Loadr

A lightweight REST load testing tool with flexible request patterns, token auth, and detailed performance metrics output.

Stack

• Core: Pure Golang
• Output: Console + CSV/TXT reporting
• Pattern support: Sequential and probabilistic request patterns
• Transport: Standard Go HTTP client

Requirements

• Golang 1.23.x or higher

Installation

go build

Quick Start

# Simple pattern: 5 POST requests at 20 req/sec
./loadr -rate=20 -max=100 -url=http://api.example.com -pattern=5p

# Mixed pattern: 1 POST followed by 5 GETs, repeating
./loadr -rate=20 -max=100 -url=http://api.example.com -pattern=1p5g

# Probabilistic pattern: 20% POSTs, 80% GETs
./loadr -rate=20 -max=100 -url=http://api.example.com -pattern=20%p80%g

# With auth and request body
./loadr -rate=20 -max=100 -url=http://api.example.com -pattern=2p3g -json=./data.json -token=YourBearerToken

Request Patterns

The -pattern flag supports three types of request patterns:

Simple Patterns

• 5p : 5 POST requests
• 3g : 3 GET requests
• Default is 1g if no pattern specified

Sequential Patterns

• 1p5g : 1 POST followed by 5 GETs, repeating
• 2p3g : 2 POSTs followed by 3 GETs
• 3g2p : 3 GETs followed by 2 POSTs

Probabilistic Patterns

• 20%p80%g : Random selection with 20% POST and 80% GET probability
• Percentages must sum to 100

Command Line Flags

-rate     Number of requests per second (default: 10)
-max      Maximum number of requests to send (default: 50)
-url      Target URL (default: "https://example.com")
-pattern  Request pattern (e.g., "5p", "1p5g", "20%p80%g")
-json     Path to JSON file for request body
-token    Bearer token for authorization
-v        Print version information

Performance Metrics

Loadr generates two types of reports:

Summary Report (.reports/summary_[timestamp].txt)

• Total requests sent/received
• Average, maximum, and minimum latency
• Requests/sec (target and actual)
• Latency percentiles (p50, p95, p99)
• Pattern information

Detailed CSV (.reports/detailed_metrics_[timestamp].csv)

• Per-request timestamps
• Individual request latencies
• Status codes
• Request types

Technical Details

Rate Limiting

Loadr uses a time-based approach to approximate the target requests per second:

1. Calculates ideal interval between requests: interval = 1second / requestsPerSecond
2. Tracks next scheduled request time
3. Uses sleep to maintain timing between requests
4. Launches requests asynchronously to maintain timing accuracy

Request Execution

• Uses a global HTTP client for connection reuse
• Requests are executed concurrently using goroutines
• Metrics are updated synchronously using mutex protection

Metrics Collection

• Real-time tracking of request latencies
• Thread-safe counters for requests and responses
• Calculates percentiles from stored request durations
• Support for detailed CSV export for external analysis

Note: The actual request rate may vary slightly from the target rate due to system load and network conditions. The detailed CSV output can be used to analyze the actual timing distribution.