How Can PHP Efficiently Process Large JSON Files Without Memory Exhaustion?

Processing Large JSON Files in PHP

When handling JSON files that exceed the memory limits, it becomes crucial to devise strategies that minimize memory usage during parsing and processing. This discussion explores efficient methods for handling large JSON files without loading the entire content into memory.

Pull Parsing Approach

Abandoning the typical "slurp and parse" approach, PHP now offers a promising solution: a streaming JSON pull parser called JsonReader. Inspired by XMLReader's API, JsonReader allows users to control the parsing process and retrieve data on demand.

Example 1: Reading Objects as a Whole

use pcrov\JsonReader\JsonReader;

$reader = new JsonReader();
$reader->open("data.json");

$reader->read(); // Outer array
$depth = $reader->depth(); // Track depth to detect when the array ends
$reader->read(); // Move to the first object

while ($reader->next() && $reader->depth() > $depth) {
    print_r($reader->value()); // Process each object
}

$reader->close();

Example 2: Reading Individual Elements

while ($reader->read()) {
    if ($reader->name() !== null) {
        echo "$name: {$reader->value()}\n";
    }
}

Example 3: Reading Duplicates and Specific Properties

$reader = new pcrov\JsonReader\JsonReader();
$reader->json($json);

while ($reader->read("foo")) {
    echo "{$reader->name()}: {$reader->value()}\n";
}

By utilizing JsonReader's pull-parsing capabilities, PHP developers can efficiently process large JSON files, avoiding memory exhaustion and maximizing performance.

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