Allowed Memory Size Exhausted

Why This Happens

PHP enforces a memory limit per script defined by the memory_limit directive in php.ini. When your script tries to allocate memory beyond this limit, PHP terminates it. This commonly happens when loading large datasets into memory, recursive functions without proper termination, or accumulating data in loops.

The Problem

// Loading millions of rows into memory at once
$rows = $pdo->query('SELECT * FROM logs')->fetchAll();
foreach ($rows as $row) {
    processRow($row);
}

The Fix

// Process rows one at a time using a cursor
$stmt = $pdo->query('SELECT * FROM logs');
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
    processRow($row);
}

Step-by-Step Fix

1. 1

   Identify the memory hog

   Check the line number in the error. Look for large array operations, file reads, or unbounded loops that accumulate data.

2. 2

   Optimize memory usage

   Use generators, chunked queries, streaming reads, or unset large variables after use to reduce peak memory consumption.

3. 3

   Increase the limit if needed

   If the memory usage is genuinely necessary, increase memory_limit in php.ini or use ini_set('memory_limit', '256M') at the start of the script.