Stress Test

tools/Moongate.Stress is a black-box load testing tool that spawns real UO TCP clients against a live Moongate server. It validates login flow, enters the game world, runs a continuous movement loop, and evaluates Service Level Objectives (SLOs).

Test Flow

The test runs in five phases:

Phase 1: User Bootstrap

The tool ensures test accounts exist before connecting. It calls the HTTP API to create accounts with format {prefix}_{index:0000} (e.g. stress_0001, stress_0002, ...).

  • Fetches existing users via GET /api/users/
  • Creates missing accounts via POST /api/users/
  • If JWT is enabled, authenticates first via POST /auth/login with admin credentials

Phase 2: Ramp-up

Clients spawn gradually at the configured rate (--ramp-up-per-second). The delay between each client spawn is 1.0 / ramp-up-per-second seconds. The duration timer starts after all clients are launched.

Phase 3: Login

Each client executes the full UO login handshake:

  1. Connects to the login server (host:port)
  2. Sends login seed packet (0xEF)
  3. Sends account login packet (0x80) with username/password
  4. Receives server list (0xA8), sends server select (0xA0, index 0)
  5. Receives redirect packet (0x8C) with game server IP, port, and session key

Phase 4: Game Entry

After redirect, the client connects to the game server:

  1. Sends seed packet with session key
  2. Sends game login packet (0x91) with session key, username, password
  3. Sends login character packet (0x5D)
  4. If no login confirmation within 7 seconds, falls back to character creation (0xF8)
  5. Waits for login confirmation (0x1B) within a 10-second deadline
  6. On failure, marks login as failed

Phase 5: Movement Loop

Each logged-in client enters a continuous movement loop until the test duration expires:

  1. Sends a random directional movement packet (0x02) with a running flag and incrementing sequence number
  2. Waits up to 1500ms for the movement ACK packet (0x22) matching the sequence
  3. Records the ACK latency using Stopwatch.GetTimestamp() precision timing
  4. Waits --move-interval-ms then sends the next move

CLI Options

Flag Default Description
--host 127.0.0.1 Server hostname
--port 2593 Login server port (1-65535)
--http http://localhost:8088 HTTP API base URL for user bootstrap
--clients 100 Number of concurrent stress clients (1-10,000)
--duration 300 Test duration in seconds (10-86,400)
--ramp-up-per-second 10 Clients to spawn per second (1-10,000)
--move-interval-ms 300 Delay between moves per client in ms (50-10,000)
--user-prefix stress Username prefix for test accounts
--user-password StressPwd#123 Password for all test accounts
--user-role Regular Account role (Regular, Counselor, GameMaster, Administrator)
--admin-username (none) Admin username for JWT authentication
--admin-password (none) Admin password for JWT authentication
--verbose false Enable verbose per-client logging

Run

Quick local test with 10 clients for 30 seconds:

dotnet run --project tools/Moongate.Stress -- \
  --host 127.0.0.1 --port 2593 \
  --http http://localhost:8088 \
  --clients 10 --duration 30 --ramp-up-per-second 5

Full 100-client run:

dotnet run --project tools/Moongate.Stress -- \
  --host 127.0.0.1 --port 2593 \
  --http http://localhost:8088 \
  --clients 100 --duration 300 --ramp-up-per-second 10

With JWT-enabled HTTP API:

dotnet run --project tools/Moongate.Stress -- \
  --host 127.0.0.1 --port 2593 \
  --http http://localhost:8088 \
  --clients 100 --duration 300 \
  --admin-username admin --admin-password your_password

Service Level Objectives (SLOs)

The tool evaluates these SLOs at the end of the run. The process exits with code 0 on pass, 1 on failure.

SLO Threshold
Login success rate >= 99%
Unexpected disconnects 0
Movement ACK p95 latency < 200ms
Minimum ACKs received >= 1

All conditions must pass for the test to succeed.

Metrics Collected

Metric Description
totalClients Number of configured clients
loginSucceeded Successful login count
loginFailed Failed login count
unexpectedDisconnects Premature disconnection count
movesSent Total movement packets sent
movesAcked Total movement ACK packets received
ackLatencyP50Ms 50th percentile ACK latency (ms)
ackLatencyP95Ms 95th percentile ACK latency (ms)
ackLatencyP99Ms 99th percentile ACK latency (ms)
durationSeconds Actual test duration

Latency is measured per-packet using Stopwatch.GetTimestamp() for high-precision timing. Percentiles are computed from the full sorted latency distribution at the end of the run.

Output

The tool produces two outputs:

Console summary: prints all metrics, SLO evaluation results, and pass/fail status.

JSON artifact: written to artifacts/stress/latest.json:

{
  "metrics": {
    "totalClients": 100,
    "loginSucceeded": 100,
    "loginFailed": 0,
    "unexpectedDisconnects": 0,
    "movesSent": 98200,
    "movesAcked": 98195,
    "ackLatencyP50Ms": 2.1,
    "ackLatencyP95Ms": 8.4,
    "ackLatencyP99Ms": 15.2,
    "durationSeconds": 300
  },
  "passed": true,
  "failedConditions": []
}

Implementation Details

The stress client speaks real UO protocol:

  • Packet writers for all login/movement opcodes (0x80, 0x91, 0xEF, 0x5D, 0xF8, 0x02, 0xA0)
  • Huffman decompression for server responses (256-entry encoding table with variable-length codes)
  • Character creation fallback: if no existing character is found, the client creates a default male human on Trammel with base stats (STR 60, DEX 50, INT 40)
  • Thread-safe metrics: uses Interlocked operations, ConcurrentDictionary, and ConcurrentQueue for lock-free collection

Notes

  • This is a practical operational stress test, not a micro-benchmark.
  • Run on the same network profile you want to validate (localhost, LAN, or staging).
  • Start with short runs (--clients 10 --duration 30) before scaling to 100+ clients.
  • The tool does not test game logic beyond movement. It validates server stability under concurrent connection and packet load.

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