Unexpected Performance Anomalies Across Dev, QA, and Prod Environments

The performance discrepancies you're experiencing across different environments can be attributed to several factors. Here are some potential causes and solutions to investigate:

1. Hardware and Instance Types

• Dev: Vagrant (local machine) with 2GB RAM and local MySQL.
• QA: AWS t2.micro with 1 CPU, 1GB RAM, and RDS db.t3.micro.
• Prod: AWS t3a.medium with 2 CPUs, 2GB RAM, and RDS db.t4g.small.

The differences in hardware and instance types can significantly impact performance. For example, the t2.micro and t3a.medium instances have different CPU credits and burst capabilities, which can affect performance under load.

2. Database Latency

• Dev: Local MySQL database.
• QA and Prod: AWS RDS instances.

Network latency between your application server and the RDS instance can introduce delays. Ensure that the RDS instances are in the same region as your application servers to minimize latency.

3. PHP and Laravel Versions

• Dev and QA: PHP 8.3, Laravel 11.
• Prod: PHP 8.1, Laravel 9.

Different PHP and Laravel versions can have performance implications. PHP 8.3 and Laravel 11 might have optimizations that are not present in PHP 8.1 and Laravel 9.

4. Configuration Differences

Even though you are using Ansible playbooks, there might be subtle configuration differences. Ensure that:

• All environments have the same PHP configurations (e.g., opcache, memory_limit).
• Database configurations (e.g., connection pooling, query caching) are consistent.

5. Resource Limits and Throttling

AWS instances, especially smaller ones like t2.micro, can be subject to CPU throttling. Check the CloudWatch metrics for CPU credits and throttling.

6. Benchmarking Methodology

The benchmarking function you provided is a good start, but consider the following improvements:

• Warm-up Runs: Perform a few warm-up runs before measuring to account for JIT compilation and caching.
• Isolate Tests: Run each test in isolation to avoid interference from other processes.

Improved Benchmarking Function

Here's an improved version of your benchmarking function:

function testPerformance($callback, $tries = 10) {
    $totalTime = 0;

    // Warm-up runs
    for ($i = 0; $i < 5; $i++) {
        $callback();
    }

    for ($i = 0; $i < $tries; $i++) {
        $startTime = microtime(true);

        $callback();

        $endTime = microtime(true);
        $executionTime = $endTime - $startTime;
        $totalTime += $executionTime;
    }

    return $totalTime / $tries;
}

Example Usage

echo testPerformance(fn () => DB::table('users')->where('id', 2)->get(), 100000);
echo testPerformance(fn () => array_sum(range(1, 100000)), 100000);
echo testPerformance(fn () => Route::dispatch(Request::create('/login', 'GET')), 10000);

Additional Recommendations

1. Profiling Tools: Use profiling tools like Blackfire or Xdebug to identify bottlenecks.
2. Database Indexes: Ensure that your database queries are optimized and that appropriate indexes are in place.
3. Caching: Implement caching strategies (e.g., query caching, route caching) to improve performance.

By systematically addressing these areas, you should be able to identify and mitigate the performance issues across your environments.