gradual memory increase in long running script

I use Moodle 4.1 Need to run script with php cli which fills csv file with nearly million rows of data. ``` <?php define('CLI_SCRIPT', true); require "config.php"; use core_reportbuilder\table\custom_report_table_view; $table = custom_report_table_view::create(264); $table->setup(); $table->download = 'excel'; $columns = (new table_dataformat_export_format($table, $table->download))->format_data($table->headers); [$sql, $params] = $table->getPaginatedDataSQL(); $filePath = '/var/excelreport/tmp_264_' . date("d-m-Y_H:i:s") . '.csv'; try { $file = fopen($filePath, 'w'); fprintf($file, chr(0xEF).chr(0xBB).chr(0xBF)); echo "File '$filePath' successfully created."; } catch (\Throwable $throwable) { echo $throwable->getMessage(); echo "Failed to create '$filePath'."; } $limit = 10000; $rowCount = $table->getRowsCount(); fputcsv($file, $columns,';'); for ($offset = 0; $offset < $rowCount; $offset += $limit) { $chunk = $DB->get_records_sql($sql. " LIMIT $limit OFFSET $offset", $params); // here $DB is global variable which comes from config.php foreach ($chunk as $row) { $row = array_values($table->format_row($row)); fputcsv($file, $row,';'); } echo "\n offset $offset memory: ". (memory_get_usage() / 1024)."KB\n" ; unset($chunk); gc_collect_cycles(); } $table->close_recordset(); fclose($file); ``` Simply I fetch data chunks with size of 10000 rows from moodle's db and append to file in each iteration with fputcsv. After each iteration I echo memory usage which increases as script runs. [enter image description here](https://i.sstatic.net/UmcGoqrE.png) Did I miss something to free or php somehow increases its memory footprint in long running tasks? AS a solution should I execute each chunk as seperate process with exec?