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Mohammad Waseem
Mohammad Waseem

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Scaling Load Testing Using Cost-Effective API Strategies

#loadtesting #api #automation

Addressing Massive Load Testing with Zero Budget Through Innovative API Development

Handling massive load testing is a common challenge for QA teams, especially when budget constraints limit access to expensive tools or infrastructure. As a Lead QA Engineer, I discovered that a strategic approach to API development can dramatically improve load testing capabilities without incurring extra costs. This post shares the methodology and technical insights into how leveraging lightweight APIs can enable scalable load testing.

The Core Challenge

The primary goal was to simulate high concurrent user activity to evaluate system performance under stress. Traditional load testing tools either became cost-prohibitive or lacked the flexibility to target specific endpoints efficiently. The need was for a bespoke, scalable solution that allowed for detailed control over load patterns without additional infrastructure.

Conceptual Shift: API as a Load Generator

Instead of relying on external tools, we repurposed existing backend APIs as load generators. By designing simple, purpose-built APIs that could mimic user behavior and generate high concurrency, we could create a controlled load environment. These APIs act as traffic amplifiers, designed to send a large volume of requests to the system.

Here is a simplified example of the API we built using Node.js with Express:

const express = require('express');
const app = express();
const port = 3000;

app.get('/load-test', (req, res) => {
  // Optional: introduce a small delay to simulate real user behavior
  setTimeout(() => {
    res.send({ status: 'ok', timestamp: Date.now() });
  }, 10); // 10ms delay
});

app.listen(port, () => {
  console.log(`Load test API listening on port ${port}`);
});
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This API endpoint /load-test can be invoked multiple times in parallel to generate substantial load.

Scaling Through Concurrency

To simulate high concurrency, we utilized simple scripting techniques. For instance, a Bash script with curl commands can rapidly spawn a large number of requests:

for i in {1..10000}
do
  curl -s http://localhost:3000/load-test &
done
wait
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This approach is cost-free, relying solely on existing infrastructure and open-source tools.

Enhancing Load Distribution

To distribute load more evenly or simulate different usage patterns, we integrated a basic dispatcher script:

#!/bin/bash
CONCURRENCY=1000
REQUESTS_PER_THREAD=10
TOTAL_THREADS=$((CONCURRENCY / REQUESTS_PER_THREAD))

for i in $(seq 1 $TOTAL_THREADS)
do
  for j in $(seq 1 $REQUESTS_PER_THREAD)
  do
    curl -s http://localhost:3000/load-test &
  done
  wait
done
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Adjusting CONCURRENCY and REQUESTS_PER_THREAD allows for flexible, cost-effective load scaling.

Monitoring and Results Analysis

Because the load is generated via simple APIs and scripts, integrating logging and monitoring is straightforward. We built lightweight logging endpoints to gather system response times, error rates, and throughput metrics:

app.get('/metrics', (req, res) => {
  // Collect and send metrics data
  // In practice, integrate with existing monitoring tools or log files
  res.send({
    timestamp: Date.now(),
    requests: globalRequestCount,
    errors: globalErrorCount,
    averageResponseTime: calculateAverageRT()
  });
});
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This setup provides continuous feedback, enabling analysis without expensive commercial monitoring solutions.

Outcomes and Takeaways

  • Cost-Effective: Fully reliant on open-source tools and existing infrastructure.
  • Customizable: APIs can be tailored to mimic real-world traffic patterns.
  • Scalable: Scripting enables rapid adjustment of load levels.
  • Insightful: Lightweight metrics collection helps identify bottlenecks.

By thinking creatively about leveraging the system’s own APIs as load generators, QA teams can perform extensive load testing without additional financial investment. This approach ensures system robustness and scalability, aligning with organizational constraints while maintaining quality standards.

Remember: The key to success in zero-budget load testing is simplicity. Use minimal, effective tools, automate wherever possible, and constantly monitor to derive actionable insights.

Happy testing!

🛠️ QA Tip

Pro Tip: Use TempoMail USA for generating disposable test accounts.

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