What tools and methods do you use for debugging and profiling PHP applications?

For debugging, I use Xdebug, which allows setting breakpoints, viewing call stacks, variable values, and executing code step-by-step.

For profiling, I also use Xdebug in conjunction with visualization tools such as KCachegrind or Webgrind. This helps analyze function execution times and identify "bottlenecks".

Additionally, I use:

• Logging: Writing informative logs with execution context to track issues in asynchronous processes or in production.
• Built-in PHP functions: var_dump(), print_r() for quick content inspection of variables.
• Browser debugger: For analyzing request headers, responses, and network activity.
• Performance monitoring systems: For aggregated metric collection and anomaly detection in production (e.g., New Relic, Sentry).

Methodologies:

• Step-by-step debugging: Using Xdebug to reproduce issues and analyze application state at specific moments.
• "Divide and conquer" principle: Isolating problematic code sections to simplify debugging.
• Logging with different levels of detail: Using various log levels (DEBUG, INFO, WARNING, ERROR) depending on the criticality of the information.
• Testing: Writing unit tests and integration tests to detect errors early in development.

Example of using var_dump():

<?php
// Debugging example with var_dump()
$data = ['a' => 1, 'b' => [2, 3]];
var_dump($data);
// Outputs:
// array(2) {
//   ["a"]=>
//   int(1)
//   ["b"]=>
//   array(2) {
//     [0]=>
//     int(2)
//     [1]=>
//     int(3)
//   }
// }
?>