Memory leak from this code

Stream CSV from Couchbase.php

<?php

$outStream = fopen("php://output", "r+");
fputcsv($outStream, $columnHeadings);

// Create a loop so that we can do paginated couchbase view queries
$finished = false;
$startKeyDocId = null;
$perPage = 5;
while (!$finished) {
    
    // Set up the couchbase view query
    $query = \CouchbaseViewQuery::from('webforms', $cbView);
    $query
        ->order($query::ORDER_ASCENDING)
        ->stale((null === $startKeyDocId ? $query::UPDATE_BEFORE : $query::UPDATE_NONE))
        ->reduce(true)
        ->group(3)
        ->range(
            [$webForm->getType(), $ID, $startKeyDocId],
            [$webForm->getType(), $ID+1, null],
            false
        )
        ->limit($perPage + 1)
    ;

    // Fetch query results
    $result = $bucket->query($query);
    $countRows = count($result['rows']);
    
    // No results means we are done here
    if (0 === $countRows) {
        break;
    }

    // We can try to calculate if this is the last page based on the number of results
    if ($countRows <= $perPage) {
        $finished = true;
    }
    
    // Loop through rows in this paginated result set
    $numLoops = min($countRows, $perPage);
    for ($i = 0; $i < $numLoops; $i++) {
        
        $entryResult = $bucket->get($result['rows'][$i]['key'][2]);
        $doc = $entryResult->value;
        
        // ...
        // here I process the data from $doc into an array $data for csv export
        // ...
        
        fputcsv($outStream, $data);
    }
    
    // Limit is $perPage + 1 so on 0-indexed array a key of $perPage means we fulfilled that limit
    if (array_key_exists($perPage, $result['rows'])) {
        $startKeyDocId = $result['rows'][$perPage]['key'][2];
    }

    flush();
}

fclose($outStream);
exit;

In the real environment, ideally, $perPage would probably be in the region of 1000 or so.