# urus-bench

HTTP/1.1 performance benchmarks comparing **Urus** (actor-based Rust web framework) against **Axum** (async/await Rust via hyper). Designed to test the Urus spec claim: "**within 2× of Axum RPS**."

## Overview

This benchmark suite measures throughput (RPS) and tail latency (p99) across four scenarios of increasing complexity:

| Scenario | Workload | Framework Test |
|----------|----------|---|
| **S1** | Bare HTTP (`GET /ping`) | Protocol + connection handling |
| **S2** | Routing + middleware | Logger, request ID, auth, router |
| **S3** | In-memory store (mixed) | Message-passing vs. mutex contention |
| **S4** | SQLite (mixed) | Database overhead under actor model |

Full specification: see [`urus-bench-spec.md`](./urus-bench-spec.md).

## Quick Start

### Prerequisites

- Rust 1.70+ (stable)
- `wrk` and `wrk2` (load generators)
- `pidstat`, `taskset` (process introspection & CPU pinning)
- `curl` (sanity checks before benchmarks)

**Recommended**: Use the provided `nix-shell`:
```bash
nix-shell
```

This installs all dependencies except Rust (assumed already on your host).

### Build

```bash
cargo build --release
```

Both `urus-server` and `axum-server` will be built. Runs take ~5–10 minutes total (30s warmup + 60s measure per scenario).

### Run a Single Benchmark

```bash
./runner.sh urus-mem s1
```

This runs Urus on scenario S1, pins the server to cores 0–7, the load generator to cores 8–15, and saves results to `results/<batch>/<server>-<scenario>/`.

### Run the Full Matrix

```bash
./run_all.sh
```

Runs 8 benchmarks (Urus + Axum on S1–S3, both on SQLite S4). Outputs a summary table and machine-readable JSON index.

### Quick Mode (for development)

```bash
./run_all.sh --quick
```

Uses 15s warmup + 15s measure (instead of 30+60) for faster iteration.

## Repository Structure

```
urus-bench/
├── urus-server/          # Urus implementation (actor-based)
│   ├── src/
│   │   ├── main.rs
│   │   ├── handlers.rs
│   │   ├── middleware.rs
│   │   └── store.rs      # In-memory and SQLite store actors
│   └── Cargo.toml
├── axum-server/          # Axum implementation (async/await + hyper)
│   ├── src/
│   │   └── main.rs
│   └── Cargo.toml
├── loadgen/              # wrk2 scripts
│   ├── common.lua        # shared headers, bearer token
│   ├── s1_ping.lua       # simple GET
│   ├── s2_user_get.lua   # router + middleware
│   └── s3_mixed.lua      # 80% GET, 15% list, 5% POST
├── runner.sh             # Single-run orchestrator
├── run_all.sh            # Full-matrix orchestrator
├── urus-bench-spec.md    # Detailed specification
├── shell.nix             # Nix environment
├── Cargo.toml            # Workspace definition
└── results/              # Output (created at runtime)
    └── <batch>/
        ├── summary.md    # Headline results
        ├── index.json    # Machine-readable results
        └── <server>-<scenario>/
            ├── result.json      # Metrics: RPS, latencies, CPU, RSS
            └── histogram.txt    # HDR histogram (wrk2 raw output)
```

## Key Scripts

### `runner.sh`

Runs a single (server, scenario) pair. Usage:

```bash
./runner.sh [--help] <server> <scenario> [options]

# Examples:
./runner.sh urus-mem s1               # Urus on S1 (defaults)
./runner.sh axum-sqlite s4            # Axum on S4
./runner.sh urus-mem s3 --quick       # Urus on S3, short timings
./runner.sh axum-mem s2 --measure-sec=120  # Extended measurement
```

**Server names:**
- `urus-mem`, `axum-mem` (in-memory store)
- `urus-sqlite`, `axum-sqlite` (SQLite store)

**Scenario names:**
- `s1`, `s2`, `s3`, `s4` (see Specification, below)

**Key options:**
- `--quick`: Use 15s warmup + 15s measure (fast iteration)
- `--measure-sec=N`: Set measurement duration
- `--warmup-sec=N`: Set warmup duration
- `--wrk-conns=N`: Number of connections (default 256)
- `--wrk-threads=N`: Load generator threads (default 8)
- `--batch=ID`: Tag for results directory (default: timestamp)

Output: `results/<batch>/<server>-<scenario>/result.json` + `histogram.txt`.

### `run_all.sh`

Runs the full benchmark matrix. Usage:

```bash
./run_all.sh [options]

# Examples:
./run_all.sh                   # Full 8-run matrix
./run_all.sh --quick           # Full matrix, 15s+15s timings
./run_all.sh --scenarios=s1,s2 # Only S1 and S2
./run_all.sh --servers=urus-mem,axum-mem  # Only in-memory
```

**Output:** 
- `results/<batch>/summary.md` — headline table (text)
- `results/<batch>/index.json` — structured results (machine-readable)

## Configuration

Environment variables (passed through to `runner.sh`):

| Variable | Default | Purpose |
|----------|---------|---------|
| `WARMUP_SEC` | 30 | Warm-up duration (TCP window scaling, JIT) |
| `MEASURE_SEC` | 60 | Measurement duration (where latencies are sampled) |
| `PROBE_SEC` | 30 | Saturation probe duration (closed-loop `wrk`) |
| `SERVER_CPUS` | 0-7 | CPU cores pinned to server process |
| `LOADGEN_CPUS` | 8-15 | CPU cores pinned to load generator |
| `WRK_CONNS` | 256 | Concurrent connections |
| `WRK_THREADS` | 8 | Load generator thread count |
| `SAT_RATIO` | 0.7 | Target RPS = saturation × this ratio |
| `BEARER` | (required) | Authorization token for auth middleware |

Example:
```bash
MEASURE_SEC=120 WARMUP_SEC=60 ./runner.sh urus-mem s3
```

## Interpreting Results

### Metrics

Each run produces `result.json` with:

- **`sustained_rps`** — requests/second at the target rate (wrk2 measurement)
- **`p99_latency_ms`** — 99th percentile latency (HDR histogram)
- **`server_cpu_pct`** — average CPU utilization (pidstat)
- **`server_rss_mb`** — peak resident set size
- **`handler_p99_us`** — server-side handler latency (p99, microseconds)

### Reading the Output

```
========== [1/8] urus-mem     s1  ==========
       sustained=54640.68 rps   p99=2.70ms
```

This is Urus on S1: **54,640 RPS at sustained load, with p99 latency of 2.70ms.**

### Comparing Frameworks

The spec target is **Urus RPS ≥ 50% of Axum RPS** on S1 and S2. Example:

- Urus S1: 54,640 RPS
- Axum S1: 288,330 RPS
- Ratio: 0.19 (54,640 / 288,330) → **FAIL** (need ≥ 0.50)

## Development & Debugging

### Running a Single Server in Isolation

```bash
cargo run --release --bin urus-server -- --store=memory
# Server listens on 127.0.0.1:8080
curl -H "Authorization: Bearer test-token-aaaaaaaaaaaaaaaaaaaa" \
  http://127.0.0.1:8080/ping
# Response: 200 OK, body "pong"
```

### Inspecting SQLite Between Runs

```bash
sqlite3 urus.db "SELECT COUNT(*) FROM users;"
```

SQLite databases are created in the working directory as `urus.db` (Urus) and `axum.db` (Axum).

### Profiling a Run

Modify `runner.sh` to include `perf record`:

```bash
perf record -g -F 99 -p $pid -- ...  # during the measurement phase
perf report
```

### Viewing Raw Histograms

```bash
cat results/<batch>/<server>-<scenario>/histogram.txt
# HDR histogram format (wrk2 output)
```

Convert to a plot with `hdr-plot` (wrk2 companion tool) or similar.

## Known Limitations

- **No TLS**: HTTP/1.1 plaintext only. TLS would require additional tooling per framework.
- **Loopback only**: All networking is on 127.0.0.1 (generous environment). Real-world RTT / packet loss not tested.
- **No pipelining**: HTTP/1.1 pipelining not exercised.
- **No Cowboy**: BEAM reference removed; focus is Urus vs. Axum.

## Results from 2026-05-26

Summary from the last full run (batch `20260526-220625`):

| | Urus | Axum | Ratio |
|---|------|------|-------|
| **S1 RPS** | 54,640 | 288,330 | 0.19 (5.3×) |
| **S2 RPS** | 53,139 | 315,596 | 0.17 (5.9×) |
| **S3 RPS** | 53,616 | 316,342 | 0.17 (5.9×) |
| **S4 RPS** | 52,590 | 320,150 | 0.16 (6.1×) |

**Verdict:** Urus fails the "within 2×" spec target on throughput. Tail latency (p99) remains sub-3ms under all loads; Axum's p99 scales with concurrency (11–60ms). See [`benchmark-report.html`](./benchmark-report.html) for full analysis.

## References

- **Specification**: [`urus-bench-spec.md`](./urus-bench-spec.md) — design principles, scenarios, pass/fail criteria
- **Latest Report**: `benchmark-report.html` — 2026-05-26 results & interpretation
- **Urus**: [smarm/urus](https://github.com/smarm/urus)
- **Axum**: [tokio-rs/axum](https://github.com/tokio-rs/axum)
- **wrk2**: [giltene/wrk2](https://github.com/giltene/wrk2) — constant-rate load generator

## License

Benchmark code is in the public domain or under your preferred permissive license (MIT/Apache-2.0). See individual crate licenses for dependencies.