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PHP Intermediate 268 views

Allowed Memory Size Exhausted

A script tried to allocate more memory than the allowed memory limit.

Explanation

Allowed memory size exhausted occurs when a PHP script tries to use more memory than the memory_limit setting allows. The default is typically 128MB or 256MB. This commonly happens when loading large files into memory, processing large datasets without pagination, creating large arrays, or when memory leaks cause gradual memory consumption. PHP terminates the script when the limit is reached.

Common Causes

  • Loading large files into memory
  • Processing large datasets at once
  • Memory leaks in code
  • Creating large arrays or objects
  • Recursive function consuming stack memory

Solution

Increase the memory_limit in php.ini if the operation legitimately requires more memory. Optimize code to use less memory: process data in chunks, use generators instead of arrays, unset variables after use, and avoid creating unnecessary copies. Use Laravel's chunk() and cursor() methods for database queries. Profile memory usage with xdebug or memory_get_usage() to find memory-intensive operations. For file processing, use SplFileObject or fopen/fread instead of file_get_contents for large files.

Code Example 

// Loading entire file into memory - can exhaust memory
$content = file_get_contents('large_file.csv'); // 500MB file

// Fix: process line by line
$handle = fopen('large_file.csv', 'r');
while (($line = fgetcsv($handle)) !== false) {
    processLine($line);
}
fclose($handle);

// Check current usage
echo memory_get_usage() . ' bytes used';
echo memory_get_peak_usage() . ' peak bytes';

// Increase in php.ini
memory_limit = 512M

Error Information

Language

php

Difficulty

Intermediate

Views

268

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