Methods and Alternatives for Implementing Concurrent HTTP Requests in Postman

Technical Challenges of Concurrent Requests in Postman

In API development and testing, there is often a need to simulate scenarios where multiple clients send requests to a server simultaneously. According to high-scoring answers on Stack Overflow, the Postman Chrome extension does not natively support true concurrent request execution. While Postman provides a Runner feature that allows users to run multiple test cases through iterations and CSV data files, these requests are executed sequentially rather than in true parallel.

Functionality Analysis of Postman Runner

Postman Runner, as the built-in test executor, offers the following key features:

• Iteration settings: Users can specify the number of times tests are repeated
• Data file support: Supports uploading CSV format data files to provide parameterized data for different test runs
• Environment variable management: Allows running the same test collection in different environments
• Delay configuration: Supports setting time intervals between requests

However, as reported in Reference Article 1, even with minimal delay settings (such as 1ms), true concurrent execution cannot be achieved. Test results show that requests are still processed serially, which presents significant limitations for load testing scenarios that require simulating high concurrency.

Professional Concurrent Testing Tool: Apache JMeter

For scenarios requiring genuine concurrent request execution, Apache JMeter provides a complete solution. As a professional performance testing tool, JMeter offers the following advantages:

• Thread group configuration: Supports setting multiple virtual users to execute requests simultaneously
• Distributed testing: Enables coordinated work across multiple machines to simulate large-scale concurrency
• Rich listeners: Provides detailed performance metrics and graphical analysis
• Protocol support: Supports multiple protocols including HTTP, HTTPS, SOAP, and REST

JMeter's thread model allows users to precisely control the number of concurrent users, startup time, and duration, which is crucial for stress testing and load testing. For example, to simulate 500 users logging in simultaneously, you can configure a thread group with 500 threads in JMeter, with each thread independently executing authentication requests.

Alternative Approaches: Command Line Tools and Scripts

Beyond professional testing tools, command line utilities can be used to implement simple concurrent requests:

curl Asynchronous Requests

In Bash environments, multiple curl requests can be executed asynchronously using the & operator:

curl https://api.example.com/login -X POST -d '{"username":"user1","password":"pass1"}' &
curl https://api.example.com/login -X POST -d '{"username":"user2","password":"pass2"}' &
curl https://api.example.com/login -X POST -d '{"username":"user3","password":"pass3"}' &

While this approach is simple, it lacks effective management and analysis capabilities for test results.

Newman Parallel Execution

Postman's command line tool Newman, combined with Node.js, enables parallel execution of collections:

const path = require('path');
const async = require('async');
const newman = require('newman');

const parametersForTestRun = {
  collection: path.join(__dirname, 'postman_collection.json'),
  environment: path.join(__dirname, 'postman_environment.json')
};

const parallelCollectionRun = function(done) {
  newman.run(parametersForTestRun, done);
};

async.parallel([
  parallelCollectionRun,
  parallelCollectionRun,
  parallelCollectionRun
], function(err, results) {
  if (err) {
    console.error(err);
    return;
  }
  
  results.forEach(function(result) {
    const failures = result.run.failures;
    if (failures.length > 0) {
      console.info('Test failures:', JSON.stringify(failures, null, 2));
    } else {
      console.info(`${result.collection.name} ran successfully.`);
    }
  });
});

This approach leverages Node.js's asynchronous capabilities to execute multiple Postman collections in parallel within a single process.

Performance Comparison and Selection Recommendations

Different concurrent testing solutions show significant variations in usability, feature completeness, and performance:

• Postman Runner: Suitable for functional testing and simple integration testing, but not ideal for high-concurrency scenarios
• Apache JMeter: Professional performance testing tool, suitable for complex load testing and stress testing
• curl asynchronous requests: Quick validation of simple concurrent scenarios, but lacks test management capabilities
• Newman parallel execution: Lightweight concurrent solution based on existing Postman collections

Best Practice Recommendations

When selecting a concurrent testing solution, consider the following factors:

• Testing objectives: Clarify whether it's for functional verification or performance testing
• Concurrency scale: Choose appropriate tools based on actual requirements
• Resource constraints: Consider available hardware resources and time costs
• Team skills: Select tools that the team is familiar with and can maintain

For most enterprise applications, it's recommended to use professional performance testing tools like JMeter for formal load testing, while using Postman with scripts for preliminary concurrent validation during development phases.