_probeThreadSlot`,
`stg_probeSlotByKey`) to eliminate ThreadId allocation and FFI overhead
on the hot path.
- New construction function: `newThreadStorageMapWith` for explicit capacity.
- New `getCurrentThreadId` reads `CurrentTSO.id` directly via CMM.
- New ref-based API for instrumentation hot loops: `ensureRef`,
`ensureRefFast`, `lookupRef`, `lookupRefFast`, `readRef`, `writeRef`,
`modifyRef`.
- Remove `containers` dependency.
- Requires `cabal-version: 3.0` (for `cmm-sources`).
- Backwards compatible: all previously exported symbols retain their
original type signatures.
## 0.3.0.4
- Fix compilation on GHC 8.12
## 0.3.0.3
- Fix compilation of purgeDeadThreads on GHC 9.6
## Unreleased changes