# Logger & Monitor

## Overview

Effective logging and performance monitoring are crucial aspects of any web application. PHP-Fast provides a built-in `Logger` class for capturing important log messages such as **errors, warnings,** and **informational messages** and a `Monitor` class for measuring **execution time, memory usage,** and **CPU load** to help optimize performance.

## Logger

The Logger library allows you to record messages in different log levels. All logs are saved in:\
`writeable/logs/logger.log`

```php
Logger::info('This is an informational message.'); // Log informational message
Logger::warning('This is a warning message.');     // Log warning message
Logger::error('This is an error message.');        // Log error message
```

The `Logger` class supports optional parameters for file name and line number, making it easier to pinpoint issues.

## Monitor

```php
use System\Libraries\Monitor;

// Call Monitor class
$performance = Monitor::endFramework();

// Format memory usage
$formattedMemory = Monitor::formatMemorySize($performance['memory_used']);

// Print results
echo "Execution Time: " . round($performance['execution_time'], 5) . " seconds <br>";
echo "Memory Used: " . $formattedMemory . "<br>";
echo "CPU Load: " . $performance['cpu_usage'] . "<br>";

// Output:
Execution Time: 0.01095 seconds
Memory Used: 512 KB
CPU Load: 0.32

// Note: Check your constant DEBUG_TIME is 'true'
```

{% hint style="success" %}
Conclusion

The **Logger** and **Monitor** libraries in PHPFast make it easy to track your application's activity, detect issues, and improve performance. **Logger** helps record errors, warnings, and important messages, while **Monitor** measures execution time, memory usage, and CPU load, allowing developers to identify and fix problems efficiently.
{% endhint %}