---
title: "HeliosProxy v0.3.1 Release Notes"
---

# HeliosProxy v0.3.1 Release Notes

HeliosProxy v0.3.1 is a maintenance release focused on connection-pool
correctness, lower hot-path overhead, and safer PostgreSQL wire parsing. It does
not remove APIs and does not add new feature modules.

## Highlights

- Connection-pool checkout avoids serializing per-node work through a global
  lock.
- Pool metrics use atomic counters, so metrics snapshots no longer contend with
  active checkouts.
- PostgreSQL prepared-statement parameter parsing avoids per-parameter heap
  allocation.
- L1 cache hits use a read path that permits concurrent readers of the same key.
- `max_connections` is enforced against in-use connections.
- Unterminated C-string protocol input returns a protocol error.

## Performance Notes

The figures below come from single-threaded sequential benchmark runs on the
same machine. They describe component-level pool behavior, not end-to-end query
throughput.

| Benchmark | v0.3.0 | v0.3.1 | Change |
|---|---:|---:|---:|
| `pool/acquire_release/single` | 471.81 ns | 329.83 ns | 30% faster |
| `pool/throughput/sequential_acquire/1` | 490.36 ns | 353.88 ns | 28% faster |
| `pool/throughput/sequential_acquire/10` | 5.354 us | 3.351 us | 37% faster |
| `pool/throughput/sequential_acquire/50` | 25.36 us | 16.95 us | 33% faster |
| `pool/metrics/read_metrics` | 35.90 ns | 11.51 ns | 68% faster |

## Compatibility

HeliosProxy v0.3.1 remains compatible with the v0.3 configuration surface,
feature flags, CLI behavior, admin API, Docker image layout, and module list.

## Upgrade Notes

Upgrade from v0.3.0 by replacing the proxy binary or container image with
v0.3.1. Existing `proxy.toml` files do not require migration.